linear magnetic field sensors - SP

linear magnetic field sensors - SP
SENSOR PRODUCTS
APPLICATIONS
Compassing
Navigation Systems
1- and 2-Axis Magnetic
Sensors
HMC1001 / 1002
HMC1021 / 1022
Attitude Reference
Traffic Detection
Medical Devices
C
onfigured as a 4-element
wheatstone bridge, these
magnetoresistive sensors
convert magnetic fields to
a differential output voltage, capable of sensing
magnetic fields as low as
30 µgauss. These MRs
offer a small, low cost,
high sensitivity and high
reliability solution for low
field magnetic sensing.
Non-Contact Switch
Not actual size
FEATURES AND BENEFITS
Wide Field Range Field range up to ±6 gauss, (earth’s field = 0.5 gauss)
Small Package
• Designed for 1- and 2-axis to work together to provide 3-axis (x, y, z) sensing
• 1-axis part in an 8-pin SIP or an 8-pin SOIC or a ceramic 8-pin DIP package
• 2-axis part in a 16-pin or 20-pin SOIC package
Solid State
These small devices reduce board assembly costs, improve reliability and ruggedness compared to mechanical fluxgates.
On-Chip Coils
Patented on-chip set/reset straps to reduce effects of temperature drift, non-linearity errors and
loss of signal output due to the presence of high magnetic fields
Patented on-chip offset straps for elimination of the effects of hard iron distortion
Cost Effective
The sensors were specifically designed to be affordable for high volume OEM applications.
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LINEAR MAGNETIC FIELD SENSORS
HMC1001/1002 SPECIFICATIONS
Characteristics
Conditions*
Min
Bridge Supply
Vbridge referenced to GND
Bridge Resistance
Bridge current = 10mA
Typ
Max
Unit
5
12
Volts
850
1200
ohm
-55
150
°C
600
Operating Temperature (4)
Storage Temperature (4)
Unbiased
-55
175
°C
Field Range (4)
Full scale (FS), total applied field
-2
+2
gauss
Linearity Error (4)
Best fit straight line
0.1
1
0.5
2
%FS
Hysteresis Error (4)
3 sweeps across ±2 gauss
0.05
0.10
%FS
Repeatability Error (4)
3 sweeps across ±2 gauss
0.05
0.10
%FS
S/R Repeatability (1)
S/R Repeatability (2)
Output variation after alternate S/R pulses
2
10
100
µV
±1 gauss
±2 gauss
Bridge Offset
Offset = (OUT+) – (OUT-), Field=0 gauss
after Set pulse, Vbridge=8V
-60
-15
30
mV
Sensitivity
S/R Current = 3A
2.5
3.2
4.0
mV/V/gauss
Noise Density (4)
Noise at 1 Hz, Vbridge=5V
29
nV/ Hz
Resolution (4)
Bandwidth=10Hz, Vbridge=5V
27
µgauss
Bandwidth (4)
Magnetic signal (lower limit = DC)
5
MHz
OFFSET Strap
Measured from OFFSET+ to OFFSET-
2.5
OFFSET Strap Ω Tempco (4) TA = -40 to 125° C
3.5
0.39
OFFSET Field (4)
Field applied in sensitive direction
46
Set/Reset Strap
Measured from S/R+ to S/R-
Set/Reset Current (2) (3) (4)
2 µs current pulse, 1% duty cycle
Set/Reset Ω Tempco (4)
T A = -40 to 125° C
Disturbing Field (4)
Sensitivity starts to degrade.
Use S/R pulse to restore sensitivity.
Sensitivity Tempco (4)
T A = -40 to 125° C
Bridge Offset Tempco (4)
T A = -40 to 125° C no Set/Reset
Vbridge=5V
with Set/Reset
Resistance Tempco (4)
3.0
%/° C
51
56
mA/gauss
1.5
1.8
ohm
3.2
5
Amp
0.37
Vbridge=8V
Ibridge=5mA
%/° C
3
-0.32
ohm
gauss
-0.3
-0.06
-0.28
%/° C
±0.03
±0.001
%/° C
T A = -40 to 125° C
0.25
%/° C
Cross-Axis Effect (4)
Cross field=1gauss no Set/Reset
(see AN-205)
with Set/Reset
±3
+0.5
%FS
Max. Exposed Field (4)
No perming effect on zero reading
Weight
HMC1001
HMC1002
(1)
(2)
(3)
(4)
(*)
10000
0.14
0.53
gauss
gram
VBridge = 4.3V, IS/R = 3.2A, VOUT = VSET – VRESET
If VBridge = 8.0V, IS/R = 2.0A, lower S/R current leads to greater output variation.
Effective current from power supply is less than 1mA.
Not tested in production, guaranteed by characterization.
Tested at 25° C except otherwise stated.
Units: 1 gauss (g) = 1 Oersted (in air), = 79.58 A/m, 1G = 10E-4 Tesla, 1G = 10E5 gamma.
2
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LINEAR MAGNETIC FIELD SENSORS
HMC1021/1022 SPECIFICATIONS
Characteristic
Conditions**
Min
Typ
Max
Unit
Bridge Supply
Vbridge referenced to GND
5
25
Volts
Bridge Resistance
Bridge current = 5mA
800
1100
1300
Ω
Operating Temperature (1)
HMC1021S, 1021Z, 1022
HMC1021D*
-55
- 55
150
300*
°C
Storage Temperature (1)
Unbiased
-55
175
°C
Field Range (1)
Full scale (FS), — total applied field
-6
+6
gauss
Linearity Error (1)
Best fit straight line ±1 gauss
±3 gauss
±6 gauss
0.05
0.4
1.6
%FS
Hysteresis Error (1)
3 sweeps across ±3 gauss
0.08
%FS
Repeatability Error (1)
3 sweeps across ±3 gauss
0.08
%FS
Bridge Offset
Offset = (OUT+) – (OUT-), Field = 0 gauss
After Set pulse, Vbridge=5V
-10
±2.5
11.25
mV
Sensitivity
S/R Current = 0.5A
0.8
1.0
1.25
mV/V/gauss
Noise Density (1)
Noise at 1Hz, Vbridge=5V
48
nV/√Hz
Resolution (1)
Bandwidth=10Hz, Vbridge=5V
85
µgauss
Bandwidth (1)
Magnetic signal (lower limit = DC)
5
MHz
OFFSET Strap
Measured from OFFSET+ to OFFSET-
OFFSET Strap Ω Tempco (1)
TA = -40 to 125° C
OFFSET Field (1)
Field applied in sensitive direction
4.0
4.6
6.0
mA/gauss
Set/Reset Strap
Measured from S/R+ to S/R-
5.5
7.7
9
Ω
Set/Reset Current
2µs current pulse, 1% duty cycle
0.5
0.5
4.0
Amp
Set/Reset Ω Tempco (1)
TA = -40 to 125° C
Disturbing Field (1)
Sensitivity starts to degrade. Use S/R
pulse to restore sensitivity.
Sensitivity Tempco (1)
TA = -40 to 125° C
Bridge Offset Tempco (1)
TA = -40 to 125° C no Set/Reset
Vbridge=5V
with Set/Reset
Resistance Tempco (1)
Cross-Axis Effect (1)
38
50
60
0.39
%/° C
0.37
Vbridge=5V
Ibridge=5mA
%/° C
20
-0.32
Ω
gauss
-0.3
-0.06
-0.28
%/° C
±0.05
±0.001
%/° C
Vbridge=5V, TA = –40 to 125° C
0.25
%/° C
Cross field=1 gauss
(see AN-205) Happlied=±1 gauss
+0.3
%FS
Max. Exposed Field (1)
No perming effect on zero reading
Set/Reset (1)
S/R current ≥ 0.5 Amps
10000
gauss
30
µV
*Please reference data sheet, HTMC1021D for specifications.
(1) Not tested in production, guaranteed by characterization.
Units: 1 gauss (G) = 1 Oersted (in air), 1G = 79.58 A/m,
1G = 10E-4 Tesla, 1G = 10E5 gamma
**Tested at 25° C except otherwise stated.
3
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LINEAR MAGNETIC FIELD SENSORS
KEY PERFORMANCE DATA
Sensor output vs magnetic field
Output is repeatable in field range ±20 Oe
Sensor output vs magnetic field
after being set or reset
15
60
1021/1022
1021/1022
10
40
Voltage Output (mV)
Output Voltage (mV)
Vb=5V
5
0
Reset
-5
Set
-10
Vb=5V
20
0
-20
2 sweeps
2 sweeps
-40
-15
-60
-20
-2
-1
0
1
-20
2
-15
-10
-5
0
5
Sensor noise vs frequency
15
20
Sensitivity vs temperature
Constant voltage power supply
1.3
1000
1021/1022
1021/1022
1.2
Vb=5V
Vb=5V
Sensitivity (mV/V/Oe)
Noise Density (nV/rt Hz)
10
Field (Oe)
Field (Oe)
100
10
1.1
1
0.9
0.8
0.7
0.6
1
0.1
1
10
100
-50
1000
-25
0
Frequency (Hz)
25
50
75
100
125
Temperature (C)
Effects of set/reset pulse variation
2µ sec pulse duration, S/R voltage >4V is recommended
Bridge resistance vs temperature
1400
1
Vb=5V
1021/1022
All types
0.8
Vb=5V
Nonrepeatability
Resistance (ohm)
1300
1200
1100
Null Voltage (mV) (Set)
Sensitivity (mV/V/Oe) (Set)
0.4
0.2
900
0
-25
0
25
50
75
100
Sensitivity (mV/V/Oe) (Reset)
noset/reset
set/resetinint
no
region
this
region
1000
-50
Null Voltage (mV) (Reset)
0.6
0
125
Temperature (C)
1
2
3
4
5
Set/Reset Voltage (V)
4
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LINEAR MAGNETIC FIELD SENSORS
PACKAGE / PINOUT SPECIFICATIONS
HMC1001—One Axis MR Microcircuit
HMC1002—Two-Axis MR Microcircuit
GND1 (A) 1
20 S/R- (A)
OUT+ (A) 2
Die A
OFFSET- (A) 3
Vbridge (A) 4
18 GND PLN
17 OFFSET (+A)
OUT- (A) 5
16 S/R+ (A)
GND2 (A) 6
Die B
S/R- (B) 7
15 OFFSET+ (B)
14 S/R+ (B)
GND1 (B) 8
13 GND2 (B)
Out+ (B) 9
12 OUT- (B)
OFFSET- (B) 10
11 Vbridge (B)
HMC1022—Two-Axis MR Circuit
OFFSET- (A)
OUT+ (A)
VBRIDGE (A)
OUT- (A)
OUT- (B)
VBRIDGE (B)
GND (A)
S/R+ (B)
1
2
3
4
5
6
7
8
•Die A
16
15
14
13
12
11
10
9
Die B
1
2
3
4
Die
8
7
6
5
Die
HMC1021S—One-Axis MR Circuit
OFFSET+ (A)
S/R- (A)
S/R+ (A)
GND (B)
OUT+ (B)
OFFSET- (B)
OFFSET+ (B)
S/R- (B)
OUT+
VBRIDGE
GND
OUT-
1
2
3
4
• Die
8
7
6
5
OFFSETOFFSET+
S/RS/R+
HMC1021S
HMC1021D—One-Axis MR Circuit
OUT+
VBRIDGE
GND
OUT-
•
S/R+ 1
OFFSET+ 2
S/R- 3
GND 4
Out+ 5
OFFSET- 6
Vbridge 7
Out- 8
19 NC
HMC1021Z—One-Axis MR Circuit
OUTVBRIDGE
S/R+
GND
S/ROFFSET+
OFFSETOUT+
OFFSETOFFSET+
S/RS/R+
1
2
3
4
5
6
7
8
•
Die
Arrow indicates direction of applied field that generates a
positive output voltage after a SET pulse.
5
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LINEAR MAGNETIC FIELD SENSORS
BASIC DEVICE OPERATION
The OFFSET strap allows for several modes of operation
when a dc current is driven through it.
Honeywell magnetoresistive sensors are simple resistive
bridge devices (Figure 1) that only require a supply voltage
to measure magnetic fields. When a voltage from 0 to 10
volts is connected to Vbridge, the sensor begins measuring
any ambient, or applied, magnetic field in the sensitive axis.
In addition to the bridge circuit, the sensor has two on-chip
magnetically coupled straps—the OFFSET strap and the
Set/Reset strap. These straps are patented by Honeywell
and eliminate the need for external coils around the devices.
Vbridge
(7)
R
OFFSET +
(2)
R
3.5 Ω max.
• An unwanted magnetic field can be subtracted out
• The bridge offset can be set to zero
• The bridge output can drive the OFFSET strap to cancel
out the field being measured in a closed loop configuration
• The bridge gain can be auto-calibrated in the system on
command.
The Set/Reset (S/R) strap can be pulsed with a high current to:
OFFSET (6)
• Force the sensor to operate in the high sensitivity mode
• Flip the polarity of the output response curve
• Be cycled during normal operation to improve linearity
and reduce cross-axis effects and temperature effects.
Ioffset
R=600-1200 Ω
OUT+
(5)
OUT(8)
R
R
2.0 Ω max.
S/R +
(1)
S/R (3)
Iset, -Ireset
GND
(4)
The output response curves shown in Figure 2 illustrate the
effects of the S/R pulse. When a SET current pulse (Iset) is
driven into the SR+ pin, the output response follow the curve
with the positive slope. When a RESET current pulse
(Ireset) is driven into the SR- pin, the output response follow
the curve with the negative slope. These curves are mirror
images about the origin except for two offset effects.
Figure 1—On-Chip components (HMC1001)
Magnetoresistive sensors are made of a nickel-iron
(Permalloy) thin film deposited on a silicon wafer and
patterned as a resistive strip. In the presence of an applied
magnetic field, a change in the bridge resistance causes a
corresponding change in voltage output.
In the vertical direction, the bridge offset shown in Figure 2,
is around -25mV. This is due to the resistor mismatch during
the manufacture process. This offset can be trimmed to zero
by one of several techniques. The most straight forward
technique is to add a shunt (parallel) resistor across one leg
of the bridge to force both outputs to the same voltage. This
must be done in a zero magnetic field environment, usually
in a zero gauss chamber.
An external magnetic field applied normal to the side of the
film causes the magnetization vector to rotate and change
angle. This in turn will cause the resistance value to vary (∆R/
R) and produce a voltage output change in the Wheatstone
bridge. This change in the Permalloy resistance is termed the
magnetoresistive effect and is directly related to the angle of
the current flow and the magnetization vector.
The offset of Figure 2 in the horizontal direction is referred to
here as the external offset. This may be due to a nearby ferrous
object or an unwanted magnetic field that is interfering with the
applied field being measured. A dc current in the OFFSET
strap can adjust this offset to zero. Other methods such as
shielding the unwanted field can also be used to zero the
external offset. The output response curves due to the SET
and RESET pulses are reflected about these two offsets.
During manufacture, the easy axis (preferred direction of
magnetic field) is set to one direction along the length of the
film. This allows the maximum change in resistance for an
applied field within the permalloy film. However, the influence
of a strong magnetic field (more than 10 gauss) along the
easy axis could upset, or flip, the polarity of film
magnetization, thus changing the sensor characteristics.
Following such an upset field, a strong restoring magnetic
field must be applied momentarily to restore, or set, the
sensor characteristics. This effect will be referred to as
applying a set pulse or reset pulse. Polarity of the bridge
output signal depends upon the direction of this internal film
magnetization and is symmetric about the zero field output.
40
Vcc=8V
Output Voltage (mV)
20
(1001/1002)
response
after Iset
response
after Ireset
0
bridge
offset
-20
-40
external
offset
-60
1.50
1.25
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
-1.00
-1.25
-1.50
-80
Applied Field (Gauss)
Figure 2—Output Voltage vs. Applied Magnetic Field
6
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LINEAR MAGNETIC FIELD SENSORS
NOISE CHARACTERISTICS
The noise density curve for a typical MR sensor is shown
in Figure 3. The 1/f slope has a corner frequency near 10
Hz and flattens out to 3.8 nV/√Hz. This is approximately
equivalent to the Johnson noise (or white noise) for an
850Ω resistor—the typical bridge resistance. To relate the
noise density voltage in Figure 3 to the magnetic fields, use
the following expressions:
then it can be compensated for by applying an equal and
opposite field using the OFFSET strap. Another use for the
OFFSET strap would be to drive a current through the strap
that will exactly cancel out the field being measured. This is
called a closed loop configuration where the current feedback
signal is a direct measure of the applied field.
The field offset strap (OFFSET+ and OFFSET-) will generate
a magnetic field in the same direction as the applied field
being measured. This strap provides a 1 Oersted (Oe) field
per 50 mA of current through it in HMC1001/2 and 1 Oe/5mA
in HMC1021/2. (Note: 1 gauss=1 Oersted in air). For
example, if 25 mA were driven from the OFFSET+ pin to the
OFFSET- pin in HMC1001/2, a field of 0.5 gauss would be
added to any ambient field being measured. Also, a current
of -25 mA would subtract 0.5 gauss from the ambient field.
The OFFSET strap looks like as a nominal resistance
between the OFFSET+ and OFFSET- pins.
For Vsupply=5V and Sensitivity=3.2mV/V/gauss,
Bridge output response = 16 mV/gauss
or
16 nV/µgauss
The noise density at 1Hz ≈ 30nV/√Hz
and corresponds to
1.8 µgauss/√Hz
For the noise components, use the following expressions:
30 * √(ln(10/.1)) nV
64 nV (rms)
4 µgauss (rms)
27 µgauss (p-p)
1/f noise(0.1-10Hz) =
The OFFSET strap can be used as a feedback element in
a closed loop circuit. Using the OFFSET strap in a current
feedback loop can produce desirable results for measuring
magnetic fields. To do this, connect the output of the bridge
amplifier to a current source that drives the OFFSET strap.
Using high gain and negative feedback in the loop, this will
drive the MR bridge output to zero, (OUT+) = (OUT-). This
method gives extremely good linearity and temperature
characteristics. The idea here is to always operate the MR
bridge in the balanced resistance mode. That is, no matter
what magnetic field is being measured, the current through
the OFFSET strap will cancel it out. The bridge always
“sees” a zero field condition. The resultant current used to
cancel the applied field is a direct measure of that field
strength and can be translated into the field value.
3.8 * √BW nV
120 nV (rms)
50 µgauss (p-p)
white noise (BW=1KHz) =
(1001/1002)
100
Noise
Density
(nV/ √ Hz)
1000
The OFFSET strap can also be used to auto-calibrate the
MR bridge while in the application during normal operation.
This is useful for occasionally checking the bridge gain for
that axis or to make adjustments over a large temperature
swing. This can be done during power-up or anytime during
normal operation. The concept is simple; take two point
along a line and determine the slope of that line—the gain.
When the bridge is measuring a steady applied magnetic
field the output will remain constant. Record the reading for
the steady field and call it H1. Now apply a known current
through the OFFSET strap and record that reading as H2.
The current through the OFFSET strap will cause a change
in the field the MR sensor measures—call that delta applied
field (∆Ha). The MR sensor gain is then computed as:
10
1
0.1
1
10
Frequency
100
1000
(Hz)
Figure 3—Typical Noise Density Curve
WHAT IS OFFSET STRAP?
Any ambient magnetic field can be canceled by driving a
defined current through the OFFSET strap. This is useful
for eliminating the effects of stray hard iron distortion of the
earth’s magnetic field. For example, reducing the effects of
a car body on the earth’s magnetic field in an automotive
compass application. If the MR sensor has a fixed position
within the automobile, the effect of the car on the earth’s
magnetic field can be approximated as a shift, or offset, in
this field. If this shift in the earth's field can be determined,
MRgain = (H2-H1) / ∆Ha
There are many other uses for the OFFSET strap than those
described here. The key point is that ambient field and the
OFFSET field simply add to one another and are measured
by the MR sensor as a single field.
7
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LINEAR MAGNETIC FIELD SENSORS
WHAT IS SET/RESET STRAP?
Most low field magnetic sensors will be affected by large
magnetic disturbing fields (>4 - 20 gauss) that may lead to
output signal degradation. In order to reduce this effect, and
maximize the signal output, a magnetic switching technique
can be applied to the MR bridge that eliminates the effect
of past magnetic history. The purpose of the Set/Reset
(S/R) strap is to restore the MR sensor to its high sensitivity
state for measuring magnetic fields. This is done by pulsing
a large current through the S/R strap. The Set/Reset (S/R)
strap looks like a resistance between the SR+ and SR- pins.
This strap differs from the OFFSET strap in that it is
magnetically coupled to the MR sensor in the cross-axis, or
insensitive, direction. Once the sensor is set (or reset), low
noise and high sensitivity field measurement can occur. In
the discussion that follows, the term “set” refers to either a
set or reset current.
longer, to conserve power. The only requirement is that
each pulse only drive in one direction. That is, if a +3.5 amp
pulse is used to “set” the sensor, the pulse decay should not
drop below zero current. Any undershoot of the current
pulse will tend to “un-set” the sensor and the sensitivity will
not be optimum.
When MR sensors exposed to a magnetic disturbing field,
the sensor elements are broken up into ramdonly oriented
magnetic domains (Figure 4A) that leads to sensitivity
degrading. A current pulse (set) with a peak current above
minimum current in spec through the Set/Reset strap will
generate a strong magnetic field that realigns the magnetic
domains in one direction (Figure 4B). This will ensure a high
sensitivity and repeatable reading. A negative pulse (Reset)
will rotate the magnetic domain orientation in the opposite
direction (Figure 4C), and change the polarity of the sensor
outputs. The state of these magnetic domains can retain for
years as long as there is no magnetic disturbing field
present.
• Another pulse of equal and opposite current should be
driven through the S/R pins to perform a "RESET" condition. The bridge output can then be measured and stored
as Vout(reset).
Using the S/R strap, many effects can be eliminated or
reduced that include: temperature drift, non-linearity errors,
cross-axis effects, and loss of signal output due to the
presence of a high magnetic fields. This can be accomplished by the following process:
• A current pulse, Iset, can be driven from the S/R+ to the
S/R- pins to perform a “SET” condition. The bridge output
can then be measured and stored as Vout(set).
• The bridge output, Vout, can be expressed as: Vout =
[Vout(set) - Vout(reset)]/2. This technique cancels out
offset and temperature effects introduced by the electronics as well as the bridge temperature drift.
There are many ways to design the set/reset pulsing circuit,
though, budgets and ultimate field resolution will determine
which approach will be best for a given application. A simple
set/reset circuit is shown in Figure 5.
Permalloy (NiFe) Resistor
6-9V
Random
Domain
Orientations
Easy Axis
Magnetization
3
IRF7105
25K
0.2µF
Fig.4A
S/R+
After a
Set Pulse
S/R-
Fig.4B
4
RESET
SET
RESET
Signal should be in
RESET state when idle
0.1µF
5,6
7,8
2
1
Signal input
5V
Manual Switch
Figure 5—Single-Axis Set/Reset Pulse Circuit (1001)
Magnetization
The magnitude of the set/reset current pulse depends on
the magnetic noise sensitivity of the system. If the minimum
detectable field for a given application is roughly 500
µgauss in HMC1001/2, then a 3 amp pulse (min) is adequate.
If the minimum detectable field is less than 100 µgauss,
then a 4 amp pulse (min) is required. The circuit that
generates the S/R pulse should be located close to the MR
sensor and have good power and ground connections.
After a
Reset Pulse
Fig.4C
Figure 4—
The on-chip S/R should be pulsed with a current to realign,
or “flip”, the magnetic domains in the sensor. This pulse can
be as short as two microsecond and on average consumes
less than 1 mA dc when pulsing continuously. The duty
cycle can be selected for a 2 µsec pulse every 50 msec, or
The set/reset straps on the Honeywell magnetic sensors
are labeled S/R+ and S/R-. There is no polarity implied
since this is simply a metal strap resistance.
8
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LINEAR MAGNETIC FIELD SENSORS
SET and RESET signals are generated from a
microprocessor and control the P and N channel HEXFET
drivers (IRF7105). The purpose of creating the TRS and the
TSR delays are to make sure that one HEXFET is off before
the other one turns on. Basically, a break-before-make
switching pattern. The current pulse is drawn from the 4.7
µF capacitor. If the 5V to 20V converter is used as shown in
Figure 7, then the resultant noise and droop on the 16-20V
supply is not an issue. But if the 16-20V supply is used
elsewhere in the system, then a series dropping resistor
(≈500Ω) should be placed between the 4.7µF capacitor and
the supply.
Single Clock Circuitry—Some form of clock is needed to
trigger the set and reset pulses (Figure 6) to create the
switching signal. The circuit shown in Figure 8 can be used
to create a strong (>4Amp) pulse. The diodes, resistors,
capacitors and inverters basically create the TRS and the
TSR delays. Now a single signal (Clock) can trigger a set or
reset pulse. The minimum timing between the rising and
falling edges of Clock are determined by the 25KΩ and 1nF
time constant. That is, the minimum high and low time for
Clock is ≈25 µs.
Micro Processor—The circuit in Figure 9 generates a strong
set/reset pulse (>4 Amp) under microprocessor control. The
MAX662A
2
C1+
C2-
C1-
C2+
3
0.22µF*
5V
0.22µF*
1
Clock
8
16V
7
set
TPW ≈ 2 µsec
5V
5
S/R
4
1µF
SHDN
GND
Vout
20V
6
1N5818
Vcc
2µF
-16V
12V
1µF
reset
1µF
* Use tantalum capacitors
Figure 6—Single Clock Set/Reset Timing
Figure 7—5V to 20V Converter
+16 to 20V
4.7µF (3)
5V
9
8
25K
74HC04
25K
3
25K
3
4
IRF7106 (1)
Clock
14
4
7
1N4001
1nF
25K
1
2
5
6
0.1µF
10K
S/R strap @ 4.5Ω typ.
3A peak (min.)
HMC2003 *
17
0.22µF (2)
1
5,6
7,8
2N3904
2
S/R
1
1nF
(1) HEXFETs with ≈0.2Ω Ron
(2) 0.22µF Tantalum or a
0.68 µF Ceramic CK06
(3) Tantalum, low R
Figure 8—Single Clock Set/Reset Pulse Circuit (1001/1002)
+16 to 20V
5V
4.7µF (1)
SET
25K
25K
TRS
3
TSR
IRF7106 (2)
RESET
4
16V
set
10K
0.1µF
SET
S/R
TRS ≥ 5 µsec
TSR ≥ 5 µsec
TPW ≈ 2 µsec
-16V
reset
HMC2003 *
17
0.22µF
1
5,6
7,8
2N3904
TPW
S/R strap @ 4.5Ω typ.
3A peak (min.)
2
RESET
S/R
1
(1) Tantalum, low R
(2) HEXFETs with ≈0.2Ω Ron
•HMC2003 contains one HMC1001 and one HMC1002; together they make the 3-axis sensor.
Three S/R straps are in serial, the total resistance is ~4.5Ω.
Figure 9—Set/Reset Circuit With Microprocessor Control (1001/1002)
9
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LINEAR MAGNETIC FIELD SENSORS
Low Field Measurements—When measuring 100 µgauss
resolution or less, the permalloy film must be completely
set, or reset, to insure low noise and repeatable
measurements. A current pulse of 4 amps, or more, for just
a couple microseconds will ensure this. The circuits in
Figures 8 and 9 are recommended for applications of
HMC1001/2 that require low noise and high sensitivity
magnetic readings.
For any magnetic sensor application, if temperature drift is
not an issue, then the reset pulse need only be occasionally
applied. This will save power and enable the use of digital
filtering techniques as shown in Figure 12. Circumstances
for a reset pulse would be 1) power on or, 2) field over/
under range condition. Any other time the sensor should
perform normally.
200
1µF
1µF(1)
(1)
+5V
Low Cost—For minimum field measurements above 500
µgauss, a less elaborate pulsing circuit can be used. In both
Figures 10 and 11, the pulse signal is switched using lower
cost Darlington transistors and fewer components. This circuit
may have a more limited temperature range depending on the
quality of transistors selected. If accuracy is not an issue and
cost is, then the reset only circuit in Figure 11 will work.
10K
0.1µF
0.1µF
14
8
9,15
0.1µF
0.1µF
Clock
+16 to 20V
4.7µF (1)
FMMT617
10K
10K
HMC1022
FMMT717
(1) Tantalum, low R
S/R strap @ 4.5Ω typ.
3A peak (min.)
0.022µF
ZTX705
HMC2003*
17
0.22µF
Figure 12—5V Circuit for SET/RESET (1021/1022)
1
The circuit in Figure 13 generates a strong set/reset pulse
under a microprocessor clock driven control. A free running
555 timer can also be used to clock the circuit. The SET
current pulse is drawn from the 1 µF capacitor and a 200
ohm dropping resistor should be placed in series with the
supply to reduce noise.
0.022µF
Clock
ZTX605
S/R
10K
(1) Tantalum, low R
Figure 10—Single Clock Set/Reset Circuit (1001/1002)
S/R strap @ 4.5Ω typ.
3A peak (min.)
+16 to 20V
100K
HMC2003 *
0.22µF
17
1
0.022µF
Clock
ZTX605
S/R
10K
5V
Clock
S/R
TPW ≈ 2 µsec
-16V
reset
*The HMC2003 has 3-axis S/R straps in series.
These are the HMC1001 and HMC1002 sensors.
Figure 11—Single Clock Reset Only Circuit (1001/1002)
10
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LINEAR MAGNETIC FIELD SENSORS
200
1µF (1)
+5 to 6V
5V
3
Clock
HMC1022
4
4 to14V
IRF7105 (2)
DI9952 (2)
set
TPW ~ 2 µsec
14
8
9,15
0.1µF
S/R
reset
set
rst
5,6
7,8
2
Clock
-4 to -14V
S/R
1
set
(1) Tantalum, low R
(2) Rds ~0.2 ohm
Figure 13—Set/Reset Pulse With Clock Control (1021/1022)
Low Power—For low power application, down to 3.3 volt
supply, the circuit shown in Figure 15 can be used. These
low threshold FETs provide low on-resistance (0.3Ω) at
VGS=2.7V. The set/reset pulsing does not need to be
continuous. To save power, the SET pulse can be initially
applied followed by a single RESET pulse. The offset (OS)
can be calculated as:
SET Pulse
Read Vset
RESET Pulse
Read Vrst
OS = (Vset + Vrst)/2
OS = (Vset+Vrst)/2
This offset term will contain the DC offset of both the sensor
bridge and interface electronics, as well as the temperature
drift of the bridge and interface electronics. Store this value
and subtract it from all future bridge output readings. Once
the bridge is RESET, it will remain in that state for years—
or until a disturbing field (>20 gauss) is applied. A timer can
be set, say every 10 minutes, to periodically update the
offset term. A flow chart is shown in Figure 14 along with a
timing diagram in Figure 15 to illustrate this process.
Ta
Tb T a
Vout = Vrst - OS
Timer
expired?
n
Read Vrst
Figure 14—Low Power Set/Rst Flowchart
Tc
200
Reset
+3.3 to
6.5V
Set
1,3
Td
Td
Set
read
Vrst
read
Vset
Vout
set
1µF (1)
+
HMC1022
2,4
14
5,6,7,8
Vp
9,15
0.1µF
NDS8926
(1) Tantalum, low R
(2) Rds ~0.2 ohm
5,6,7,8
S/R
Reset
TPW
Ta > 5 µsec
Tb > 1 µsec
Tc > 20 µsec, 50 msec(max)
Td > 20 µsec
8
NDS9933
2,4
S/R
y
-Vp
1,3
reset
TPW ~ 2 µsec
Vp > 3 V
Figure 15—Single Clock Set/Reset Pulse Circuit (1021/1022)
11
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LINEAR MAGNETIC FIELD SENSORS
Simple Circuit Application
strong (200 gauss) and have one of its magnetic poles
point along the sensitive direction of the sensor. This
circuit can be used to detect a door open/closed status or
the presence or absence of an item. Figures 17, 18, 19,
20 and 21 show other circuit examples.
The circuit in Figure 16 shows a simple application of a
magnetic sensor. This circuit acts as a proximity sensor
and will turn on the LED when a magnet is brought within
0.25 to 0.5 inch of the sensor. The amplifier acts as a
simple comparator and switches low when the HMC1001
bridge output exceeds 30mV. The magnet must be
+5V
100
7
1
8
V+
3
5
V-
2
400
8
+
AMP04
-
R1*
6
LED
5
4
650
8
2
5
3
8
+
R2*
3
7
Ain+
8
AMP04
5
Ain-
V+
25K
Vref
9
10
LM440
2.5V
1
Calibrate:
1. Trim R1 for (+V) - (-V) < 30mV
2. Apply signal < 30mV, LED should be off.
3. Apply signal > 30mV, LED should be on.
Vout
6
1.6Ω
Gain=1000, BW=10Hz
* R1 is used to trim switchpoint
# provides 10Hz rolloff
CS5509
16 bit A/D
1.5nF#
1
R1*
4
Vout
4
V+
7
0.15µF#
12
V+
CONV
SCLK
Ref+
SDATA
NDRDY
XIN
RefGnd
CAL
NCS
6,11,13
2
+5V
14
15
16
4
3
Serial Bus
Interface
HMC1001
7
magnet
movement
Magnetic
Sensor
+5V
+5V
HMC1001
Magnetic
Sensor
1
* R1 or R2 used to trim offest
# provides 1KHz rolloff
S/R
Pulse
Figure 17—One-Axis Sensor With Digital Interface
Figure 16—Magnetic Proximity Switch
+6-15V
Magnetic
Sensor
BS250
100K
LMC7101
+ -
22.1K
R3**
10
3
R1*
CS5509
16 bit A/D
8
2
3
5
8
+
R2*
4
5 mA
1
Vref
9
Ref+
12
V+
CONV
SCLK
SDATA
NDRDY
Ain-
10
LM440
2.5V
S/R
Pulse
Ain+
V+
25K
1
7
8
AMP04
5
1.6Ω
3
Vout
6
RefGnd
XIN
CAL
NCS
6,11,13
+5V
2
14
15
Serial Bus
Interface
4
650
1.5nF#
HMC1001
1
Vref
V+
7
0.01
16
4
3
1
* R1 or R2 used to trim offest
**R3 = 451Ω for 1 axis, 921Ω for 2 axis, or 1411Ω for 3 axis
# provides 1KHz rolloff
Figure 18—One-Axis Sensor With Constant Bridge Current and Digital Interface
+5V
+5V
10K
4.7uF
tantalum
SW1
1M
OUT-1
V BRIDGE2
S/R+3
GND4
S/R-5
OFFSET+6
OFFSET-7
OUT+8
V+
200
Sensitive
Direction
-
Vout
AMP623
+
+5V
2.5V
HMC1021S
Z
25K
LM404-2.5
Gnd
(1) Momentarily close switch SW1. This creates a SET pulse. (2) Measure bridge output (OUT+) - (OUT-) NOTE: Bridge
output signal will be 5mV/gauss (3) Measure Vout after AD623 amplifier (G~500) NOTE: Vout signal will be 2.5V/gauss
Figure 19—One-Axis Low Cost Sensor
12
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LINEAR MAGNETIC FIELD SENSORS
Magnetic
Magnetic
SensorS
Sensors
V+
4
+5V
5
X
650
2
3
2
TLC2543
12 bit A/D
8
+
6
1
AMP04
2
V+
11
+5V
R3*
Y
3
12
13
1.5nF#
RefGnd
10
20
+5V
18
17
16
15
19
8
+
R4*
DOUT
NCS
EOC
Ref+
1
2
8,13
14
650
9
AIN1
5
Vref
HMC1002
V+
CLK
DIN
AIN0
Serial Bus
Interface
R2*
1,6
1.5nF#
1
R1*
6
+5V
AMP04
5
25K
Vref
20
14
LM440
2.5V
1.6
1.6
7,18
16
MAX662A
3
* R1-R4 used to trim offest
# provides 1KHz rolloff
+
4
12V
4.7µF
tantalum
C2+
C1Vcc
SHDN
Vout
GND
4.7µF
25K
IRF7105
6
C1+
+
1K
3
0.2µF
0.22µF
C2-
4
2
+
1
0.22µF
5
+5V
8
4.7µF
7
0.1µF
0.1µF
5,6
7,8
SR
2
Rst
Signal input
5V
Manual Switch
1
Set
Rst
Signal should be in Rst
state when idle
Figure 20—Two-Axis Sensor With Set/Reset Circuit and Digital Interface
+5V
-
10 0 K
+
Vref
Magnetic
Magnetic
Sensors
LM324a
10 0 K
0 .1 u F
Sensor
Vb
-
+
+
LM324b
Vref
Sel 1
Sel 2
Vb
-
+
+
LM324c
AB
Vref
0X
1X
0.1µF
0.1 F
Vref
S/R straps
+
X
2X
3X
0.1µF
0.1 F
4052
Output
Output
Vr ef
Vref
Vb
-
S/R Control
+
+
LM324d
HMC1001
S/R strap
Vref
0.1µF
0.1 F
200
+5V
1µF
1
F
S/R
NDC7001 or
equiv.
Figure 21—Three-Axis Low Cost Magnetic Sensor
13
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LINEAR MAGNETIC FIELD SENSORS
PACKAGE OUTLINES
HMC1002—Package Outline
A1
D
20
11
E
1
H
10
h
Millimeters
Inches
Symbol
A
A1
B
D
E
e
H
h
Max
Min
2.642
2.489
0.279
0.127
0.483
0.457
12.675 12.929
7.417
7.264
1.270 ref
1.270 10.566
ref
0.381
Max
Min
.104
.098
.011
.005
.019
.014
.509
.499
.292
.286
.050 refref
.416
.396
.030
.015
Symbol
A
A1
B
D
E
e
H
h
Min
Max
1.371
1.728
0.101
0.249
0.355
0.483
9.829 11.253
3.810
3.988
1.270 ref
5.314
5.014
6.850
7.300
0.381
0.762
A
e
B
HMC1001—8-Pin SIP and
HMC1021Z—8-Pin SIP
Millimeters
D
H E
1
h × 45°
8
A
e
B
Inches
Min
Max
.054
.068
.004
.010
.014
.019
.387
.443
.150
.157
.050 ref
.197
0.270 .209
0.287
.030
.015
A1
HMC1021D—8-Pin Ceramic DIP
A1
D
8
7
6
1
2
3
Symbol
A
A1
b
D
E
E1
e
Q
L
E1
E
Q
Millimeters
5
4
A
L
e
b
Min
Max
2.718 ref
0.229 0.305
0.406 0.508
10.287
—
7.569
7.163
7.874
7.366
2.54 ref
0.381 1.524
4.445
3.175
Inches
Max
Min
0.107 ref
0.012
0.009
0.020
0.016
0.405
—
0.298
0.282
0.310
0.290
0.100 ref
0.060
0.015
0.175
0.125
HMC1021S—8-Pin SOIC
D
A1
A
H
E
1
•
e
B
h x 45°
Millimeters
Inches
Symbol
A
A1
B
D
E
e
H
h
Min
Max
1.371
1.728
0.101
0.249
0.355
0.483
4.800
4.979
3.810
3.988
1.270 ref
5.816
6.198
0.381
0.762
Min
Max
.068
.054
.004
.010
.019
.014
.196
.189
.150
.157
.050 ref
.229
.244
.030
.015
Symbol
A
A1
B
D
E
e
H
h
Millimeters
Max
Min
1.728
1.371
0.249
0.101
0.483
0.355
11.253
9.829
3.988
3.810
1.270 ref
6.198
5.816
0.762
0.381
Inches
Min
Max
.054
.068
.004
.010
.014
.019
.387
.443
.150
.157
.050 ref
.229
.244
.015
.030
HMC1022—16-Pin SOIC
D
H
E
A1
16
9
1
8
•
e
B
A
h x 45°
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LINEAR MAGNETIC FIELD SENSORS
DESIGN / PACKAGE OPTIONS
Honeywell offers a range of magnetic microcircuit products.
Two different sensor designs and five package
configurations are available:
• HMC1001/1002 series offers a higher sensitivity and
lower field resolution.
Two-axis parts contain two sensors for the x- and y- field
measurements. Single-axis variations include a SIP package
for mounting through the circuit board to create a 3-axis
solution, a SOIC for direct surface mount, and a ceramic DIP
for high performance military and high temperature
applications.
• HMC1021/1022 series offers a wider field range, lower
set/reset current and has a lower cost for higher volume
applications.
HMC1001/02
HMC1021/22
Units
Sensitivity
3.1
1.0
mV/V/G
Resolution
27
85
µgauss
Range
±2
±6
gauss
Set/Rst Current
3.0
0.5
Amps
Cost
Lower in high volume
ORDERING INFORMATION
Part Number
Axis Number
Sensitivity
Package Style
HMC1001
Single
3mV/V/G
8-Pin SIP
HMC1002
Two
3mV/V/G
20-Pin SOIC
HMC1021D
Single
1mV/V/G
8-Pin Ceramic DIP
HMC1021Z
Single
1mV/V/G
8-Pin SIP
HMC1021S
Single
1mV/V/G
8-Pin SOIC
Two
1mV/V/G
16-Pin SOIC
HMC1022
Solid State Electronics Center • 12001 State Highway 55, Plymouth, MN 55441 • (800) 323-8295 • www.magneticsensors.com
Additional Product Details:
Customer Service Representative
(612) 954-2888 fax: (612) 954-2257
E-Mail: [email protected]
Honeywell reserves the right to make changes to any products or technology herein to improve reliability, function or design. Honeywell does not assume any liability
arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
900248 Rev. B
15
4-00
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HMC1023
SENSOR PRODUCTS
3-AXIS MAGNETIC SENSOR
Features
x
x
x
x
x
x
Ball Grid Array (BGA) Surface-Mount Package
Three Orthogonal Magneto-Resistive Sensors
Wide Field Range of ± 6 Gauss
1.0 mV/V/gauss Sensitivity
Minimum Detectable Field to 85Pgauss
Patented On-Chip Set/Reset and Offset Straps
Product Description
The Honeywell HMC1023 is a high performance threeaxis magneto-resistive sensor design in a single
package. The advantages of the HMC1023 include
orthogonal three-axis sensing, small size and a 16contact BGA surface mount package.
Each of the magneto-resistive sensors are configured
as 4-element Wheatstone bridges to convert magnetic
fields to differential output voltages. Capable of sensing
fields down to 85 micro-gauss, these sensors offer a
compact, high sensitivity and highly reliable solution for
low field magnetic sensing.
APPLICATIONS
x Compassing
HMC1023 Circuit Diagram
x Navigation Systems
x Attitude Reference
x Traffic Detection
x Medical Devices
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HMC1023
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions*
Min
Typ
Max
Units
Vbridge referenced to GND
1.8
5.0
12
Volts
Resistance
Bridge current = 5mA, VCC to GND
250
350
450
ohms
Operating
Ambient
-40
125
°C
Ambient, unbiased
-55
125
°C
100
%
+6
gauss
Bridge Elements
Supply
Temperature
Storage
Temperature
Humidity
Field Range
Tested at 121°C
Full scale (FS) – total applied field
Linearity Error
-6
Best fit straight line
± 1 gauss
0.05
± 3 gauss
0.4
± 6 gauss
1.6
Hysteresis Error
3 sweeps across ±3 gauss
0.08
%FS
Repeatability Error
3 sweeps across ±3 gauss
0.08
%FS
Bridge Offset
Offset = (OUT+) – (OUT-)
%FS
-10
±2.5
+10
mV
0.8
1.0
1.2
mV/V/gauss
Field = 0 gauss after Set pulse, VCC = 5V
Sensitivity
Set/Reset Current = 2.0A
Noise Density
@ 1kHz, VCC=5V
48
nV/sqrt Hz
Resolution
50Hz Bandwidth, VCC=5V
85
Pgauss
Bandwidth
Magnetic signal (lower limit = DC)
5
MHz
Disturbing Field
Sensitivity starts to degrade.
20
gauss
Use S/R pulse to restore sensitivity.
Sensitivity
TA= -40 to 125°C, VCC=5V
Tempco
TA= -40 to 125°C, ICC=5mA
-600
TA= -40 to 125°C, No Set/Reset
±500
TA= -40 to 125°C, With Set/Reset
±10
Bridge Offset
Tempco
Bridge Ohmic
VCC=5V, TA= -40 to 125°C
-2800
2100
-3000
2500
-3200
ppm/°C
ppm/°C
2900
ppm/°C
Tempco
Cross-Axis Effect
Max. Exposed
Cross field = 1 gauss, Happlied = ±1 gauss
+0.3
No perming effect on zero reading
%FS
200
gauss
Field
Sensitivity Ratio of
TA= -40 to 125°C
100±5
%
X,Y,Z Sensors
X,Y, Z sensor
Sensitive direction in X, Y and Z sensors
1.0
degree
Orthogonality
* Tested at 25°C except stated otherwise.
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HMC1023
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions*
Min
Typ
Max
Units
Measured from S/R+ to S/R-
2.0
3.0
4.0
ohms
0.1% duty cycle, or less,
1.5
2.0
4.0
Amp
TA= -40 to 125°C
3300
3700
4100
ppm/°C
Measured from OFFSET+ to OFFSET-
40
50
60
ohms
DC Current
4.0
4.6
6.0
mA/gauss
3500
3900
4300
ppm/°C
Set/Reset Strap
Resistance
Current
2Psec current pulse
Resistance
Tempco
Offset Straps
Resistance
Offset
Constant
Field applied in sensitive direction
Resistance
TA= -40 to 125°C
Tempco
* Tested at 25°C except stated otherwise.
Pin Configuration (Arrows indicate direction of applied field that generates a positive output voltage
after a SET pulse.)
Package Outline
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HMC1023
SENSOR PRODUCTS
Mounting Considerations
When mounting the Honeywell HMC1023 on a circuit board, please consider the following advice for ball grid array
component attachment.
Ball Grid Array attachment/removal to printed circuit boards is precisely controlled thermal solder reflow process. To
prevent internal electrical damage and package cracking, do not use conventional soldering iron/solder station tools. If
you do not have experience and the reflow oven, please have a qualified BGA rework technician do the work for you.
The reflow profile show below is the recommended profile for HMC1023 package attachment.
Melting temperature for the HMC1023 balls is at 180°C. The recommended rise and fall temperatures should be no
greater than 3°C/sec to prevent mechnical stresses or “popcorning”. Peak external temperature the part should be
exposed to is between 200 to 210°C. When exposed a high temperature, such as the solder reflow process, the
internal connections in the package could sustain permanent damage, leaving open connections. 225°C is the melting
point of solder inside the HMC1023 Ball Grid Array package. Do not expose the part to this level of temperature.
If using solder paste, we recommend Kester SN62 solder paste with water soluble flux R560. This has a melting point
around 180°C. Kester recommends a pre-heating zone from ambient temperature to 180°C for 2 to 4 minutes
maximum. The first part of this pre-heating zone ramps up from ambient to 150°C in 90 seconds with a ramp rate of
less than 2.5 degrees C per second. The soak zone should last from 60 to 90 seconds (2 minutes maximum) and
ramp up in temperature from 150 to 180°C at 0.5 to 0.6 °C/ sec. The reflow zone should last for 30 to 90 seconds
maximum (40 to 60 seconds is ideal) and peak in temperature between 200 and 210°C with a ramp of 1.3 to
1.6°C/sec.
The reflow parameters can vary significantly and excellent reflow results can still be achieved. A thin layer of paste
flux or a 2 to 3 mil layer of solder paste applied to the mother-board prior to placing the HMC1023 is helpful. The
profile can be verified by placing a thermocouple between the HMC1023 and motherboard.
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HMC1023
SENSOR PRODUCTS
Basic Device Operation
The Honeywell HMC1023 magneto-resistive sensor is composed of three Wheatstone bridge elements to measure
magnetic fields for both field strength and direction. With power applied to the bridges, the sensors elements convert
any incident magnetic field in each element’s sensitive axis direction to a differential voltage output. In addition to the
bridge elements, these sensors have two types of on-chip magnetically coupled straps; the offset straps and the
set/reset strap. These straps are Honeywell patented features for incident field adjustment and magnetic domain
alignment; and eliminate the need for external coils positioned around the sensors.
The magnetoresistive sensors are made of a nickel-iron (Permalloy) thin-film deposited on a silicon wafer and
patterned as a resistive strip element. In the presence of a magnetic field, a change in the bridge resistive elements
causes a corresponding change in voltage across the bridge outputs.
These resistive elements are aligned together to have a common sensitive axis (indicated by arrows on the pinouts)
that will provide positive voltage change with magnetic fields increasing in the sensitive direction. Because the output
only is in proportion to the one-dimensional axis (the principle of anisotropy) and its magnitude, additional sensor
bridges placed at orthogonal directions permit accurate measurement of arbitrary field direction. The combination of
sensor bridges in this three orthogonal axis configuration permit applications such as compassing and magnetometry.
The individual sensor offset straps allow for several modes of operation when a direct current is driven through it.
These modes are: 1) Subtraction (bucking) of an unwanted external magnetic field, 2) null-ing of the bridge offset
voltage, 3) Closed loop field cancellation, and 4) Auto-calibration of bridge gain.
The set/reset strap can be pulsed with high currents for the following benefits: 1) Enable the sensor to perform high
sensitivity measurements, 2) Flip the polarity of the bridge output voltage, and 3) Periodically used to improve
linearity, lower cross-axis effects, and temperature effects.
Noise Characteristics
The noise density for the HMR1023 series is around 50nV/sqrt Hz at the 1 Hz corner, and drops below 10nV/sqrt Hz
at 20Hz and begins to fit the Johnson Noise value at around 5nV/sqrt Hz beyond 100Hz. The 10Hz noise voltage
averages around 0.58 micro-volts with a 0.16 micro-volts standard deviation. These values are provided with a 5-volt
supply.
Offset Strap
The offset strap is a spiral of metalization that couples in the sensor element’s sensitive axis. In the HMC1023 design,
there is one strap per bridge with both ends brought out externally. Each offset strap measures nominally 50 ohms,
and requires about 4.6mA for each gauss of induced field. The straps will easily handle currents to buck or boost
fields through the ±6 gauss linear measurement range, but designers should note the extreme thermal heating on the
sensor die when doing so.
With most applications, the offset strap is not utilized and can be ignored. Designers can leave one or both strap
connections (Off- and Off+) open circuited, or ground one connection node. Do not tie positive and negative strap
connections together of the same strap to avoid shorted turn magnetic circuits.
Set/Reset Strap
The set/reset strap is another spiral of metalization that couples to the sensor elements easy axis (perpendicular to
the sensitive axis on the sensor die). The HMC1023 set/reset strap circuit has three straps (one per sensor) paralleled
together for operation at low voltages. The set/reset strap connections have a nominal resistance of 3.0 ohms with a
minimum required peak current of 1.5A for reset or set pulses. With rare exception, the set/reset strap must be used
to periodically condition the magnetic domains of the magneto-resistive elements for best and reliable performance.
A set pulse is defined as a positive pulse current entering the S/R+ strap connection. The successful result would be
the magnetic domains aligned in a forward easy-axis direction so that the sensor bridge’s polarity is a positive slope
with positive fields on the sensitive axis result in positive voltages across the bridge output connections.
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HMC1023
SENSOR PRODUCTS
A reset pulse is defined as a negative pulse current entering the S/R+ strap connection. The successful result would
be the magnetic domains aligned in a reverse easy-axis direction so that sensor bridge’s polarity is a negative slope
with positive fields on the sensitive axis result in negative voltages across the bridge output connections.
Typically a reset pulse is sent first, followed by a set pulse
a few milliseconds later. By shoving the magnetic domains
in completely opposite directions, any prior magnetic
disturbances are likely to be completely erased by the duet
of pulses. For simpler circuits with less critical
requirements for noise and accuracy, a single polarity
pulse circuit may be employed (all sets or all resets). With
these uni-polar pulses, several pulses together become
close in performance to a set/reset pulse circuit. Figure 1
shows a quick and dirty manual pulse circuit for uni-polar
application of pulses to the set/reset strap.
Iset
5 volts
Rsr
3.0
Figure 1
Set Pulse Circuit
Application Notes
Three Axis Compassing with Tilt Compensation
For full three-axis compassing, the circuit depicted in Figure 2 shows HMC1023 used for sensing the magnetic field
in three axes. A two-axis accelerometer with digital (PWM) outputs is also shown to provide pitch and roll (tilt)
sensing, to correct the three-axis magnetic sensors outputs into to the tilt-compensated two-axis heading. The
accelerometer can be substituted with a fluidic 2-axis tilt sensor if desired. For lower voltage operation with Lithium
battery supplies (2.5 to 3.6Vdc), the Set/Reset circuit should be upgraded from a single IRF7509 to the dual IRF7509
implementation (H-bridge) to permit a minimum 1.5-ampere pulse (500mA per set/reset strap resistance) to the
sensors.
Vcc
U1
500k
1nf
3.3 to 5.0v
Vcc
5.00k
AN0
LMV324
AN1
5.00k
AN2
U3
500k
Vcc/2
Vcc/2
HMC1023
1nf
AN3
set/reset DO0
500k
5.00k
U6
LMV324
5.00k
PC
500k
Vcc/2
.33uf
with
Multiplexed
A/D Conv.
U4
IRF7509
Vcc
U5
set/reset
Vcc
.1Pf
500k
U2
5.00k
-
LMV324
+
5.00k
Two-axis
accelerometer
500k
xout
DI0
yout
DI1
Vcc/2
Figure 7
Three Axis Compass
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HMC1023
SENSOR PRODUCTS
Duty Cycling for Lower Energy Consumption
For battery powered and other applications needing limited energy consumption, the sensor bridge and support
electronics can be switched “off” between magnetic field measurements. The HMC1023 sensors are very low
capacitance (Bandwidth > 5MHz) sensor bridges and can stabilize quickly, typically before the support electronics
can. Other energy saving ideas would be to minimize the quantity of set/reset pulses which saves energy over the
battery life. Figure 3 shows a simple supply switching circuit that can be microprocessor controlled to duty cycle
(toggle) the electronics in moderate current (<25mA) applications.
Vcc
MMBT2907ALT1
Vcc
To Sensor Circuits
0.01Pf
+
-
* Used when Vcc = 5.0 volts, jumper
when using Vcc = 3.3 volts or less.
10Pf
Gnd
PC
*MMBD7001LT1
Off
Figure 3
Duty Cycling
On
toggle
10k:
ORDERING INFORMATION
Part Number
Package Style
HMC1023
Three Axis Magnetic Sensor
HMC1023PCB
Three Axis Magnetic Sensor – 16-Pin DIP Demo
The application circuits herein constitute typical usage and interface of Honeywell product. Honeywell does not
warrant or assume liability for customer-designed circuits derived from this description or depiction.
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
This product may be covered by one or more of the following U.S. Patents: 4569742 4681812 4847584 4857418
4945397 5019461 5247278 5820924 5952825 and 6529114.
900252 10-03 Rev. B
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
1, 2 AND 3-AXIS MAGNETIC SENSORS
Features
x
x
x
x
x
Miniature Surface-Mount Packages
Wide Field Range of ± 6 Gauss
1.0 mV/V/gauss Sensitivity
Low Power Operation Down to 1.8V
Patented On-chip Set/Reset and Offset Straps
Product Description
The Honeywell HMC1051, HMC1052 and HMC1053
are high performance magnetoresistive sensor designs
on a single chip (HMC1051, HMC1052) or two chips
(HMC1053). The advantages of these patented chips
include orthogonal two-axis sensing (HMC1052), ultra
small size and low cost in miniature surface mount
packages.
Each of the magneto-resistive sensors are configured
as a 4-element wheatstone bridge to convert magnetic
fields to differential output voltages. Capable of sensing
fields down to 120 micro-gauss, these sensors offer a
compact, high sensitivity and highly reliable solution for
low field magnetic sensing.
APPLICATIONS
HMC1052 Circuit Diagram
x Compassing
x Navigation Systems
x Attitude Reference
x Traffic Detection
x Medical Devices
(9)
(3)
x Position Sensing
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions*
Min
Typ
Max
Units
Vbridge referenced to GND
1.8
3.0
20
Volts
Resistance
Bridge current = 10mA
800
1000
1500
ohms
Operating
Ambient
-40
125
°C
Ambient, unbiased
-55
150
°C
85
%
+6
gauss
Bridge Elements
Supply
Temperature
Storage
Temperature
Humidity
Field Range
Tested at 85°C
Full scale (FS) – total applied field
Linearity Error
-6
Best fit straight line
± 1 gauss
0.1
± 3 gauss
0.5
± 6 gauss
1.8
Hysteresis Error
3 sweeps across ±3 gauss
0.06
%FS
Repeatability Error
3 sweeps across ±3 gauss
0.1
%FS
Bridge Offset
Offset = (OUT+) – (OUT-)
%FS
-1.25
±0.5
+1.25
mV/V
0.8
1.0
1.2
mV/V/gauss
Field = 0 gauss after Set pulse
Sensitivity
Set/Reset Current = 0.5A
Noise Density
@ 1kHz, Vbridge=5V
50
nV/sqrt Hz
Resolution
50Hz Bandwidth, Vbridge=5V
120
Pgauss
Bandwidth
Magnetic signal (lower limit = DC)
5
MHz
Disturbing Field
Sensitivity starts to degrade.
20
gauss
Use S/R pulse to restore sensitivity.
Sensitivity
TA= -40 to 125°C, Vbridge=5V
Tempco
TA= -40 to 125°C, Ibridge=5mA
-600
Bridge Offset
TA= -40 to 125°C, No Set/Reset
±500
TA= -40 to 125°C, With Set/Reset
±10
Tempco
Bridge Ohmic
Vbridge=5V, TA= -40 to 125°C
-3000
2100
-2700
2500
-2400
ppm/°C
ppm/°C
2900
ppm/°C
Tempco
Cross-Axis Effect
Max. Exposed
Cross field = 1 gauss, Happlied = ±1 gauss
±3
No perming effect on zero reading
%FS
10000
gauss
105
%
0.01
degree
Field
Sensitivity Ratio of
TA= -40 to 125°C
95
100
X,Y Sensors
(HMC1052 Only)
X,Y sensor
Sensitive direction in X and Y sensors
Orthogonality
(HMC1052)
* Tested at 25°C except stated otherwise.
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions*
Min
Typ
Max
Units
Measured from S/R+ to S/R-
3
4.5
6
ohms
0.1% duty cycle, or less,
0.4
0.5
4
Amp
TA= -40 to 125°C
3300
3700
4100
ppm/°C
Measured from OFFSET+ to OFFSET-
12
15
18
ohms
Set/Reset Strap
Resistance
Current
2Psec current pulse
Resistance
Tempco
Offset Straps
Resistance
Offset
DC Current
Constant
10
mA/gauss
Field applied in sensitive direction
Resistance
TA= -40 to 125°C
3500
3900
4300
ppm/°C
Tempco
* Tested at 25°C except stated otherwise.
PIN CONFIGURATIONS
(Arrow indicates direction of applied field that generates a positive
output voltage after a SET pulse.)
HMC1051
Vcc
(3)
HMC1051Z Pinout
HMC1051
HONEYWELL
HMC1051Z
BRIDGE A
BRIDGE B
1 2 3 4 5 6 7 8
Vo+(A)
(2)
GND Plane
(4)
Vo-(A)
(8)
GND1(B) GND2(B)
(1)
(5)
Set/Reset Strap
S/R+
(6)
S/R(7)
HMC1051ZL
HMC1051ZL Pinout
8
VB
7
6
5
4
3
2
1
VO+ OFF+ GND VO- S/R- S/R+ OFF-
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
HMC1052
HMC1052 Pinout
Vcc
(5)
10
9
8
7
6
HMC1052
B
BRIDGE A
OUT(10)
GND2 GND1
(9)
(3)
HMC
1052
BRIDGE B
OUT+
(4)
OUT(7)
GND
(1)
A
OUT+
(2)
1
2
3
4
5
Set/Reset Strap
S/R+
(6)
S/R(8)
HMC1052L
HMC1052L Pinout
HMC1053
HMC1053 Pinout
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
PACKAGE OUTLINES
PACKAGE DRAWING HMC1051Z (8-PIN SIP)
Symbol
Millimeters
Min
Max
1.371
1.728
0.101
0.249
0.355
0.483
9.829
11.253
3.810
3.988
1.270 ref
6.850
7.300
0.381
0.762
Inches x 10E-3
Min
Max
54
68
4
10
14
19
387
443
150
157
50 ref
270
287
15
30
Symbol
Millimeters
Min
Max
Inches x 10E-3
Min
Max
A
A1
B
D
E1
e
E
L1
1.10
0.05
0.15
0.15
0.30
2.90
3.10
2.90
3.10
0.50 BSC
4.75
5.05
0.95 BSC
2.0
5.9
114
114
2.0 BSC
187
37.4
A
A1
B
D
E
e
H
h
PACKAGE DRAWING HMC1051ZL (8-PIN IN-LINE LCC)
PACKAGE DRAWING HMC1052 (10-PIN MSOP)
43
5.9
11.8
122
122
199
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
PACKAGE DRAWING HMC1052L (16-PIN LCC)
Symbol
A
A1
A3
b
D
D2
E
E2
e
L
N
ND
NE
r
aaa
bbb
ccc
Millimeters
min
max
0.80
1.00
0
0.05
0.20 REF
0.18
0.30
3.00 BSC
1.55
1.80
3.00 BSC
1.55
1.80
0.50 BSC
0.30
0.50
16
4
4
B(min)/2
0.15
0.10
0.10
PACKAGE DRAWING HMC1053 (16-PIN LCC)
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
Basic Device Operation
The Honeywell HMC105X family of magnetoresistive
sensors are Wheatstone bridge devices to measure
magnetic fields. With power supply applied to a bridge,
the sensor converts any incident magnetic field in the
sensitive axis direction to a differential voltage output.
In addition to the bridge circuit, the sensor has two onchip magnetically coupled straps; the offset strap and
the set/reset strap. These straps are Honeywell
patented features for incident field adjustment and
magnetic domain alignment; and eliminate the need
for external coils positioned around the sensors.
The magnetoresistive sensors are made of a nickeliron (Permalloy) thin-film deposited on a silicon wafer
and patterned as a resistive strip element. In the
presence of a magnetic field, a change in the bridge
resistive elements causes a corresponding change in
voltage across the bridge outputs.
These resistive elements are aligned together to have
a common sensitive axis (indicated by arrows on the
pinouts) that will provide positive voltage change with
magnetic fields increasing in the sensitive direction.
Because the output only is in proportion to the onedimensional axis (the principle of anisotropy) and its
magnitude, additional sensor bridges placed at
orthogonal directions permit accurate measurement of
arbitrary field direction. The combination of sensor
bridges in two and three orthogonal axis permit
applications such as compassing and magnetometry.
Cross-Axis Effect
Cross-Axis effect for the HMR105X series is typically
specified at ±3% of full scale to 1 gauss. See
application note AN215 regarding this effect and
methods for nulling.
Offset Strap
The offset strap is a spiral of metalization that couples
in the sensor element’s sensitive axis. In two-axis
designs, the strap is common to both bridges and must
be multiplexed if each bridge requires a different strap
current. In three-axis designs, the A and B bridges are
together with the C bridge sharing a common node for
series driving all three bridges’ offset straps. Each
offset strap measures nominally 15 ohms, and
requires 10mA for each gauss of induced field. The
straps will easily handle currents to buck or boost
fields through the ±6 gauss linear measurement range,
but designers should note the extreme thermal heating
on the die when doing so.
With most applications, the offset strap is not utilized
and can be ignored. Designers can leave one or both
strap connections (Off- and Off+) open circuited, or
ground one connection node. Do not tie both strap
connections together to avoid shorted turn magnetic
circuits.
Set/Reset Strap
The offset strap allows for several modes of operation
when a direct current is driven through it. These
modes are: 1) Subtraction (bucking) of an unwanted
external magnetic field, 2) null-ing of the bridge offset
voltage, 3) Closed loop field cancellation, and 4) Autocalibration of bridge gain.
The set/reset strap can be pulsed with high currents
for the following benefits: 1) Enable the sensor to
perform high sensitivity measurements, 2) Flip the
polarity of the bridge output voltage, and 3)
Periodically used to improve linearity, lower cross-axis
effects, and temperature effects.
Noise Characteristics
The noise density for the HMR105X series is around
50nV/sqrt Hz at the 1 Hz corner, and quickly drops
below 10nV/sqrt Hz at 5Hz and begins to fit the
Johnson Noise value at just below 5nV/sqrt Hz beyond
50Hz. The 10Hz noise voltage averages around 1.4
micro-volts with a 0.8 micro-volts standard deviation.
The set/reset strap is another spiral of metalization
that couples to the sensor elements easy axis
(perpendicular to the sensitive axis on the sensor die).
Like the offset strap, the set/reset strap runs through a
pair of bridge elements to keep the overall die size
compact. Each set/reset strap has a nominal
resistance of 3 to 6 ohms with a minimum required
peak current of 400mA for reset or set pulses. With
rare exception, the set/reset strap must be used to
periodically condition the magnetic domains of the
magneto-resistive elements for best and reliable
performance.
A set pulse is defined as a positive pulse current
entering the S/R+ strap connection. The successful
result would be the magnetic domains aligned in a
forward easy-axis direction so that the sensor bridge’s
polarity is a positive slope with positive fields on the
sensitive axis result in positive voltages across the
bridge output connections.
A reset pulse is defined as a negative pulse current
entering the S/R+ strap connection. The successful
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
accuracy, a single polarity pulse circuit may be
employed (all sets or all resets). With these uni-polar
pulses, several pulses together become close in
performance to a set/reset pulse circuit. Figure 1
shows a quick and dirty manual pulse circuit for unipolar application of pulses to the set/reset strap.
result would be the magnetic domains aligned in a
reverse easy-axis direction so that sensor bridge’s
polarity is a negative slope with positive fields on the
sensitive axis result in negative voltages across the
bridge output connections.
Typically a reset pulse is sent first, followed by a set
pulse a few milliseconds later. By shoving the
magnetic domains in completely opposite directions,
any prior magnetic disturbances are likely to be
completely erased by the duet of pulses. For simpler
circuits with less critical requirements for noise and
Iset
5 volts
Application Notes
Figure 1
Set Pulse Circuit
Low Cost 2-Axis Compass
Very high precision measurements can be made using the HMC105X family of sensors when interfaced with low
noise amplifiers and 12 to 16-bit Analog-to-Digital (A/D) converters. For lower resolution (3° accuracy or more) or low
cost compass applications, 8 or 10-bit A/D converters may be used with general purpose operational amplifiers.
Figure 2 shows a typical 2-axis compassing application using readily available off-the-shelf components.
The basic principle of two-axis compassing is to orient the two sensor bridge elements horizontal to the ground
(perpendicular to the gravitational field) and to measure the resulting X and Y analog output voltages. With the
amplified sensor bridge voltages near-simultaneously converted (measured) to their digital equivalents, the arctangent Y/X can be computed to derive the heading information relative to the X-axis sensitive direction. See the
application notes on compassing at Honeywell Magnetic Sensors website (www.magneticsensors.com) for basic
principles and detailed application information.
U1
1nf
Vcc
500k
2.5 to 3.6v
5.00k
LMV358
5.00k
U3
500k
Vref/2
U2
HMC1052
1nf
500k
enable
1
MAX1118
data_out
clk_in
0
Vref
5.00k
LMV358
5.00k
500k
Vref/2
set/reset
.1uf
U4
(2) IRF7509
offset
U5
set/reset
Figure 2
Two-Axis Compass
_set/reset
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
Set/Reset Circuit Notes
The above set/reset circuit in Figure 1using the
IRF7507 dual complementary MOSFETs is shown in
detail by Figure 2 in its H-bridge driven configuration.
This configuration is used primarily in battery operated
applications were the 500mA nominal set/reset pulsed
currents can be best obtained under low voltage
conditions.
Vsr
1Pf
200:
S
-
IRF7509(P)
G
.1Pf
D
set/reset
D
The 200-ohm resistor trickle charges the 1uf supply
reservoir capacitor to the Vcc level, and isolates the
battery from the high current action of the capacitors
and MOSFET switches. Under conventional logic states
one totem pole switch holds one node of the 0.1uf
capacitor low, while the other switch charges Vcc into
the capacitors opposite node. At the first logic change,
the capacitor exhibits almost a twice Vcc flip of polarity,
giving the series set/reset strap load plenty of pulse
current. A restoring logic state flip uses the 0.1uf
capacitors stored energy to create a second nearly
equal but opposite polarity current pulse through the
set/reset strap.
G
Vsr
Rset/reset
S
IRF7509(P)
S
4:
IRF7509(N)
G
D
_set/reset
D
G
S
Figure 3
H-Bridge Driver
IRF7509(N)
Vsr
For operation at normal 3.3 or 5-volt logic levels, a
single complementary MOSFET pair can be used in a
single ended circuit shown in Figure 4. Other
complementary MOSFET pairs can be used with the
caution that the chosen devices should have less than
0.5 ohms ON resistance and be able to handle the
needed supply voltages and set/reset currents. Note
that even a 1Hz rate of set/reset function draws an
average current of less than 2 microamperes.
Vcc
+
1Pf
200:
Vcc
+
S
-
IRF7509(P)
G
.1Pf
D
set/reset
D
G
Rset/reset
4:
S
IRF7509(N)
Figure 4
Single-Ended Driver
Magnetic Field Detection
For simple magnetic field sensing applications such Magnetic Anomaly Detectors (MADs) and Magnetometers, a
similar circuit to the compass application can be implemented using one, two, or three magnetic sensors. In the
example circuit in Figure 5, a HMC1051Z sensor bridge is used with a low voltage capable dual op-amp to detect
sufficient intensity of a magnetic field in a single direction. Uses of the circuit include ferrous object detection such as
vehicle detection, a “sniffer” for currents in nearby conductors, and magnetic proximity switching. By using two or
three sensor circuits with HMC1051, HMC1052, or HMC1053 parts, a more omni-directional sensing pattern can be
implemented. There is nothing special in choosing the resistors for the differential op-amp gain stages other than
having like values (e.g. the two 5k: and the 500k: resistors) matched at 1% tolerance or better to reject commonmode interference signals (EMI, RFI). The ratio of the 500k:/5k: resistors sets the stage gain and can be optimized
for a specific purpose. Typical gain ratios for compass and magnetometer circuits using the HMC105X family, range
from 50 to 500. The choice of the 5k: value sets impedance loading seen by the sensor bridge network and should
be about 4 kilo-ohms or higher for best voltage transfer or matching. Note that Figure 5 also shows an alternative
set/reset strap driver circuit using two darlington complentary paired BJTs as electronic switches.
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
U1
Vcc
.1Pf
Vcc
500k
5.0v
5.00k
10k: pot
Threshold Set
- TLC072
+
5.00k
U2
500k
output
- TLC072
+
Vcc/2
LED
HMC1051
10k:
Vcc
* Low ESR Tantalum
RLED
200:
1Pf*
- +
10k:
0.1Pf
FMMT717
.1uf
set/reset
set/reset
FMMT617
S
0.1Pf
offset
R
Figure 5
Magnetic Field Detector
10k:
Alternating or Direct Current Sensing
The HMC105X family sensors can be utilized in a novel way for moderate to high current sensing applications using
a nearby external conductor providing the sensed magnetic field to the bridge. Figure 6 shows a HMC1051Z used as
a current sensor with thermistor element performing a temperature compensation function for greater accuracy over
a wide range of operational temperatures. Selection of the temperature compensation (tempco) resistors used
depends on the thermistor chosen and is dependant on the thermistor’s %/°C shift of resistance. For best op-amp
compatibility, the thermistor resistance should be above about 1000 ohms. The use of a 9-volt alkaline battery supply
is not critical to this application, but permits fairly common operational amplifiers such as the 4558 types to be used.
Note that the circuit must be calibrated based on the final displacement of the sensed conductor to the measuring
bridge. Typically, an optimally oriented measurement conductor can be placed about one centimeter away from the
bridge and have reasonable capability of measuring from tens of milliamperes to beyond 20 amperes of alternating or
direct currents. See application note AN-209 for the basic principles of current sensing using AMR bridges.
tempco
network
Rb
standoff distance
U1
Vcc = 9Vdc
.1Pf
Rth
500k
-
5.00k
-
RC4558
+
+
5.00k
Ra
RC4458
output
U2
500k
Figure 6
Current Sensor
Vcc/2 ~ +4.5Vdc
HMC1051
Vcc =9Vdc
* Low ESR Tantalum
200:
1Pf*
- +
Iac
Idc
set/reset
.1uf
set/reset
Si1553DL
offset
U3
Conductor to be
Current Measured
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
Three Axis Compassing with Tilt Compensation
For full three-axis compassing, the circuit depicted in Figure 7 shows both a HMC1051 and a HMC1052 used for
sensing the magnetic field in three axes. Alternatively a single HMC1053 could be used for a single sensor package
design. A two-axis accelerometer with digital (PWM) outputs is also shown to provide pitch and roll (tilt) sensing, to
correct the three-axis magnetic sensors outputs into to the tilt-compensated two-axis heading. The accelerometer
can be substituted with a fluidic 2-axis tilt sensor if desired. For lower voltage operation with Lithium battery supplies
(2.5 to 3.6Vdc), the Set/Reset circuit should be upgraded from a single IRF7507 to the dual IRF7507 implementation
(per Figure 2) to permit a minimum 1-ampere pulse (500mA per set/reset strap resistance) to both the HMC1052 and
HMC1051 sensors.
U1
Vcc
1nf
500k
3.3 to 5.0v
Vcc
5.00k
AN0
LMV324
AN1
5.00k
AN2
U3
500k
Vcc/2
Vcc/2
HMC1052
1nf
AN3
set/reset DO0
500k
5.00k
U6
LMV324
5.00k
PC
500k
Vcc/2
.1uf
set/reset
with
Multiplexed
A/D Conv.
U4
IRF7509
Vcc
offset
U5
set/reset
Vcc
.1Pf
500k
Two-axis
accelerometer
U2
5.00k
-
LMV324
+
5.00k
xout
DI0
yout
DI1
500k
Vcc/2
HMC1051
Figure 7
Three Axis Compass
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HMC1051/HMC1052/HMC1053
SENSOR PRODUCTS
Duty Cycling for Lower Energy Consumption
For battery powered and other applications needing limited energy consumption, the sensor bridge and support
electronics can be switched “off” between magnetic field measurements. The HMC105X family of magnetic sensors
are very low capacitance (Bandwidth > 5MHz) sensor bridges and can stabilize quickly, typically before the support
electronics can. Other energy saving ideas would be to minimize the quantity of set/reset pulses which saves energy
over the battery life. Figure 8 shows a simple supply switching circuit that can be microprocessor controlled to duty
cycle (toggle) the electronics in moderate current (<25mA) applications.
Vcc
MMBT2907ALT1
Vcc
To Sensor Circuits
0.01Pf
+
-
* Used when Vcc = 5.0 volts, jumper
when using Vcc = 3.3 volts or less.
10Pf
Gnd
PC
*MMBD7001LT1
Off
Figure 8
Duty Cycling
On
toggle
10k:
ORDERING INFORMATION
Part Number
Package Style
HMC1051Z
One Axis Magnetic Sensor – SIP8
HMC1051ZL
One Axis Magnetic Sensor – 8-PIN IN-LINE LCC
HMC1052
Two Axis Magnetic Sensors – MSOP10
HMC1052L
Two Axis Magnetic Sensors – 16-PIN LCC
HMC1053
Three Axis Magnetic Sensors – 16-PIN LCC
The application circuits herein constitute typical usage and interface of Honeywell product. Honeywell does not
warrant or assume liability for customer-designed circuits derived from this description or depiction.
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
This product may be covered by one or more of the following U.S. Patents: 4569742 4681812 4847584 4857418
4945397 5019461 5247278 5820924 5952825 and 6529114.
900308 10-03 Rev. -
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HMC1055
Advance Information
SENSOR PRODUCTS
3-AXIS COMPASS SENSOR SET
Features
x
x
x
x
x
x
3 Precision Sensor Components
2-Axis Magnetoresistive Sensor for X-Y Axis
Earth’s Field Detection
1-Axis Magnetoresistive Sensor for Z-Axis Earth’s
Field Detection
2-Axis Accelerometer for 60° Tilt Compensation
2.7 to 5.5 volt Supply Range
3-Axis Compass Reference Design Included
Product Description
The Honeywell HMC1055 3-Axis Compass Sensor Set
combines the popular HMC1051Z one-axis and the
HMC1052 two-axis magneto-resistive sensors plus a 2axis MEMSIC MXS3334UL accelerometer in a single
kit. By combining these three sensor packages, OEM
compass system designers will have the building
blocks needed to create their own tilt compensated
compass designs using these proven components.
The HMC1055 chip set includes the three sensor
integrated circuits and an application note describing
sensor function, a reference design, and design tips for
integrating the compass feature into other product
platforms.
DIAGRAMS
Pinouts (top view)
10
9
8
7
6
HONEYWELL
HMC1051Z
B
HMC
1052
A
1 2 3 4 5 6 7 8
1
2
3
4
5
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HMC1055
Advance Information
SPECIFICATIONS – MAGNETIC SENSORS HMC1051Z, HMC1052
Characteristics
SENSOR PRODUCTS
Conditions*
Min
Typ
Max
Units
Vbridge referenced to GND
1.8
2.5
20
Volts
Resistance
Bridge current = 1mA
800
1000
1500
ohms
Field Range
Full scale (FS) – total applied field
-6
+6
gauss
Sensitivity
Set/Reset Current = 0.5A
0.8
1.0
1.2
mV/V/gauss
Bridge Offset
Offset = (OUT+) – (OUT-)
-1.25
±0.5
+1.25
mV/V
Bridge Elements
Supply
Field = 0 gauss after Set pulse
Bandwidth
Magnetic signal (lower limit = DC)
5
MHz
@ 1kHz, Vbridge=5V
50
nV/sqrt Hz
Resolution
50Hz Bandwidth, Vbridge=5V
120
Pgauss
Disturbing Field
Sensitivity starts to degrade.
Noise Density
20
gauss
Use S/R pulse to restore sensitivity.
Max. Exposed
No perming effect on zero reading
10000
gauss
Field
Operating
Ambient
-40
125
°C
Ambient, unbiased
-55
150
°C
Sensitivity
TA=-40 to 125°C, Vbridge=5V
-3000
-2400
ppm/°C
Tempco
TA=-40 to 125°C, Ibridge=5mA
-600
Bridge Offset
TA=-40 to 125°C, No Set/Reset
±500
TA=-40 to 125°C, With Set/Reset
±10
Temperature
Storage
Temperature
Tempco
Bridge Ohmic
-2700
ppm/°C
Vbridge=5V, TA=-40 to 125°C
2100
2500
2900
ppm/°C
TA=-40 to 125°C
95
101
105
%
0.01
degree
Tempco
Sensitivity Ratio of
X,Y Sensors
(HMC1052 Only)
X,Y sensor
Sensitive direction in X and Y sensors
Orthogonality
(HMC1052)
Linearity Error
Best fit straight line
± 1 gauss
0.1
± 3 gauss
0.5
± 6 gauss
1.8
3 sweeps across ±3 gauss
0.06
%FS
Repeatability Error
3 sweeps across ±3 gauss
* Tested at 25°C except stated otherwise.
0.1
%FS
Hysteresis Error
%FS
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HMC1055
Advance Information
SPECIFICATIONS – MAGNETIC SENSORS HMC1051Z, HMC1052
Characteristics
Conditions*
SENSOR PRODUCTS
Min
Typ
Max
Units
Measured from S/R+ to S/R-
3
4
5
ohms
0.1% duty cycle, or less,
0.4
0.5
4
Amp
Set/Reset Strap
Resistance
Current
2Psec current pulse
Resistance
TA= -40 to 125°C
3700
ppm/°C
Tempco
Offset Straps
Resistance
(available on die)
Measured from OFFSET+ to OFFSET-
Offset
Constant
12
DC Current
15
18
ohms
10
mA/gauss
3900
ppm/°C
Field applied in sensitive direction
Resistance
TA= -40 to 125°C
Tempco
* Tested at 25°C except stated otherwise.
SPECIFICATIONS – ACCELEROMETER MXS3334UL
Characteristics
Conditions*
Min
Typ
Max
Units
Sensor Input
Range
±1
Non-Linearity
Best fit straight line
g
0.5
1.0
% of FS
Alignement Error
±1.0
degree
Transverse
±2.0
%
Sensitivity
Sensitivity
(Each Axis)
Digital Outputs
Vdd = 5.0 volts
Change Over
Temperature
19.00
20.00
-40°C, Uncompensated
+105°C, Uncompensated
21.00
%Duty
Cycle/g
+100
%
-50
Compensated (-40°C to +105°C)
< 3.0
' from 25°C
Resistance
Zero g Bias Level
TA= -40 to 125°C
3900
ppm/°C
(Each Axis)
0 g Offset
-0.1
0.00
+0.1
g
0 g Duty Cycle
48
50
52
% Duty Cycle
0 g Offset Over
Temperature
' from 25°C
±0.75
mg/°C
' from 25°C, based on 20%/g
±0.015
%/°C
rms
0.2
3dB Bandwidth
25
Performance
Noise Density
Frequency
0.4
mg/sqrt-Hz
Hz
Response
Tested at 25°C except stated otherwise.
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HMC1055
Advance Information
MXS3334UL SPECIFICATIONS
Characteristics
SENSOR PRODUCTS
Conditions*
Min
Typ
Max
Units
Vdd = 2.7 to 5.0
2.4
2.5
2.65
volts
Voltage Reference
Vref
Change Over
0.1
mV/°C
Temperature
Current Drive
Source
100
PA
Capability
Self Test
Continuous
Voltage Under
Vdd = 5.0 volts, DOUTX and DOUTY
5.0
Vdd = 2.7 volts, DOUTX and DOUTY
2.7
volts
Failure
(DOUTX and DOUTY)
Digital Outputs
Normal Range
Current
Vdd = 5.00 volts
0.1
4.9
Vdd = 2.7 volts
0.1
2.6
Source or Sink (Vdd =2.7 to 5.0v)
volts
100
Rise/Fall Time
Vdd = 2.7 to 5.0 volts
90
100
Turn-On Time
Vdd = 5.0 volts
100
Vdd = 2.7 volts
40
PA
110
Ksec
msec
Power Supply
Operating Voltage
2.7
5.25
volts
mA
Range
Supply Current
Vdd = 5.0 volts
3.0
3.6
4.2
Vdd = 2.7 volts
4.0
4.9
5.8
Temperature
Operating Range
Storage Range
Tested at 25°C except stated otherwise.
Pin Configurations
-40
+105
°C
-65
+150
°C
(Arrow indicates direction of applied field that generates a positive output voltage after a SET pulse.)
HMC1051
Vcc
(3)
HMC1051Z Pinout
HMC1051
HONEYWELL
HMC1051Z
BRIDGE A
BRIDGE B
1 2 3 4 5 6 7 8
Vo+(A)
(2)
GND Plane
(4)
Vo-(A)
(8)
GND1(B) GND2(B)
(1)
(5)
Set/Reset Strap
S/R+
(6)
S/R(7)
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HMC1055
Advance Information
HMC1052
SENSOR PRODUCTS
HMC1052 Pinout
Vcc
(5)
10
9
8
7
6
HMC1052
B
BRIDGE A
OUT(10)
HMC
1052
BRIDGE B
GND2 GND1
(9)
(3)
OUT+
(4)
OUT(7)
GND
(1)
A
OUT+
(2)
1
2
3
4
5
Set/Reset Strap
S/R+
(6)
S/R(8)
MXD3334UL
Sck
(optional)
Internal
Oscillator
CLK
Temperature
Sensor
TOUT
(1)
Voltage
Reference
VREF
(6)
8
Continous
Self Test
Heater
Control
7
2
Low Pass
Filter
X axis
1
M E M S IC
(7)
DOUTX
(5)
3
X +g
6
5
4
Factory Adjust
Offset & Gain
Y +g
Low Pass
Filter
Y axis
2-AXIS
SENSOR
VDD
Gnd
VDA
(8)
(3)
(4)
DOUTY
(2)
Top View
Pin Descriptions
HMC1051Z
Pin
Name
1
GND1(B)
2
Vo+(A)
3
Vcc
4
GND Plane
5
GND2(B)
6
S/R+
7
S/R8
Vo-(A)
Description
Bridge B Ground 1 (normally left open)
Bridge Output Positive
Bridge Positive Supply
Bridge Ground (substrate)
Bridge B Ground 2 (normally left open)
Set/Reset Strap Positive
Set/Reset Strap Negative
Bridge Output Negative
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HMC1055
Advance Information
HMC1052
Pin
Name
1
GND
2
OUT+
3
GND1
4
OUT+
5
Vcc
6
S/R+
7
OUT8
S/R9
GND2
10
OUT-
SENSOR PRODUCTS
Description
Bridge B Ground
Bridge B Output Positive
Bridge A Ground 1
Bridge B Output Positive
Bridge Positive Supply
Set/Reset Strap Positive
Bridge B Output Negative
Set/Reset Strap Negative
Bridge A Ground 2
Bridge A Output Negative
MXD3334UL
Pin
Name
1
TOUT
2
DOUTY
3
Gnd
4
VDA
5
DOUTX
6
Vref
7
Sck
8
VDD
Description
Temperature (Analog Voltage)
Y-Axis Acceleration Digital Signal
Ground
Analog Supply Voltage
X-Axis Acceleration Digital Signal
2.5V Reference
Optional External Clock
Digital Supply Voltage
Package Dimensions
HMC1051Z
Symbol
Millimeters
Min
Max
1.371
1.728
0.101
0.249
0.355
0.483
9.829
11.253
3.810
3.988
1.270 ref
6.850
7.300
0.381
0.762
Inches x 10E-3
Min
Max
54
68
4
10
14
19
387
443
150
157
50 ref
270
287
15
30
Symbol
Millimeters
Min
Max
Inches x 10E-3
Min
Max
A
A1
B
D
E1
e
E
L1
1.10
0.05
0.15
0.15
0.30
2.90
3.10
2.90
3.10
0.50 BSC
4.75
5.05
0.95 BSC
2.0
5.9
114
114
2.0 BSC
187
37.4
A
A1
B
D
E
e
H
h
HMC1052
43
5.9
11.8
122
122
199
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HMC1055
Advance Information
MXS3334UL
SENSOR PRODUCTS
Application Notes
The HMC1055 Chipset is composed of three sensors packaged as integrated circuits for tilt compensated electronic
compass development. These three sensors are composed of a Honeywell HMC1052 two-axis magnetic field sensor,
a Honeywell HMC1051Z one-axis magnetic sensor, and the Memsic MXS3334UL two-axis accelerometer.
Traditionally, compassing is done with a two-axis magnetic sensor held level (perpendicular to the gravitational axis)
to sense the horizontal vector components of the earth’s magnetic field from the south pole to the north pole. By
incorporating a third axis magnetic sensor and the two-axis accelerometer to measure pitch and roll (tilt), the compass
is able to be electronically “gimbaled” and can point to the north pole regardless of level.
The HMC1052 two-axis magnetic sensor contains two Anisotropic Magneto-Resistive (AMR) sensor elements in a
single MSOP-10 package. Each element is a full wheatstone bridge sensor that varies the resistance of the bridge
magneto-resistors in proportion to the vector magnetic field component on its sensitive axis. The two bridges on the
HMC1052 are orientated orthogonal to each other so that a two-dimensional representation of an magnetic field can
be measured. The bridges have a common positive bridge power supply connection (Vb); and with all the bridge
ground connections tied together, form the complete two-axis magnetic sensor. Each bridge has about an 1100-ohm
load resistance, so each bridge will draw several milli-amperes of current from typical digital power supplies. The
bridge output pins will present a differential output voltage in proportion to the exposed magnetic field strength and the
amount of voltage supply across the bridge. Because the total earth’s magnetic field strength is very small (~0.6
gauss), each bridge’s vector component of the earth’s field will even be smaller and yield only a couple milli-volts with
nominal bridge supply values. An instrumentation amplifier circuit; to interface with the differential bridge outputs, and
to amplify the sensor signal by hundreds of times, will then follow each bridge voltage output.
The HMC1051Z is an additional magnetic sensor in an 8-pin SIP package to place the sensor silicon die in a vertical
orientation relative to a Printed Circuit Board (PCB) position. By having the HMC1052 placed flat (horizontal) on the
PCB and the HMC1051Z vertical, all three vector components of the earth’s magnetic field (X, Y, and Z) are sensed.
By having the Z-axis component of the field, the electronic compass can be oriented arbitrarily; and with a tilt sensor,
perform tilt-compensated compass heading measurements as if the PCB where perfectly level.
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HMC1055
Advance Information
SENSOR PRODUCTS
C1
150P
Vdd
R1A
7
R1
1.00MEG
R2A
R2
4.99K
6
1
VCC
5
VEE
X1
LMV324M
2
R4
4.99K
R3A
DO0
Vdd
Vdd
R4A
R3
1.00MEG
VDD
R12
10K
Vref
C2
150P
HMC1052
R1B
10
R6
4.99K
11
R13
10K
AN1
VCC
VEE
12
R8
4.99K
R4B
AN0
Vdd
13
R3B
14
AN2
X2
LMV324M
AN3
C6
0.1U
R7
1.00MEG
C4
1U
R9
220
8
18
VDD VREF VDA
15
X4
IRF7509P
X5
IRF7509N
16
Rsr2
4
DOUTY
MXS3334UL
TOUT
HMC1051Z
C5
150P
Vdd
22
R15Z
R19
4.99K
21
24
SCK
VCC
VEE
R21
4.99K
R20
1.00MEG
R17Z
GND
Vdd
23
R16Z
NC
DOUTX
R18
1.00MEG
R14Z
DI1
NC
9
C3
0.22U
GND
R10
10
C7
0.1U
Vdd
DI0
Vdd
Vref
Rsr1
4
SCK
CS
RXD
TXD
Vref
R5
1.00MEG
R2B
MICROCONTROLLER
25
X3
LMV324M
Figure 1
3-Axis Compass Reference Design
Vref
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SENSOR PRODUCTS
The MXS3334UL is a two-axis accelerometer in an 8-pin LCC package that provides a digital representation of the
earth’s gravitational field. When the MXS3334UL is held level and placed horizontally on a PCB, both digital outputs
provide a 100 Hz Pulse Width Modulated (PWM) square wave with a 50 percent duty cycle. As the accelerometer is
pitched or rolled from horizontal to vertical, the Doutx and Douty duty cycles will shift plus or minus 20% of its duty
from the 50% center point.
The reference design in Figure 1 shows a reference design incorporating all three sensor elements of the HMC1055
chipset for a tilt compensated electronic compass operating from a 5.0 volt regulated power supply described as Vdd.
The HMC1052 sensor bridge elements A and B are called out as R1A, R2A, R3A, R4A, and R1B, R2B, R3B, R4B
respectively; and create a voltage dividing networks that place nominally 2.5 volts into the succeeding amplifier
stages. The HMC1051Z sensor bridge elements R14Z, R15Z, R16Z, and R17Z also do a similar voltage dividing
method to its amplifier stage.
In this design each amplifier stage uses a single operational amplifier (op-amp) from a common LMV324M quad opamp Integrated Circuit (IC). For example, resistors R1, R2, R3, and R4 plus capacitor C1 configure op-amp X1 into an
instrumentation amplifier with a voltage gain of about 200. These instrumentation amplifier circuits take the voltage
differences in the sensor bridges, and amplify the signals for presentation at the micro-controller Analog to Digital
Converter (ADC) inputs, denoted as AN1, AN2, and AN3. Because the zero magnetic field reference level is at 2.5
volts, each instrumentation amplifier circuit receives a 2.5 volt reference voltage (Vref) from a resistor divider circuit
composed of R12 and R13.
For example, a +500 milli-gauss earth’s field on bridge A of the HMC1052 will create a 2.5 milli-volt difference voltage
at the sensor bridge output pins (0.5 gauss multiplied by the 1.0mV/V/gauss sensitivity rating). This 2.5mV then is
multiplied by 200 for 0.5 volt offset that is referenced to the 2.5 volt Vref for a total of +3.0 volts at AN1. Likewise any
positive and or negative magnetic field vectors from bridge B and the HMC1051Z bridge are converted to voltage
representations at AN2 and AN3.
The micro-controller also receives the sensor inputs from the MXS3334UL accelerometer directly from Doutx and
Douty into two digital inputs denoted as DI0 and DI1. Optionally, the MXS3334UL temperature output pin (Tout) can
routed to another microcontroller ADC input for further temperature compensation of sensor inputs. Power is supplied
to the MXS3334UL from the 5.0 volt Vdd source directly to the accelerometer VDA pin and on to the VDD pin via a ten
ohm resistor (R10) for modest digital noise decoupling. Capacitors C6 and C7 provide noise filtering locally at the
accelerometer and throughout the compass circuit.
The set/reset circuit for this electronic compass is composed of MOSFETs X4 and X5, capacitors C3 and C4, and
resistor R9. The purpose of the set/reset circuit is to re-align the magnetic moments in the magnetic sensor bridges
when they exposed to intense magnetic fields such as speaker magnets, magnetized hand tools, or high current
conductors such as welding cables or power service feeders. The set/reset circuit is toggled by the microcontroller
and each logic state transition creates a high current pulse in the set/reset straps for both HMC1052 and the
HMC1051Z.
Operational Details
With the compass circuitry fully powered up, sensor bridge A creates a voltage difference across OUTA- and OUTA+
that is then amplified 200 times and presented to microcontroller analog input AN1. Similarly, bridges B and C create
a voltage difference that is amplified 200 times and presented to microcontroller analog inputs AN2 and AN3. These
analog voltages at AN1 and AN2 can be thought of as “X” and “Y” vector representations of the magnetic field. The
third analog voltage (AN3) plus the tilt information from accelerometer, is added to the X and Y values to create tilt
compensated X and Y values, sometimes designated X’ and Y’.
To get these X, Y, and Z values extracted, the voltages at AN1 through AN3 are to be digitized by the
microcontroller’s onboard Analog-to-Digital Converter (ADC). Depending on the resolution of the ADC, the resolution
of the Compass is set. Typically compasses with one degree increment displays will have 10-bit or greater ADCs, with
8-bit ADCs more appropriate for basic 8-cardinal point (North, South, East, West, and the diagonal points)
compassing. Individual microcontroller choices have a great amount of differing ADC implementations, and there may
be instances where the ADC reference voltage and the compass reference voltage can be shared. The point to
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SENSOR PRODUCTS
remember is that the analog voltage outputs are referenced to half the supplied bridge voltage and amplified with a
similar reference.
The most often asked question on AMR compass circuits is how frequent the set/reset strap must be pulsed. The
answer for most low cost compasses is fairly infrequently; from a range of once per second, to once per compass
menu selection by the user. While the set circuit draws little energy on a per pulse basis, a constant one pulse per
second rate could draw down a fresh watch battery in less than a year. In the other extreme of one “set” pulse upon
the user manually requesting a compass heading, negligible battery life impact could be expected. From a common
sense standpoint, the set pulse interval should be chosen as the shortest time a user could withstand an inaccurate
compass heading after exposing the compass circuit to nearby large magnetic sources. Typical automatic set
intervals for low cost compasses could be once per 10 seconds to one per hour depending on battery energy
capacity. Provision for a user commanded “set” function may be a handy alternative to periodic or automatic set
routines.
In portable consumer electronic applications like compass-watches, PDAs, and wireless phones; choosing the
appropriate compass heading data flow has a large impact on circuit energy consumption. For example, a one
heading per second update rate on a sport watch could permit the compass circuit to remain off to nearly 99 percent
of the life of the watch, with just 10 millisecond measurement snapshots per second and a one per minute set pulses
for perming correction. The HMC1052 and HMC1051Z sensors have a 5 MHz bandwidth in magnetic field sensing, so
the minimum snapshot measurement time is derived principally by the settling time of the op-amps plus the sampleand-hold time of the microcontroller’s ADCs.
In some “gaming” applications in wireless phones and PDAs, more frequent heading updates permits virtual reality
sensor inputs for software reaction. Typically these update rates follow the precedent set more than a century ago by
the motion picture industry (“Movies”) at 20 updates or more per second. While there is still some value in creating off
periods in between these frequent updates, some users may choose to only switch power on the sensor bridges
exclusively and optimize the remainder of the circuitry for low power consumption.
Compass Firmware Development
To implement an electronic compass with tilt compensation, the microcontroller firmware must be developed to gather
the sensor inputs and to interpret them into meaningful data to the end user system. Typically the firmware can be
broken into logical routines such as initialization, sensor output collection and raw data manipulation, heading
computation, calibration routines, and output formatting.
For the sensor output data collection, the analog voltages at microcontroller inputs AN0 through AN3 are digitized and
a “count” number representing the measured voltage is the result. For compassing, the absolute meaning of the ADC
counts scaled back to the sensor’s milli-gauss measurement is not necessary, however it is important to reference the
zero-gauss ADC count level. For example, an 8-bit ADC has 512 counts (0 to 511 binary), then count 255 would be
the zero offset and zero-gauss value.
In reality errors will creep in due to the tolerances of the sensor bridge (bridge offset voltage), multiplied by the
amplifier gain stages plus any offset errors the amplifiers contribute; and magnetic errors from hard iron effects
(nearby magnetized materials). Usually a factory or user calibration routine in a clean magnetic environment will
obtain a correction value of counts from mid ADC scale. Further tweaking of the correction value for each magnetic
sensor axis once the compass assembly is in its final user location, is highly desired to remove the magnetic
environment offsets.
For example, the result of measuring AN0 (Vref) is about count 255, and the measuring of AN1, AN2, and AN3 results
in 331, 262, and 205 counts respectively. Next calibration values of 31, -5, and 20 counts would be subtracted to
result in corrected values of 301, 267, and 205 respectively. If the pitch and roll were known to be zero; then the AN3
(Z-axis output) value could be ignored and the tilt corrected X and Y-axis values would be the corrected values of AN1
and AN2 minus the voltage reference value of AN0. Doing the math yields arctan [y/x] or arctan [(267-255)/(301-255)]
or 14.6 degrees east of magnetic north.
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HMC1055
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Heading Computation
SENSOR PRODUCTS
Once the magnetic sensor axis outputs are gathered and the calibration corrections subtracted, the next step toward
heading computation is to gather the pitch and roll (tilt) data from the MEMSIC MXS3334UL accelerometer outputs.
The MXS3334UL in perfectly horizontal (zero tilt) condition produces a 100Hz, 50 percent duty cycle Pulse Width
Modulated (PWM) digital waveform from its Doutx and Douty pins corresponding to the X and Y sensitive axis. These
output pins will change their duty cycle from 30% to 70% when tilted fully in each axis (±1g). The scaling of the PWM
outputs is strictly gravitational, so that a 45 degree tilt results in 707 milli-g’s or a slew of ±14.1% from the 50% center
point duty cycle.
With the MXS3334UL’s positive X-axis direction oriented towards the front of the user’s platform, a pitch downward
will result in a reduced PWM duty cycle, with a pitch upward increasing in duty cycle. Likewise, the Y-axis arrow is 90
degrees counter-clockwise which results in a roll left corresponding to a decreasing duty cycle, and roll right to an
increasing duty cycle.
Measuring the pitch and roll data for a microcontroller is reasonably simple in that the Doutx and Douty logic signals
can be sent to microcontroller digital input pins for duty cycle measurement. At firmware development or factory
calibration, the total microcontroller clock cycles between Doutx or Douty rising edges should be accrued using an
interrupt or watchdog timer feature to scale the 100Hz (10 millisecond) edges. Then measuring the Doutx and Douty
falling edges from the rising edge (duty cycle computation) should be a process of clock cycle counting. For example,
a 1MHz clocked microcontroller should count about 10,000 cycles per rising edge, and 5,000 cycle counts from rising
to falling edge would represent a 50% duty cycle or zero degree pitch or roll.
Once the duty cycle is measured for each axis output and mathematically converted to a gravitational value, these
values can be compared to a memory mapped table, if the user desires the true pitch and roll angles. For example, if
the pitch and roll data is to be known in one degree increments, a 91-point map can be created to match up
gravitational values (sign independent) with corresponding degree indications. Because tilt-compensated compassing
requires sine and cosine of the pitch and roll angles, the gravitational data is already formatted between zero and one
and does not require further memory maps of trigonometric functions. The gravity angles for pitch and roll already fit
the sine of the angles, and the cosines are just one minus the sine values (cosine = 1 – sine).
The equations:
X’ = X * cos(I) + Y * sin(T) * sin(I) – Z * cos(T) * sin(I)
Y’ = Y * cos(T) + Z * sin(T)
Create tilt compensated X and Y magnetic vectors (X’, Y’) from the raw X, Y, and Y magnetic sensor inputs plus the
pitch (I) and roll (T) angles. Once X’ and Y’ are computed, the compass heading can be computed by equation:
Azimuth (Heading) = arctan (Y’ / X’)
To perform the arc-tangent trigonometric function, a memory map needs to be implemented. Thankfully the pattern
repeats in each 90° quadrant, so with a one-degree compass resolution requirement, 90 mapped quotients of the arctangent function can be used. If 0.1° resolution is needed then 900 locations are needed and only 180 locations with
0.5° resolution. Also, special case quotient detections are needed for the zero and inifinity situations at 0°, 90, 180°,
and 270° prior to the quotient computation.
After the heading is computed, two heading correction factors may be added to handle declination angle and platform
angle error. Declination angle is the difference between the magnetic north pole and the geometric north pole, and
varies depending on the latitude and longitude (global location) of the user compass platform. If you have access to
Global Positioning Satellite (GPS) information resulting in a latitude and longitude computation, then the declination
angle can be computed or memory mapped for heading correction. Platform angle error may occur if the sensors are
not aligned perfectly with the mechanical characteristics of the user platform. These angular errors can be inserted in
firmware development and or in factory calibration.
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HMC1055
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COMPASS CALIBRATION
SENSOR PRODUCTS
In the paragraphs describing raw magnetic sensor data, the count values of X, Y, and Z are found from inputs AN0 to
AN3. A firmware calibration routine will create Xoff, Yoff and Xsf, and Ysf for calibration factors for “hard-iron”
distortions of the earth’s magnetic field at the sensors. Typically these distortions come from nearby magnetized
components. Soft-iron distortions are more complex to factor out of heading values and are generally left out for low
cost compassing applications. Soft-iron distortion arises from magnetic fields bent by un-magnetized ferrous materials
either very close to the sensors or large in size. Locating the compass away from ferrous materials provides the best
error reduction. The amount of benefit is dependant on the amount of ferrous material and its proximity to the
compass platform.
To derive the calibration factors, the sensor assembly (platform) and its affixed end-platform (e.g. watch/human, boat,
auto, etc.) are turned at least one complete rotation as the compass electronics collects many continuous readings.
The speed and rate of turn are based on how quickly the microcontroller can collect and process X, Y, and Z data
during the calibration routine. A good rule of thumb is to collect readings every few degrees by either asking the user
to make a couple rotations or by keeping in the rotation(s) slow enough to collect readings of the correct rate of turn.
The Xh and Yh readings during calibration are done with Xoff and Yoff at zero values, and axis scale factors (Xsf and
Ysf) at unity values. The collected calibration X and Y values are then tabulated to find the min and max of both X and
Y. At the end of the calibration session, the Xmax, Ymax, Xmin, and Ymin values are converted to the following:
Xsf = 1 or (Ymax –Ymin) / (Xmax – Xmin) , whichever is greater
Ysf = 1 or (Xmax –Xmin) / (Ymax – Ymin) , whichever is greater
Xoff = [(Xmax – Xmin)/2 – Xmax] * Xsf
Yoff = [(Ymax –Ymin)/2 –Ymax] * Ysf
Z-axis data is generally not corrected if the end-platform can not turned upside-down. In portable or hand-held
applications, then the compass assembly can be tipped upside down and Zoff can be computed like Xoff and Yoff, but
with only two reference points (upright and upside down). Factory values for Zoff maybe the only values possible.
Creating corrected X, Y, and Z count values are done as previously mentioned by subtracting the offsets. The scale
factor values are used only after the Vref counts are subtracted form the offset corrected axis counts. For more details
on calibration for iron effects, see the white paper “Applications of Magnetoresistive Sensors in Navigation Systems”
located on the magneticsensors.com website.
Offsets due to sensor bridge offset voltage of each sensor axis are part of the Xoff, Yoff, and Zoff computation. These
offsets are present even with no magnetic field disturbances. To find their true values, the set and reset drive circuits
can be toggled while taking measurements shortly after each transition. After a reset pulse, the magnetic field portion
of the sensor bridge will have flipped polarity while the offset remains the same. Thus two measurements, after a
reset and a set pulse can be summed together. The magnetic portions of the sum will cancel, leaving just a double
value of the offset. The result can then be divide by two to derive the bridge offset.
The reason for knowing the bridge offset, is that the offset will drift with temperature. Should the user desire the best
accuracy in heading, a new calibration should be performed with each encounter with a new temperature
environment. See application notes AN-212, AN-213, and AN-214 for further compass design considerations.
Ordering Information
Ordering Number
HMC1055
Product
3-Axis Compass Sensor Set
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
900302 12-02 Rev –
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SENSOR PRODUCTS
APPLICATIONS
Linear Displacement
Angular Displacement
Linear / Angular / Rotary
Displacement Sensors
HMC1501 / HMC1512
Motor Control
H
Valve Position
Proximity Detection
Current Spike Detection
Not actual size
igh resolution, low power MR sensor
capable of measuring the angle
direction of a magnetic field from a
magnet with <0.07° resolution.
Advantages of measuring field
direction versus field strength include:
insensitivity to the tempco of the
magnet, less sensitivity to shock and
vibration, and the ability to withstand
large variations in the gap between
the sensor and magnet. These
sensors may be operated on 3 volts
with bandwidth response of 0-5 MHz.
Output is typical Wheatstone bridge.
FEATURES AND BENEFITS
No Rare Earth Magnets
Unlike Hall effect devices which may require samarium cobalt or similar “rare earth”
magnets, the HMC1501 and HMC1512 can function with Alnico or ceramic type magnets.
Wide Angular Range
HMC1501—Angular range of ±45° with <0.07° resolution.
HMC1512—Angular range of ±90° with <0.05° resolution.
Effective Linear Range
Linear range of 8mm with two sensors mounted on two ends; range may be increased
through multiple sensor arrays operating together.
Absolute Sensing
Unlike incremental “encoding” devices, sensors know the exact position and require no
indexing for proper positional output.
Non-Contact Sensing
No moving parts to wear out; no dropped signals from worn tracks as in conventional
contact based rotary sensors.
Small Package
Available in an 8-pin surface mount package with case dimensions (exclusive of pins), of
5mm x 4mm x 1.2mm total mounting envelope, with pins of less than 6mm square.
Large Signal Output
Full Scale output range of 120mV with 5V of power supply.
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HMC1501 / HMC1512
SENSOR PRODUCTS
PRINCIPLES OF OPERATION
Anisotropic magnetoresistance (AMR) occurs in ferrous
materials. It is a change in resistance when a magnetic
field is applied in a thin strip of ferrous material. The magnetoresistance is a function of cos2θ where θ is the angle
between magnetization M and current flow in the thin strip.
When an applied magnetic field is larger than 80 Oe, the
magnetization aligns in the same direction of the applied
field; this is called saturation mode. In this mode, θ is the
angle between the direction of applied field and the current
flow; the MR sensor is only sensitive to the direction of
applied field.
Metal Contact
Current
Flow
M
θ
Permalloy
Thin Film
(NiFe)
Applied
Field
Applied Field Direction
M
M
The sensor is in the form of a Wheatstone bridge (Figure 1).
The resistance R of all four resistors is the same. The bridge
power supply VS causes current to flow through the resistors,
the direction as indicated in the figure for each resistor.
R+∆R
R-∆R
∆V
Both HMC1501 and HMC1512 are designed to be used in
saturation mode. HMC1501 contains one MR bridge and
HMC1512 has two identical MR bridges, coexisting on a
single die. Bridge B physically rotates 45° from bridge A.
The HMC1501 has sensor output ∆V=-VSS sin (2θ) and
the HMC1512 has sensor output ∆V=VSS sin (2θ) for sensor A and sensor B output ∆VS=-VSS cos (2θ), where VS is
supply voltage, S is a constant, determined by materials.
For Honeywell sensors, S is typically 12mV/V.
I
Vs
+M
M
R+∆R
R-∆R
Figure 1
PINOUT DRAWINGS
HMC1512
HMC1501
•
OUT+ 1
GND 1 2
3
4
θ
OUT- A
OUT- B
VBRIDGEB
VBRIDGEA
8 OUT7 GND 2
6
5 VBRIDGE
•
1
2
3
4
8
7
6
5
θ
GNDA
GNDB
OUT+ B
OUT+ A
Caution: Do not connect GND or Power to Pin 3,4 &6.
MR SENSOR CIRCUITS
VBRIDGE A
VBRIDGE
OUT +B
VBRIDGE B
R
R
R
R
R
R
OUT+
OUT-
R
GND 1
OUT+
A
OUTA
Bridge A
R
R
GND 2
GND A
R
Bridge B
R
R
GND B
OUT -B
2
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HMC1501 / HMC1512
SENSOR PRODUCTS
TYPICAL SENSOR OUTPUT
60
40
20
0
-20 0
-40
-60
-80
-100
HMC1512 output voltage vs. magnetic field angle
100
100
200
300
Sensor Output (mV)
Sensor Output (mV)
HMC1501 output voltage vs. magnetic field angle
400
50
0
0
100
200
300
-100
Theta (degree)
Bridge A
Bridge BB
Theta (degree)
A
APPLICATION CONFIGURATION
Linear Position
Moving Direction
Proximity Position
N
S
Moving Direction
400
-50
θ
Valve
Actuator
Stem
N
Reference
Direction
~0.5 to -1.5 inches
Rotary Position
HMC1501/1512 MR Sensor
Magnet
Magnet
S
N
N
S
N
Rotating Shaft
S
Rotating Shaft
PACKAGE DRAWING 8-Pin SOIC
D
A1
Symbol
A
A1
B
D
E
e
H
h
A
H
E
1
•
e
B
h x 45°
Millimeters
Inches
Min
Max
1.371
1.728
0.101
0.249
0.355
0.483
4.800
4.979
3.810
3.988
1.270 ref
5.816
6.198
0.381
0.762
Max
Min
.068
.054
.010
.004
.019
.014
.196
.189
.157
.150
.050 ref
.244
.229
.030
.015
3
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HMC1501 / HMC1512
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions*
Min
Bridge supply
HMC1512
Typ
Max
Units
1
5
25
1
5
25
V
Bridge current—1 mA
4
5
6.5
2.0
2.1
2.8
KΩ
> Saturation field
-45
+45
-90
+90
deg
Angle range
Vbridge = 5V, field 80 Oe,
(1) @ zero crossing
(2) @ Zero crossing, averaged
in the range of 45°
Peak -to-peak Voltage
Vbridge = 5V, field = 80 Oe
Bridge offset
Field 80 Oe, θ =0°
Saturation field
Min
Vbridge referenced to GND
Bridge resistance
Sensitivity
HMC1501
Typ
Max
Bridge A
Bridge B
2.1
1.8
2.1
1.8
mV/°
100
120
140
100
120
140
mV
-7
3
7
0
-4
2. 5
0
5
1
mV/V
Repeatability <0.03% FS
80
Bandwidth
Magnetic signal
0
Resolution
Bandwidth =10Hz,Vbridge =5V
0.07
0.05
°
Hysteresis error
Magnetic field >saturation field,
Vbridge = 5V
30
1.7x10-2
30
1.7x10-2
µV
deg
Bridge Ω tempco
TA = -40° C to +125° C
0.28
0.28
%/° C
Sensitivity tempco
TA = -40° C to +125° C
Vbridge = 5V
-0.32
-0.32
%/° C
Bridge offset tempco
TA = -40° C to +125° C
-0.01
-0.01
%/° C, FS
Noise at 1Hz, Vbridge = 5V
10 0
70
nV Hz
Vbridge = 5V
5
23
mW
Noise Density
Power Consumption
*Tested at 25°C except stated otherwise.
Where
5
G
0
5
MHz
Offset tempco Co = Vo (t) - Vo (o) = -0.01%/°C
VP-P*t
Where
Vo (o) = bridge offset at zero temperature
VP-P = peak-to-peak voltage
t = temperature in the range -40°C to 125°C
Vo (t) = offset at temperature t
Sensitivity tempco Cs = St-So = -0.32%/°C
So*t
Where
So = sensitivity at zero temperature
t = temperature in the range -40°C to 125°C
St = sensitivity at temperature t
Power consumption P =
80
V2
R
1 KA/m = 12.5 Gauss
1 Tesla = 104 Gauss
V = Bridge supply voltage
R = Bridge resistance
Honeywell reserves the right to make changes to any products or technology herein to improve reliability, function or design. Honeywell does not assume any liability
arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Solid State Electronics Center
12001 State Highway 55
Plymouth, MN 55441
1-800-323-8295
http://www.ssec.honeywell.com
900246
8-00 Rev. B
4
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HMC2003
SENSOR PRODUCTS
THREE-AXIS MAGNETIC SENSOR HYBRID
Features
•
•
•
•
•
•
•
•
•
20-pin Wide DIP Footprint (1” by 0.75”)
Precision 3-axis Capability
Factory Calibrated Analog Outputs
40 micro-gauss to ±2 gauss Dynamic Range
Analog Output at 1 Volt/gauss (2.5V @ 0 gauss)
Onboard +2.5 Volt Reference
+6 to +15 Volt DC Single Supply Operation
Very Low Magnetic Material Content
-40° to 85°C Operating Temperature Range
General Description
The Honeywell HMC2003 is a high sensitivity, threeaxis magnetic sensor hybrid assembly used to measure
low magnetic field strengths. Honeywell’s most
sensitive magneto-resistive sensors (HMC1001 and
HMC1002) are utilized to provide the reliability and
precision of this magnetometer design. The HMC2003
interface is all analog with critical nodes brought out to
the pin interfaces for maximum user flexibility. The
internal excitation current source and selected gain and
offset resistors, reduces temperature errors plus gain
and
offset
drift.
Three
precision
low-noise
instrumentation amplifiers with 1kHz low pass filters
provide accurate measurements while rejecting
unwanted noise.
APPLICATIONS
• Precision Compassing
BLOCK DIAGRAM
• Navigation Systems
• Attitude Reference
• Traffic Detection
• Proximity Detection
• Medical Devices
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HMC2003
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions(1)
Min
Typ
Max
Units(2)
Sensitivity
0.98
1
1.02
V/gauss
Null Field Output
2.3
2.5
2.7
V
Magnetic Field
Resolution
µgauss
40
Field Range
Maximum Magnetic Flux Density
-2
2
Output Voltage
Each Magnetometer Axis Output
0.5
4.5
Bandwidth
1
gauss
kHz
Errors
±1 gauss Applied Field Sweep
0.5
2
±2 gauss Applied Field Sweep
1
2
Hysteresis Error
3 Sweeps across ±2 gauss
0.05
0.1
%FS
Repeatability Error
3 Sweeps across ±2 gauss
0.05
0.1
%FS
0.1
%FS
10.5
ohms
48.5
mA/gauss
200
mA
4.5
6
ohms
3.2
5
amps
Linearity Error
Power Supply Effect
PS Varied from 6 to 15V
%FS
With ±1 gauss Applied Field Sweep
Offset Strap
Resistance
Sensitivity
46.5
47.5
Current
Set/Reset Strap
Resistance
Current
2msec pulse, 1% duty cycle
3.0
Tempcos
Field Sensitivity
Null Field
-600
ppm/°C
Set/Reset Not Used
±400
ppm/°C
Set/Reset Used
±100
Environments
Temperature
Operating
-40
-
+85
°C
Storage
-55
-
+125
°C
Shock
100
g
Vibration
2.2
g rms
Electrical
Supply Voltage(3)
6
15
VDC
Supply Current
20
mA
(1) Unless otherwise stated, test conditions are as follows: Power Supply = 12VDC, Ambient Temp = 25°C,
Set/Reset switching is active
(2) Units: 1 gauss = 1 Oersted (in air) = 79.58 A/m = 10E5 gamma
(3) Transient protection circuitry should be added across V+ and Gnd if an unregulated power supply is used.
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HMC2003
SENSOR PRODUCTS
General Description
Honeywell’s three axis magnetic sensor hybrid uses three permalloy magneto-resistive sensors and custom interface
electronics to measure the strength and direction of an incident magnetic field. These sensors are sensitive to
magnetic fields along the length, width, and height (X, Y, Z axis) of the 20-pin dual-in-line hybrid. Fields can be
detected less than 40 microgauss and up to ±2 gauss. Analog outputs are available for each X, Y and Z axis from the
hybrid. With the sensitivity and linearity of this hybrid, changes can be detected in the earth’s magnetic field to
provide compass headings or attitude sensing. The high bandwidth of this hybrid allows for anomaly detection of
vehicles, planes, and other ferrous objects at high speeds.
The hybrid is packaged on a small printed circuit board (1” by 0.75”) and has an on-chip +2.5 voltage reference that
operates from a single 6 to 15V supply. The hybrid is ideal for applications that require two- or three-axis magnetic
sensing and have size constraints and need a magnetic transducer (magnetometer) front-end. Note that the hybrid’s
resistor values will vary, or an abscense of some resistor components, is likely due to individual factory calibration.
Integrated with the sensor elements composed of wheatstone bridge circuits, are magnetically coupled straps that
replace the need for external field coils and provide various modes of operation. The Honeywell patented integrated
field offset straps (Xoff+ and Xoff-, etc.) can be used electrically to apply local magnetic fields to the bridges to buck,
or offset an applied incident field. This technique can be used to cancel unwanted ambient magnetic fields (e.g. hardiron magnetism) or in a closed loop field nulling measurement circuit. The offset straps nominally provide 1 gauss
fields along the sensitive axis per 48mA of offset current through each strap.
The HMC2003’s magnetic sensors can be affected by high momentary magnetic fields that may lead to output signal
degradation. In order to eliminate this effect, and maximize the signal output, a magnetic switching technique can be
applied to the bridge using set/reset pins (SR+ and SR-) that eliminates the effect of past magnetic history. Refer to
the application notes that provide information on set/reset circuits and operation.
Pinout Diagram and Package Drawing
Symbol
A
A1
D
e
H
Millimeters
Min
Max
10.92 11.94
2.92
3.42
25.91 27.30
2.41
2.67
18.03 19.69
Inches
Min
Max
0.43
0.47
0.115
0.135
1.02
1.075
0.095
0.105
0.71
0.775
Ordering Information
Ordering Number
HMC2003
Product
Three-Axis Magnetic Sensor Hybrid
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HMC2003
SENSOR PRODUCTS
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
900151 02-04 Rev. E
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HMC6352
SENSOR PRODUCTS
DIGITAL COMPASS SOLUTION
Features
•
•
•
•
•
•
•
Fully Integrated Compass Module
2-Axis Magnetic Sensors with Electronics
Miniature (6.5 by 6.5 by 1.5mm) 24-Pin LCC
Package
2.7 to 5.2 volt Supply Range
Accurate Compassing Capability
I2C Digital Interface
User Selectable Slave Address
Product Description
The Honeywell HMC6352 2-Axis Digital Integrated
Compass Solution combines a two-axis MR magnetic
field sensor design with the required analog and digital
support circuits for heading computation.
By combining the sensor elements and all the
processing electronics into a 6.5mm square LCC
package, designers will have the simplest solution to
integrate low cost and space efficient electronic
compasses for wireless phones, consumer electronics,
vehicle compassing, and antenna positioning.
BOTTOM VIEW
DIAGRAMS
PINOUT
BLOCK DIAGRAM
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HMC6352
SENSOR PRODUCTS
HMC6352 SPECIFICATIONS
Characteristics
Conditions (1)
Min
Typ
Max
Units
Supply Voltage
Vsupply to GND
2.7
3.0
5.2
Volts
Supply Current
Vsupply to GND
Steady State (Vsupply = 3.0V)
1
mA
Steady State (Vsupply = 5.0V)
2
mA
Dynamic Peaks
Field Range
(2)
Heading Accuracy
Total applied field
0.10
mA
0.75
gauss
6
degRMS
Heading Resolution
0.5
deg
Heading
Repeatability
1.0
deg
Disturbing Field
HMC6352
-
10
Sensitivity starts to degrade.
20
gauss
Enable set/reset function to restore sensitivity.
Max. Exposed
Field
Operating
No permanent damage and set/reset function
restores performance.
10000
gauss
Ambient
-20
70
°C
Ambient
-55
125
°C
225
°C
Temperature
Storage
Temperature
Reflow
Per JEDEC J-STD-020B
Temperature
Output
Size
Heading, Mag X, Mag Y
6.5 x 6.5 x 1.5
Weight
0.14
(1) Tested at 25°C except stated otherwise.
(2) Field upper limit can be extended by using external resistors across CA1/CA2 and CB1/CB2.
mm
grams
Pin Configuration/Package Dimensions
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HMC6352
SENSOR PRODUCTS
Pin Descriptions
HMC6352
Pin
Name
1
OF2
SR+
3
NC
4
NC
5
GND
6
NC
7
SDI
8
SDO
9
PGM
10
SCL
11
SS
12
NC
13
NC
14
VDD
15
NC
16
NC
17
NC
18
NC
19
CB2
20
CB1
21
NC
22
CA2
23
CA1
24
OF+
Description
No User Connection (Offset Strap Negative)
No User Connection (Set/Reset Strap Positive)
No User Connection
No User Connection
Supply/System Ground
No User Connection
I2C Data Output (SPI Data In)
No User Connection (SPI Data Out)
No User Connection (Program Enable)
I2C Clock (SPI Clock)
No User Connection (Slave Select)
No User Connection
No User Connection
Supply Voltage Positive Input (+2.7VDC to +5.0VDC)
No User Connection
No User Connection
No User Connection
No User Connection
Amplifier B Filter Capacitor Connection
Amplifier B Filter Capacitor Connection
No User Connection
Amplifier A Filter Capacitor Connection
Amplifier A Filter Capacitor Connection
No User Connection (Offset Strap Positive)
I2C Communication Protocol
The HMC6352 communicates via a two-wire I2C bus system as a slave device. The HMC6352 uses a layered
protocol with the interface protocol defined by the I2C bus specification, and the lower command protocol defined by
Honeywell. The data rate is the standard-mode 100kbps rate as defined in the I2C Bus Specification 2.1. The bus bit
format is an 8-bit Data/Address send and a 1-bit acknowledge bit. The format of the data bytes (payload) shall be
case sensitive ASCII characters or binary data to the HMC6352 slave, and binary data returned. Negative binary
values will be in two’s complement form. The default (factory) HMC6352 7-bit slave address is 42(hex) for write
operations, or 43(hex) for read operations.
The HMC6352 Serial Clock (SCL) and Serial Data (SDA) lines do not have internal pull-up resistors, and require
resistive pull-ups (Rp) between the master device (usually a host microprocessor) and the HMC6352. Pull-up
resistance values of about 10k ohms are recommended with a nominal 3.0-volt supply voltage. Other values may be
used as defined in the I2C Bus Specification 2.1.
The SCL and SDA lines in this bus specification can be connected to a host of devices. The bus can be a single
master to multiple slaves, or it can be a multiple master configuration. All data transfers are initiated by the master
device which is responsible for generating the clock signal, and the data transfers are 8 bit long. All devices are
addressed by I2C’s unique 7 bit address. After each 8-bit transfer, the master device generates a 9 th clock pulse, and
releases the SDA line. The receiving device (addressed slave) will pull the SDA line low to acknowledge (ACK) the
successful transfer or leave the SDA high to negative acknowledge (NACK).
Per the I2C spec, all transitions in the SDA line must occur when SCL is low. This requirement leads to two unique
conditions on the bus associated with the SDA transitions when SCL is high. Master device pulling the SDA line low
while the SCL line is high indicates the Start (S) condition, and the Stop (P) condition is when the SDA line is pulled
high while the SCL line is high. The I2C protocol also allows for the Restart condition in which the master device
issues a second start condition without issuing a stop.
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HMC6352
SENSOR PRODUCTS
All bus transactions begin with the master device issuing the start sequence followed by the slave address byte. The
address byte contains the slave address; the upper 7 bits (bits7-1), and the Least Significant bit (LSb). The LSb of the
address byte designates if the operation is a read (LSb=1) or a write (LSb=0). At the 9 th clock pulse, the recieving
slave device will issue the ACK (or NACK). Following these bus events, the master will send data bytes for a write
operation, or the slave will transmit back data for a read operation. All bus transactions are terminated with the master
issuing a stop sequence.
The following timing diagram shows an example of a master commanding a HMC6352 (slave) into sleep mode by
sending the “S” command. The bottom two traces show which device is pulling the SDA line low.
START
0
1
0
0
0
0
1
0
ACK
0
1
0
1
0
0
1
1
ACK
STOP
SDA
SCL
M_SDA
S_SDA
42(hex)
Write to This I2C Address
“S”
Command
I2C bus control can be implemented with either hardware logic or in software. Typical hardware designs will release
the SDA and SCL lines as appropriate to allow the slave device to manipulate these lines. In a software
implementation, care must be taken to perform these tasks in code.
Command Protocol
The command protocol defines the content of the data (payload) bytes of I2C protocol sent by the master, and the
slave device (HMC6352).
After the master device sends the 7-bit slave address, the 1-bit Read/Write, and gets the 1-bit slave device
acknowledge bit returned; the next one to three sent data bytes are defined as the input command and argument
bytes. To conserve data traffic, all response data (Reads) will be context sensitive to the last command (Write) sent.
All write commands shall have the address byte least significant bit cleared (factory default 42(hex)). These
commands then follow with the ASCII command byte and command specific binary formatted argument bytes in the
general form of:
(Command ASCII Byte) (Argument Binary MS Byte) (Argument Binary LS Byte)
The slave (HMC6352) shall provide the acknowledge bits between each data byte per the I2C protocol. Response
byte reads are done by sending the address byte (factory default 43(hex)) with the least significant bit set, and then
clocking back one or two response bytes, last command dependant. For example, an “A” command prompts the
HMC6352 to make a sensor measurement and to route all reads for a two byte compass heading or magnetometer
data response. Then all successive reads shall clock out two response bytes after sending the slave address byte.
Table 1 shows the HMC6352 command and response data flow.
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HMC6352
SENSOR PRODUCTS
Table 1 – HMC6352 Interface Commands/Responses
Command
Byte
ASCII (hex)
w (77)
r (72)
G (47)
g (67)
Argument 1
Byte
(Binary)
EEPROM
Address
EEPROM
Address
RAM
Address
RAM
Address
S (53)
W (57)
O (4F)
C (43)
E (45)
L (4C)
A (41)
Argument 2
Byte
(Binary)
Data
Response 1
Byte
(Binary)
Response 2
Byte
(Binary)
Data
Description
Write to EEPROM
Read from EEPROM
Data
Write to RAM Register
Data
MSB Data
Read from RAM Register
LSB Data
Enter Sleep Mode (Sleep)
Exit Sleep Mode (Wakeup)
Update Bridge Offsets (S/R Now)
Enter User Calibration Mode
Exit User Calibration Mode
Save Op Mode to EEPROM
Get Data. Compensate and
Calculate New Heading
Operational Controls
HMC6352 has two parameters; Operational Mode and Output Mode, which control its operation. The Operational
Mode control byte is located at RAM register byte 74(hex) and is shadowed in EEPROM location 08(hex). This byte
can be used to control the continuous measurement rate, set/reset function, and to command the HMC6352 into the
three allowed operating modes; Standby, Query, and Continuous.
The Output Mode control byte is located at RAM register byte 4E(hex) and is not shadowed in the EEPROM, and
upon power up the device is in the Heading output mode. This byte can be changed to get magnetometer data if
necessary but is typically left in a default heading data mode.
Non-Volatile Memory
The HMC6352 contains non-volatile memory capability in the form of EEPROM that retains key operational
parameters and settings for electronic compassing. Table 2 shows the balance of the EEPROM locations that the
user can read and write to. Details on the features of these location bytes will be discussed in the following
paragraphs.
Table 2 – HMC6352 EEPROM Contents
EE Address (hex)
00
01
02
03
04
05
06
07
08
Byte Description
I2C Slave Address
Magnetometer X Offset MSB
Magnetometer X Offset LSB
Magnetometer Y Offset MSB
Magnetometer Y Offset LSB
Time Delay (0 – 255 ms)
Number of Summed measurements(1-16)
Software Version Number
Operation Mode Byte
Factory Default
42(hex)
factory test value
factory test value
factory test value
factory test value
01(hex)
04(hex)
> 01(hex)
50(hex)
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HMC6352
SENSOR PRODUCTS
Operational Modes
The HMC6352 has three operational modes plus the ability to enter/exit the non-operational (sleep) mode by
command. Sleep mode sends the internal microprocessor into clock shutdown to save power, and can be brought
back by the “W” command (wake). The “S” command returns the processor to sleep mode. The three operational
modes are defined by two bits in the internal HMC6352 Operation Mode register. If the master device sends the “L”
command, the current operational mode control byte in the RAM register is loaded into the internal EEPROM register
and becomes the default operational mode on the next power-up. The application environment of the HMC6352 will
dictate the most suitable operational mode.
Standby Mode: (Operational Mode=0) This is the factory default mode. The HMC6352 waits for master device
commands or change in operational mode. Receiving an “A” command (get data) will make the HMC6352 perform a
measurement of sensors (magnetometers), compute the compensated magnetometer and heading data, and wait for
the next read or command. No new measurements are done until another “A” command is sent. This mode is useful
to get data on demand or at random intervals as long as the application can withstand the time delay in getting the
data.
Query Mode: (Operational Mode=1) In this mode the internal processor waits for “A” commands (get data), makes
the measurements and computations, and waits for the next read command to output the data. After each read
command, the HMC6352 automatically performs another get data routine and updates the data registers. This mode
is designed to get data on demand without repeating “A” commands, and with the master device controlling the timing
and data throughput. The tradeoff in this mode is the previous query latency for the advantage of an immediate read
of data.
The above two modes are the most power conserving readout modes.
Continuous Mode: (Operational Mode=2) The HMC6352 performs continuous sensor measurements and data
computations at selectable rates of 1Hz, 5Hz, 10Hz, or 20Hz, and updates the output data bytes. Subsequent “A”
commands are un-necessary unless re-synchronization to the command is desired. Data reads automatically get the
most recent updates. This mode is useful for data demanding applications.
The continuous mode measurement rate is selected by two bits in the operational mode selection byte, along with the
mode selection and the periodic Set/Reset bit. The periodic Set/Reset function performs a re-alignment of the sensors
magnetic domains in case of sensor perming (magnetic upset event), operating temperature shifts, and normal
thermal agitation of the domains. Exposure of the HMC6352 to magnetic fields above 20 gauss (disturbing field
threshold) leads to possible measurement inaccuracy or “stuck” sensor readings until the set/reset function is
performed. With the periodic Set/Reset bit set, the set/reset function occurs every few minutes.
Operational Mode Control Byte Syntax
As described above, the HMC6352 operation mode, measurement rate, and periodic set/reset are selected and
stored both in a processor RAM register and in EEPROM. Upon power-up the EEPROM will transfer the saved
operational mode control byte into register address 74(hex). The following is the byte format:
Bit 7 =0
Bits 6 and 5 (Continuous Mode Measurement Rate)
Bit 6
0
0
1
1
Bit 5
0
1
0
1
Description
1 Hz Measurement Rate
5 Hz Measurement Rate
10 Hz Measurement Rate
20 Hz Measurement Rate
Bit 4 (Periodic Set/Reset), 0 = Off, 1 = On
Bit 3 = 0
Bit 2 = 0
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HMC6352
SENSOR PRODUCTS
Bits 1 and 0 (Operational Mode Value)
Bit 1
0
0
1
1
Bit 0
0
1
0
1
Description
Standby Mode
Query Mode
Continuous Mode
Not Allowed
The total bit format for the Operational Mode Byte is shown below:
Bit 7 (MSB)
0
Bit 6
M. Rate_H
Bit 5
M. Rate_L
Bit 4
Per. S/R
Bit 3
0
Bit 2
0
Bit 1
Op Mode_H
Bit 0 (LSB)
Op Mode_L
Output Data Modes
The read response bytes after an “A” command, will cause the HMC6352 will return two bytes with binary formatted
data. Either heading or magnetometer data can be retrieved depending on the output data selection byte value.
Negative signed magnetometer data will be returned in two’s complement form. This output data control byte is
located in RAM register location 4E(hex) and defaults to value zero (heading) at power up.
The following is the byte format:
Bits 7 through 3 = 0
Bits 0, 1, 2 (Output Mode Value)
Bit 2
0
0
0
0
1
Bit 1
0
0
1
1
0
Bit 0
0
1
0
1
0
Description
Heading Mode
Raw Magnetometer X Mode
Raw Magnetometer Y Mode
Magnetometer X Mode
Magnetometer Y Mode
The total bit format for the Output Mode Byte is shown below:
Bit 7 (MSB)
0
Bit 6
0
Bit 5
0
Bit 4
0
Bit 3
0
Bit 2
Mode
Bit 1
Mode
Bit 0 (LSB)
Mode
Heading Mode: The heading output data will be the value in tenths of degrees from zero to 3599 and provided in
binary format over the two bytes.
Raw Magnetometer Modes: These X and Y raw magnetometer data readings are the internal sensor values
measured at the output of amplifiers A and B respectively and are 10-bit 2’s complement binary ADC counts of the
analog voltages at pins CA1 and CB1. The leading 6-bits on the MSB are zero filled or complemented for negative
values. The zero count value will be about half of the supply voltage. If measurement averaging is implemented, the
most significant bits may contain values of the summed readings.
Magnetometer Modes: These X and Y magnetometer data readings are the raw magnetometer readings plus offset
and scaling factors applied. The data format is the same as the raw magnetometer data. These compensated data
values come from the calibration routine factors plus additional offset factors provided by the set/reset routine.
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HMC6352
SENSOR PRODUCTS
User Calibration
The HMC6352 provides a user calibration routine with the “C” command permitting entry into the calibration mode and
the “E” command to exit the calibration mode. Once in calibration mode, the user is requested to rotate the compass
on a flat surface at least one full circular rotation while the HMC6352 collects several readings per second at various
headings with the emphasis on rotation smoothness to gather uniformly spaced readings. Optimally two rotations over
20 seconds duration would provide an accurate calibration. The calibration time window is recommended to be from 6
seconds up to 3 minutes depending on the end user’s platform.
The calibration routine collects these readings to correct for hard-iron distortions of the earth’s magnetic field. These
hard-iron effects are due to magnetized materials nearby the HMC6352 part that in a fixed position with respect to the
end user platform. An example would be the magnetized chassis or engine block of a vehicle in which the compass is
mounted onto. Upon exiting the calibration mode, the resulting magnetometer offsets and scaling factors are updated
I2C Slave Address
The I2C slave address byte consists of the 7 most significant bits with the least siginificant bit zero filled. A described
earlier, the default (factory) value is 42(hex) and the legal I2C bounded values are between 10(hex) and F6(hex). This
slave address is written into EEPROM address 00(hex) and changed on the power up.
Magnetometer Offsets
The Magnetometer Offset bytes are the values stored after the completion of the last factory or user calibration
routine. Additional value changes are possible, but will be overwritten when the next calibration routine is completed.
Note that these offset values are added to the sensor offset values computed by the set/reset routine to convert the
raw magnetometer data to the compensated magnetometer data. These values are written into EEPROM addresses
01(hex) to 04 (hex) and loaded to RAM on the power up. These offsets are in ADC counts applied to the 10-bit ADC
raw magnetometer data. Most offset MSB values will likely be zero filled or complemented.
Time Delay
The EEPROM time delay byte is the binary value of the number of milliseconds from the time a measurement request
was commanded and the time the actual measurements are made. The default value is 01(hex) for no delay. Extra
measurement delays maybe desired to allow for amplifier stabilization from immediate HMC6352 power-up or for
external filter capacitor selection that limits the bandwidth and time response of the amplifier stages. This value is
written into EEPROM address 05(hex) and loaded to RAM on the power up.
Measurement Summing
This EEPROM summed measurement byte permits designers/users to back average or data smooth the output data
(heading, magnetometer values) to reduce the amount of jitter in the data presentation. The default value is 04(hex)
which is four measurements summed. A value of 00(hex) would be no summing. Up to 16 sets of magnetometer data
may be selected for averaging. This slave address is written into EEPROM address 06(hex) and loaded to RAM on
the power up.
Software Version
This EEPROM software version number byte contains the binary value of the programmed software. Values of
01(hex) and beyond are considered production software.
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HMC6352
SENSOR PRODUCTS
Timing Requirements
Table 3 contains the time delays required by HMC6352 upon receipt of the command to either perform the
commanded task or to have the response available on the I2C bus.
Table 3 – Interface Command Delays
Command
Byte
ASCII (hex)
w (77)
r (72)
G (47)
g (67)
S (53)
W (57)
O (4F)
C (43)
E (45)
L (4C)
A (41)
Description
Write to EEPROM
Read from EEPROM
Write to RAM Register
Read from RAM Register
Enter Sleep Mode (Sleep)
Exit Sleep Mode (Wakeup)
Update Bridge Offsets (S/R Now)
Enter User Calibration Mode
Exit User Calibration Mode
Save Op Mode to EEPROM
Get Data. Compensate and Calculate
New Heading
Time Delay (µsec)
70
70
70
70
10
100
6000
10
14000
125
6000
Command and Operation Mode Interactions
All commands are accepted in the standby mode. Honeywell strongly recommends using this mode during the initial
setup stage. Setting up of the HMC6352 operation mode and its slave address are typical set up examples. Although
execution of all commands in the Query and Continuous Modes is acceptable, the completion outcome is not
guaranteed.
Q: How to Read Data from HMC6352?
A:
In Standby Mode - Use “A” command.
In Query Mode - Send 43(hex) slave address to read data and clock out the two register data bytes for
heading. An initial “A” command is needed to update the heading after each read.
In Continuous Mode - Send 43(hex) slave address to read data and clock out the register data bytes for
heading. The “A” command is not allowed or required.
Waveform Examples
Example 1: This example shows how to read a single byte from the HMC6352. The Slave (HMC6352) continues to
hold the SDA line low after the acknowledge (ACK) bit because the first bit of the data byte is a zero. Remember that
the data read is last command sensitive.
SDA
SCL
M_SDA
S_SDA
43(hex)
Read From This I2C Address
55(hex)
Data
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HMC6352
SENSOR PRODUCTS
Example 2: This example shows how to read two bytes from the HMC6352 (slave). The slave continues to hold the
SDA line low after the acknowledge bit because the first bit of the data bytes is zero.
SDA
SCL
M_SDA
S_SDA
43(hex)
Read From This I2C Address
55(hex)
Data
00(hex)
Data
Example 3: This example shows how to command HMC6352 to read a RAM register by sending the “g” command
and the register address 7F(hex). Note that this example does not show the process of reading the answer. See
example 1 for reading a byte.
SDA
SCL
M_SDA
S_SDA
42(hex)
Write to This I2C Address
“g”
Command
7F(hex)
Register 7F
Example 4: This example shows how to write to a RAM register in the HMC6352 by sending the “G” command, the
register address 7F(hex), and the data byte 55(hex) to the HMC6352 slave.
SDA
SCL
M_SDA
S_SDA
42(hex)
Write to This I2C Address
“G”
Command
7F(hex)
Register 7F
55(hex)
Data
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HMC6352
SENSOR PRODUCTS
Example 5: The final example shows how to read RAM register 7F(hex). First perform a write operation to command
the HMC6352 to read a RAM register and define which register to read (Example 3). The sensor puts the answer in
the data buffer. Then perform a read operation to clock out the answer (Example 1). There is a Stop/Start event in
between the write operation and the read operation. This example is just a combination of Examples 3 and 1, but it is
provided to show that reading a register involves both a write and a read operation.
START
STOP
SDA
SCL
M_SDA
S_SDA
42(hex)
“g”
Write to This I2C Address Command
7F(hex)
Register 7F
43(hex)
Read From This
I2C Address
55(hex)
Data
Application Notes
The HMC6352 Integrated Compass Sensor circuit is composed of two magneto-resistive (MR) sensors with
orthogonal orientation for sensing the horizontal components of the earth’s magnetic field (0 to 630 milli-gauss), plus
two amplifiers, a set/reset drive circuit, and a microprocessor (µP). Best accuracy is obtained in clean magnetic
environments (free air) and held level, or perpendicular to the gravitational direction. At worst case, each degree of tilt
from a level orientation could add two degrees of compass heading error. Magnetic errors can be introduced if
operated near strong magnetic sources such as microphone or speaker magnets, transformers in test equipment, and
CRT deflection yokes in video displays/monitors. These magnetic errors can typically be reduced or eliminated by
performing the calibration routine.
When locating the HMC6352 in dense printed circuit board designs, take precautions in location of this magnetic field
sensing device for soft-iron effects that bend the earth’s magnetic field. These soft-iron effects are from ferrous
materials without residual magnetization and tend to be items like nickel-plating on SMT component contacts and
RFI/EMI shielding materials. The amount of stand-off of the HMC6352 from these soft-irons is heuristic and
dependant on the amount of material, material shape, and proximity.
A user calibration mode is available in the HMC6352 to diminish hard-iron effects of the end-user’s (customer’s)
location of the product. Hard-iron effects come from nearby ferrous materials with residual magnetism that buck or
boost the intensity of the earth’s magnetic field, leading to heading errors. Such hard-iron effects come from vehicle
chassis, speaker magnets, and high current conductors or circuit traces.
PCB Pad Definition
(Dimensions in Millimeters)
The HMC6352 is a fine pitch LCC package with a 0.80mm pin pitch (spacing), with the pin pads defined as 0.70mm
by 0.33mm in size. PCB pads are recommended to be oversized by 0.025mm from each pad for a short dimension
oversize of 0.05mm. The interior PCB pad is recommended to be 0.05mm oversized per pin with an exterior oversize
of 0.20mm for proper package centering and to permit test probing.
Soldering attachment shall be done by SMT reflow methods with preheating, soaking, reflow, and cooling profiles as
described in JEDEC J-STD-020B for large body parts. Both lead eutectic and lead-free profiles may be used. Caution,
excessive temperature exposure beyond the profiles may result in internal damage to the HMC6352 circuits.
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HMC6352
SENSOR PRODUCTS
24
1
TOP VIEW
5.00
6.90
0.80
0.38
MECHANICAL DIMENSIONS
(In millimeters)
D
A
E
e
E1
e
D1
Dimension
D
D1
E
E1
e
A
Minimum
1.37
Nominal
6.50 BSC
4.00 BSC
6.50 BSC
4.00 BSC
0.8 Basic
1.52
Maximum
1.67
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HMC6352
SENSOR PRODUCTS
SOLDERING GUIDELINES
The HMC6352 shall follow the guidelines set by JEDEC J-STD-020B for handling and solder reflow for this surface
mount device. It is recommended to follow the guidelines for Sn-Pb Eutectic, Large Body profile parts.
Most LCC packages have no special requirements beyond normal procedures for attaching SMT components to
printed circuit boards. The exception to this process is the Honeywell HMC6352 that has a FR4 substrate package
with epoxy top encapsulation. This package design use two solder types with differing reflow temperatures. Inside this
package, a high-temp reflow solder is used that reflows at 225°C and above to make internal circuit connections. On
the package outside, low-temp solder is recommended with a reflow temp range from 180 to 210°C.
Three heating zones are defined in SMT reflow soldering process; the preheating zone, the soaking zone, and the
reflow zone. The preheating zone includes the soaking zone, and nominally ranges from 2 to 4 minutes depending on
temperature rise to arrive in the 160°C to 180°C soaking plateau to active the flux and remove any remaining moisture
in the assembly. Preheat rise times must not exceed 3°C per second to avoid moisture and mechanical stresses that
result in “popcorning” the package encapsulation.
The soaking zone is a one to two minute temperature stabilization time to bring the all the PCB assembly to an even
temperature. Typically this zone has a 0.5 to 0.6°C rise in temperature heading towards the main reflow heating
elements. The reflow zone is 30 to 90 second bump in temperature over the 180°C point to reflow the screened solder
paste before a gradual cooling. The peak temperature is typically in the 210°C to 225°C range. In dual temp solder
parts, it is recommended that peak temperatures remain at least 5°C below the internal reflow solder temperature (i.e.
220°C). The figure below shows a typical reflow profile.
It should be noted that lead-free solders tend to require higher peak reflow temperatures and longer reflow times.
Cooling zone temperature fall should decrease not more than 6°C per second to avoid mechanical stresses in the
PCB assembly.
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HMC6352
SENSOR PRODUCTS
REFERENCE DESIGN
The schematic diagram in Figure 1 shows the basic HMC6352 application circuit with a minimum of external
components.
From Figure 1, the host microprocessor (µP) controls the HMC6352 via I2C serial data interface lines for data (SDA)
and clock (SCL). Two external 10k-ohm pull-up resistors to the nominal +3 volt DC supply create normally high logic
states when the interface lines are not in use. The host initiates use of the interface by creating the 100kHz clock and
pulling low the data line to indicate the start condition. The data line logic state transitions are only allowed during the
clock low states and require the data line to be stable in the high states, with the exception of the start and stop
conditions.
Figure 1
Reference Design Schematic
The 0.01µF supply decoupling capacitor in this reference can be omitted if another supply filter capacitor is already
included in the overall circuit design. If the supply traces extend beyond a couple inches to the HMC6352, it is
advisable to add a local supply decoupling capacitor near the HMC6352 to retain optimum circuit stability.
Additional masters and slaves can be added to the I2C bus traces without interface trouble to the HMC6352. There
are no periodic maintenance commands required, and even HMC6352 sleep mode or power shutdown can be
accomplished without harm to the data or clock lines.
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HMC6352
SENSOR PRODUCTS
Amplifier Filter Connections
The HMC6352 design has provisions for the feedback loop of each amplifier stage to be accessible via the CA1, CA2,
CB1, and CB2 pin contacts. Across the contacts and internal to the HMC6352 is the amplifier section plus a 1200kohm feedback resistance to set the voltage gain. By placing small value ceramic capacitors across CA1 to CA2 (or
CB1 to CB2), the designer can set the –3dB bandwidth of the amplified magnetometer signals to drop spurious
magnetic interference in the system. For example a 120 pico-Farad capacitor (Cext) in the amplifier feedback loop
would limit the bandwidth to about 1kHz. Be aware that larger values of capacitance begin to slow the amplifier
response to where the measurement delay time EEPROM byte may have to be increased in value to let the signal
settle before making a measurement. Figure 2 shows the partial schematic of the amplifier feedback loop.
Figure 2
Amplifier Filter Connections
An optional gain reducing resistor (Rext) could also place across the feedback loop of the amplifier stages. With the
amplifier set with the internal 1200 k-ohm feedback for ±750 milli-gauss maximum magnetic field flux density, a
second 1200k-ohm external resistor would halve the gain and permit ±1.5 gauss capability if desired. Gain can be
reduced for up to ±6 gauss capability for magnetometry-only applications or compassing with significant magnetic
stray fields nearby.
ORDERING INFORMATION
Ordering Number
HMC6352
Product
Digital Compass Solution, I2C
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
U.S. Patents 4,441,072 4,533,872 4,569,742 4,681,812 4,847,584 6,529,114 and patents pending apply to the
technology described herein.
900307 07-04 Rev A
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HMC6352 2-Axis Digital Compass Module
Device Operational Overview HMC6352
HMC6352 has two parameters; Operational Mode and Output Mode, which control its operation.
The Operational Mode is a RAM byte (0x74) and is shadowed in EEPROM location 0x08. This byte can be used to control the
Measurement rate, Set/reset function, and to command the device into the three allowed operating modes; Standby, Query, and
Continuous. The current Op Mode RAM value can be saved in the EEPROM using the “L” command, and will become the default
mode on subsequent power up. Also, HMC6352 can be put in to Sleep mode for the lowest power consumption.
The Output Mode Byte is located in RAM 0x4E and is not shadowed in the EEPROM, and upon power up the device is in the
Heading output mode. This byte can be changed to get magnetometer data if necessary.
The application environment of the HMC6352 will dictate the most suitable operational mode.
In the Standby Mode the HMC6352 is not performing measurements and is waiting for a command, and can be commanded in to
making a heading measurement by issuing the “A” command. This mode is useful to get data on demand or at random intervals as
long as the application can withstand the time delay in getting the data.
With the Query Mode, the HMC6352 will make a fresh measurement after it is read by the host processor. In this mode the data are
available for immediate read.
The above two modes are the most power efficient readout modes.
In the Continuous Mode the user can choose 1,5,10,or 20 Hz output rate and the HMC6352 will make continuous measurements and
update the output registers. This mode is useful for data demanding applications. In this mode the output can be read by writing 0x43
to the HMC6352 I2C bus.
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HMC6352 2-Axis Digital Compass Module
I2C Bus Overview
HMC6352 employs the 2-wire I2C bus protocol (http://www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf) in the
100 Kb/s data rate, 7 bit addressing mode.
There is a clock line (SCL) and a data SDA line in this bus specification and a host of devices can be connected. The bus can be a
single Master – multi Slave or it can be a Multi-Master configuration. All data transfers are initiated by the Master device which is
responsible for generating the clock signal, and the transfers are 8 bit long. All devices are addressed by its unique 7 bit Address.
After each 8-bit transfer, the Master generates a 9 th clock pulse, and the transmitting device releases the SDA line. The receiving
device will pull the SDA line low to acknowledge (ACK) the successful transfer or leave the SDA high to NACK.
All transitions in the SDA line must occur when SCL is low. This requirement leads to two unique conditions on the bus associated
with the SDA transitions when SCL is high. Master device pulling the SDA low while SCL high is the Start (S) condition, and the
Stop(P) condition when the SDA is pulled high while SCL is high. The I2C protocol also allows for the Restart condition in which
the master device issues a second Start condition without issuing a Stop.
All bus transactions begin with the Master issuing the Start sequence followed by the slave address-byte. The address-byte contains
the slave address; the upper 7 bits (bits7-1), and the LSb. The LSb of the address-byte designates if the operation is read (LSb=1) or
write (LSb=0). At the 9 th clock pulse, the transmitting device will issue the ACK (or NACK). Following these bus events, the
master will send data bytes for a write operation, and the slave will transmit data for a read operation. All bus transactions are
terminated with the Master issuing a Stop sequence.
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HMC6352 2-Axis Digital Compass Module
I2C Implementation
I2C bus can be implemented with either a hardware module or in software. Typical hardware modules will release the SDA and SCL
lines as appropriate to allow the slave device to manipulate these lines. In software implementation care must be taken to perform
these tasks in software.
HMC6352 Interface Commands (Table 1)
Command
(0x77) w
(0x72) r
(0x47) G
(0x67) g
Argument1
EEPROM
Address
EEPROM
Address
RAM
Address
RAM
Address
Argument2
Data
Response1
Response2
Data
Read from EEPROM.
Data
Write to Register.
Data
Read from Register.
(0x53) S
(0x57) W
(0x4F) O
(0x43) C
(0x45) E
(0x4C) L
(0x41) A
Description
Write to EEPROM.
MSByte
LSByte
Sleep.
Wake Up.
Update the Bridge
Offset.
Enter
the
User
Calibration Mode.
Exit
the
User
Calibration Mode.
Save
the
current
MODE into EEPROM
Get Data. Compensate
and Calculate Heading
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HMC6352 2-Axis Digital Compass Module
EEPROM Content
EE Address (hex)
00
01
02
03
04
05
06
07
08
Byte Description
I2C Slave Address
Magnetometer X Offset MSB
Magnetometer X Offset LSB
Magnetometer Y Offset MSB
Magnetometer Y Offset LSB
Time Delay (0 – 255 ms)
Number of Summed measurements(1-16)
Software Version Number
Operation Mode Byte
Factory Default
0x42
**
**
**
**
0x01
0x04
> 0x01
0x50
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HMC6352 2-Axis Digital Compass Module
Timing Requirements
Below are the time delays required by HMC6352 upon receipt of the command to either perform the commanded task or to have the
response available on the I2C bus
Command
(0x77) w
Description
Write to EEPROM.
Time Delay
70 uS
(0x72) r
Read from EEPROM.
70 uS
(0x47) G
(0x67) g
(0x53) S
(0x57) W
(0x4F) O
Write to Register.
Read from Register.
Sleep.
Wake Up.
Update the Bridge
Offset.
Enter
the
User
Calibration Mode.
Exit
the
User
Calibration Mode.
Save
the
current
MODE into EEPROM
Get Data. Compensate
and Calculate Heading
70 uS
70 uS
10 uS
100 uS
6 mS
(0x43) C
(0x45) E
(0x4C) L
(0x41) A
10 uS
14 mS
125 uS
6 mS
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HMC6352 2-Axis Digital Compass Module
Command and Operation Mode Interactions
All commands are acceptable in the Standby Mode. Honeywell strongly recommends using this mode during initial setup stage.
Setting up of the HMC6352 operation mode and its slave address are set up examples. Although execution of all commands in the
Query and Continuous Modes is acceptable, the outcome is not guaranteed.
How to Read Data from HMC6352
1) In Standby Mode
Use “A” command
2) In Query Mode
Send 0x43 and clock out data (See Example 5)
3) In Continuous Mode
Send 0x43 and clock out data (See Example 5)
A is not allowed
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HMC6352 2-Axis Digital Compass Module
Waveform Examples
Red: This is what actually happens on the SDA line.
Green: This is what actually happens on the SCL line.
Blue: This is what the Master tries to make happen on the SDA line.
Black: This is what the senso (Slave) tries to make happen on the SDA line.
Example 1: This example shows how to command the HMC6352 in to Sleep mode by writing the 'S' command to the slave.
START
0
1
0
0
0
0
1
0
ACK
0
1
0
1
0
0
1
1
ACK
STOP
SDA
SCL
M_SDA
S_SDA
0x42
Write to this I2C address
'S'
Command
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HMC6352 2-Axis Digital Compass Module
Example 2: This example shows how to command HMC6352 to read a RAM register by sending the 'g' command and the register
address (0x7F). Note that this example does not show the process of reading the answer. See below for reading.
0x42
Write to this I2C address
'g'
Command
0x7F
Register 0x7F
Example 3: This example shows how to write to a RAM register in the HMC6352 by sending the 'G' command, the register address
(0x7F), and the data byte (0x55) to the sensor.
0x42
Write to this I2C address
'G'
Command
0x7F
Register 0x7F
0x55
Data
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HMC6352 2-Axis Digital Compass Module
Example 4: This example shows how to read a single byte from the HMC6352. The Slave(HMC6352) continues to hold the SDA
line low after the acknowledge (ACK) because the first bit of the data byte is a zero.
0x43
Read from this I2C address
0x55
Data
Example 5: This example shows how to read two bytes from HMC6352 (slave). The slave continues to hold the SDA line low after
the acknowledge because the first bit of the data byte is a zero.
0x43
Read from this I2C address
0x55
Data
0x00
Data
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HMC6352 2-Axis Digital Compass Module
Example 6: The final example shows how to read RAM register 0x7F. First perform a write operation to command the HMC6352 to
read a RAM register and define which register to read (Example 2). The sensor puts the answer in the data buffer. Then perform a
read operation to clock out the answer (Example 4). There is a Stop / Start event in between the write operation and the read
operation. This example is just a combination of Examples 2 and 4, but it is provided to show that reading a register involves both a
write and a read operation.
STOP
0x42
'g'
Write to this I2C address Command
0x7F
Register 0x7F
START
0x43
0x55
Read from this I2C address Data
Honeywell Proprietary
HMR2300
SENSOR PRODUCTS
SMART DIGITAL MAGNETOMETER
Features
•
•
•
•
•
•
•
High Accuracy Over ±1 gauss, <0.5% Full Scale
Range of ±2 gauss, <70 µgauss Resolution
Three Axis (X, Y, Z) Digital Outputs
10 to 154 Samples Per Second, Selectable
RS-232 or RS-485 Serial Data Interfaces
PCB or Aluminum Enclosure Options
6-15 volt DC Unregulated Power Supply Interface
General Description
The Honeywell HMR2300 is a three-axis smart digital
magnetometer to detect the strength and direction of an
incident magnetic field. The three of Honeywell’s
magneto-resistive sensors are oriented in orthogonal
directions to measure the X, Y and Z vector
components of a magnetic field. These sensor outputs
are converted to 16-bit digital values using an internal
delta-sigma A/D converter. An onboard EEPROM
stores the magnetometer’s configuration for consistent
operation. The data output is serial full-duplex RS-232
or half-duplex RS-485 with 9600 or 19,200 data rates.
A RS-232 development kit version is available that
includes a windows compatible demo program,
interface cable, AC adapter, and carrying case.
APPLICATIONS
•
Block Diagram
Attitude Reference
V+
•
Compassing & Navigation
Gnd
Pwr
Cond
Traffic and Vehicle Detection
•
Anomaly Detection
•
Laboratory Instrumentation
•
Security Systems
µC
TX
ADC
UART
•
RX
HMC1002
HMC2003
HMC1001
EEPROM
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HMR2300
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions
Min
Typ
Max
Units
15
Volts
35
mA
Power Supply
Supply Voltage
Pin 9 referenced to Pin 5 (Ground)
Supply Current
Vsupply = 15V, with S/R = On
6.5
27
Temperature
Operating
Storage
Ambient
-40
+85
°C
Ambient, Unbiased
-55
125
°C
Full Scale (FS), Total Field Applied
-2
+2
gauss
Applied Field to Change Output
67
Magnetic Field
Range
Resolution
Accuracy
micro-gauss
RSS of All Errors @+25°C
± 1 gauss
0.01
0.52
%FS
± 2 gauss
1
2
%FS
± 1 gauss
0.1
0.5
%FS
± 2 gauss
1
2
%FS
3 Sweeps Across ± 2 gauss @+25°C
0.01
0.02
%FS
Repeatability Error 3 Sweeps Across ± 2 gauss @+25°C
0.05
0.10
%FS
Gain Error
Applied Field for Zero Reading
0.05
0.10
%FS
Offset Error
Applied Field for Zero Reading
0.01
0.03
%FS
Temperature
Coefficient of Gain
-600
Linearity Error
Hysterisis Error
Best Fit Straight Line @+25°C
±114
Effect
Power Supply
Effect
ppm/°C
From +6 to +15V with 1 gauss
150
ppm/V
PCB Only
28
grams
PCB and Non-Flanged Enclosure
94
PCB and Flanged Enclosure
98
Applied Field
Mechanical
Weight
Vibration
Operating,
5 to 10Hz for 2 Hours
10
mm
10Hz to 2kHz for 30 Minutes
2.0
g
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HMR2300
SENSOR PRODUCTS
Characteristics
Digital I/O Timing
TRESP
Conditions
Min
Typ
Max
Units
1.9
2
2.2
msec
3
3.2
*ddR, *ddS, *ddT
6
6.2
*ddC
40
60
*ddQ
2+(ddx80)
2+Typ
*99 Commands
2+(ddx40)
2+Typ
*99Q
2+(ddx120)
2+Typ
40
41
*99 Commands
ddx40
2+Typ
9600
1.04
19,200
0.52
Power Applied to End of Start-Up
50
(See Timing Diagrams)
*dd Commands (dd = Device ID)
*ddP
TDELAY
TBYTE
TSTARTUP
*dd Commands (dd = Device ID)
39
msec
msec
80
msec
Message
RS-232 COMMUNICATIONS – Figure1 (Timing is Not to Scale)
RS-485 COMMUNICATIONS – Figure 2 (Timing is Not to Scale)
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HMR2300
SENSOR PRODUCTS
GLOBAL ADDRESS (*99) DELAY – Figure 3 (Timing is Not to Scale)
PIN CONFIGURATION
Pin Number
Pin Name
1
NC
No Connection
Description
2
TD
Transmit Data, RS-485 (B+)
3
RD
Receive Data, RS-485 (A-)
4
NC
5
GND
No Connection
6
NC
No User Connection (factory X offset strap +)
7
NC
No User Connection (factory Y offset strap +)
8
NC
No User Connection (factory Z offset strap +)
9
V+
Unregulated Power Input (+6 to +15 VDC)
Power and Signal Ground
PCB DIMENSIONS AND PINOUT – Figure 4 (Connector Not Shown for Clarity)
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HMR2300
SENSOR PRODUCTS
CASE DIMENSIONS – Figure 5
RS-232 UNBALANCED I/O INTERCONNECTS – Figure 6
HOST PC
D
R
HMR2300
TD
RD
RD
TD
GD
GD
R
D
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HMR2300
SENSOR PRODUCTS
RS-485 BALANCED I/O INTERCONNECTS – Figure 7
HOST PC
AD
Z
Z
R
B+
RD(A)
Z = 120 ohms
RD(A)
R
R
TD(B)
TD(B)
D
D
HMR2300
HMR2300
ID = 01
ID = 02
DATA COMMUNICATIONS
The RS-232 signals are single-ended undirectional levels that are sent received simultaneously (full duplex). One
signal is from the host personal computer (PC) transmit (TD) to the HMR2300 receive (RD) data line, and the other is
from the HMR2300 TD to the PC RD data line. When a logic one is sent, either the TD or RD line will drive to about
+6 Volts referenced to ground. For a logic zero, the TD or RD line will drive to about –6 Volts below ground. Since the
signals are transmitted and dependent on an absolute voltage level, this limits the distance of transmission due to
line noise and signal to about 60 feet.
When using RS-485, the signals are balanced differential transmissions sharing the same lines (half-duplex). This
means that logic one the transmitting end will drive the B line at least 1.5 Volts higher than the A line. For a logic
zero, the transmitting end will drive the B line at least 1.5 Volts lower than the A line. Since the signals are
transmitted as difference voltage level, these signals can withstand high noise environments or over very long
distances where line loss may be a problem; up to 4000 feet. Note that long RS-485 lines should be terminated at
both ends with 120-ohm resistors.
Another precaution on RS-485 operation is that when the HMR2300 is in a continuous output mode of operation, the
host PC may have to send repeated escape and carriage return bytes to stop the stream of output data. If the host
can detect a recieved carriage return byte (0D hex), and immediately send the escape-carriage return bytes; then a
systematic stop of continuous output is likely. If manually sent, beware that the half-duplex nature of the interface
corrupt the HMR2300 outbound data while attempting to get the stop command interleaved between the data.
As noted by the Digital I/O timing specification and Figure 3, the HMR2300 has a delayed response feature based on
the programmed device ID in response to global address commands (*99….<cr>). Each HMR2300 will take its turn
responding so that units do not transmit simultaneously (no contension). These delays also apply to the RS-232
interface versions of the HMR2300.
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HMR2300
SENSOR PRODUCTS
COMMAND INPUTS
A simple command set is used to communicate with the HMR2300. These commands can be automated; or typed in
real-time while running communication software programs, such a windows hyperterminal.
Command
Format
Output
Sample Rate
Set/Reset
Mode
Set/Reset
Pulse
Device ID
Baud Rate
Inputs(1)
Average
Readings
Re-Enter
Response
Query Setup
Default
Settings
Restore
Settings
Serial
Number
Software
Version
Hardware
Version
Write Enable
Bytes(3)
Description
ASCII – Output Readings in BCD ASCII Format (Default)
Binary – Output Readings in Signed 16-bit Bianary Format
P = Polled – Output a Single Sample (Default)
C = Continuous – Output Readings at Sample Rate
Escape Key – Stops Continuous Readings
Set Sample Rate to nnn Where:
Nnn = 10, 20, 25, 30, 40, 50, 60, 100, 123, or 154
Samples/sec (Default = 20)
S/R Mode: TN – ON = Auto S/R Pulses (Default)
TF – OFF = Manual S/R Pulses
*ddT Toggles Command (Default = On)
] Character – Single S/R: ]S -> SET = Set Pulse
]R -> RST = Reset Pulse
Toggle Alternates Between Set and Reset Pulse
Read Device ID (Default = 00)
Set Device ID Where nn = 00 to 98
Set Baud Rate to 9600 bps (Default)
*ddWE *ddA
*ddWE *ddB
*ddP
*ddC
Esc
*ddWE *ddR=nnn
ASCII_ON¬
BINARY_ON¬
{x, y, z reading}
{x, y, z stream}
{stream stops}
OK¬
9
10
7 or 28
...
0
3
*ddWE *ddTN
*ddWE *ddTF
*ddWE *ddT
*dd]S
*dd]R
*dd]
*99ID=
*ddWE *ddID=nn
*99WE *99!BR=S
S/R_ON¬
S/R_OFF¬
{Toggle}
SET¬
RST¬
{Toggle}
ID=_nn¬
OK¬
OK¬
BAUD_9600¬
OK¬
BAUD=_19,200¬
ZERO_ON¬
ZERO_OFF¬
{Toggle}
AVG_ON¬
AVG_OFF¬
{Toggle}
OK¬
OK¬
{See Desc.}
7
8
7 or 8
4
4
4
7
3
14
OK¬
BAUD=_9600¬
OK¬
BAUD=_9600¬
or
BAUD=_19,200¬
SER#_nnnn¬
14
S/W_vers:_
nnnn¬
H/W_vers:_
nnnn¬
OK¬
*99WE *99!BR=F
Zero
Reading
Response(2)
*ddWE
*ddWE
*ddWE
*ddWE
*ddWE
*ddWE
*ddWE
*ddWE
*ddZN
*ddZF
*ddZR
*ddVN
*ddVF
*ddV
*ddY
*ddN
*ddQ
*ddWE *ddD
*ddWE *ddRST
*dd#
*ddF
*ddH
*ddWE
14
14
Set Baud Rate to 19,200 bps
(8 bits, no parity, 1 stop bit)
Zero Reading Will Store and Use Current as a Negative
Offset so That the Output Reads Zero Field
*ddZR Toggles Command
The Average Reading for the Current Sample X(N) is:
Xavg=X(N)/2 + X(N-1)/4 + X(N-2)/8 + X(N-3)/16 + ...
*ddV Toggles Command
Turn the “Re-Enter” Error Response ON (*ddY) or OFF
(*ddN). OFF is Recommended for RS-485 (Default = ON)
Read Setup Parameters. Default: ASCII, POLLED, S/R
ON, ZERO OFF, AVG OFF, R ON, ID=00, 20 sps
Change All Command Parameter Settings to Factory
Default Values
Change All Command Parameter Settings to the Last User
Stored Values in the EEPROM
16
22
Output the HMR2300 Serial Number
27
Output the HMR2300 Software Version Number
19
Output the HMR2300 Hardware Version Number
8
9
8 or 9
7
8
7 or 8
3
3
62-72
3
Activate a Write Enable. This is required before
commands: Set Device ID, Baud Rate, and Store
Parameters.
Store
*ddWE *ddSP
DONE¬
8
This writes all parameter settings to EEPROM. These
Parameters
OK¬
values will be automatically restored upon power-up.
Wrong Entry
Re-enter¬
9
A command was not entered properly or 10 characters
Too Many
were typed after an asterisk (*) and before a <cr>.
Characters
Write Enable Off
WE_OFF¬
7
This error response indicates that this instruction requires
Missing WE
a write enable command immediately before it.
Entry
(1) All inputs must be followed by a <cr> carriage return, or Enter, key. Either upper or lower case letters may be used. The device
ID (dd) is a decimal number between 00 and 99. Device ID = 99 is a global address for all units.
(2) The “¬” symbol is a carriage return (hex 0D). The “_” sign is a space (hex 20). The output response will be delayed from the
end of the carriage return of the input string by 2 msec (typ.), unless the command sent as a global device ID = 99.
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HMR2300
SENSOR PRODUCTS
DATA FORMATS
The HMR2300 transmits each X, Y, and Z axis as a 16-bit value. The output data format can be either 16-bit signed
binary (sign plus 15 bits) or a binary coded decimal (BCD) ASCII characters. The command *ddA will select the
ASCII format and *ddB will select the binary format.
The order of ouput for the binary format is Xhi, Xlo, Yhi, Ylo, Zhi, Zlo. The binary format is more efficient for a
computer to interpret since only 7 bytes are transmitted. The BCD ASCII format is easiest for user interpretation but
requires 28 bytes per reading. There are limitations on the output sample rate (see table below) based on the format
and baud rate selected. Examples of both binary and BCD ASCII outputs are shown below for field values between
±2 gauss.
Field
(gauss)
+2.0
+1.5
+1.0
+0.5
0.0
-0.5
-1.0
-1.5
-2.0
BCD ASCII
Value
30,000
22,500
15,000
7,500
00
-7,500
-15,000
-22,500
-30,000
Binary Value (Hex)
High Byte
Low Byte
75
30
57
E4
3A
98
1D
4C
00
00
E2
B4
C3
74
A8
1C
8A
D0
Binary Format: 7 Bytes
XH | XL | YH | YL | ZH | ZL | <cr>
XH = Signed Byte, X axis
XL = Low Byte, X axis
<cr> = Carriage Return (Enter key), Hex Code = 0D
ASCII Format: 28 Bytes
SN | X1 | X2 | CM | X3 | X4 | X5 | SP | SP | SN | Y1 | Y2 | CM | Y3 | Y4 | Y5 | SP | SP | SN | Z1 | Z2 | CM | Z3 | Z4 | Z5
| SP | SP |<cr>
The ASCII characters will be readable on a monitor as sign decimal numbers. This format is best when the user is
interpreting the readings.
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HMR2300
SENSOR PRODUCTS
PARAMETER SELECTION VERSUS OUTPUT SAMPLE RATE
Sample
Rate
(sps)
10
20
25
30
40
50
60
100
123
154
ASCII
9600
yes
yes
yes
yes
no
no
no
no
no
no
19,200
yes
yes
yes
yes
yes
yes
no
no
no
no
Binary
9600
yes
yes
yes
yes
yes
yes
yes
yes
no
no
19,200
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
f3dB
Notch
(Hz)
17
17
21
26
34
42
51
85
104
131
(Hz)
50/60
50/60
63/75
75/90
100/120
125/150
150/180
250/300
308/369
385/462
Command Input
Rate – min.
(msec)
20
20
16
14
10
8
7
4
3.5
3
DEVICE ID
The Device ID command (*ddID=nn) will change the HMR2300 ID number. A Write Enable (*ddWE) command is
required before the device ID can be changed. This is required for RS-485 operation when more than one HMR2300
is on a network. A Device ID = 99 is universal and will simultaneously talk to all units on a network.
BAUD RATE COMMAND
The Baud Rate command (*dd!BR=F or S) will change the HMR2300 baud rate to either fast (19,200 baud) or slow
(9600 baud). A Write Enable (*ddWE) command is required before the baud rate can be changed. The last response
after this command has been accepted will be either BAUD=9600 or BAUD=19,200. This will indicate to the user to
change to the identified new baud rate before communications can resume.
ZERO READING COMMAND
The Zero Reading command (*ddZN) will take a magnetic reading and store it in the HMR2300’s microcontroller.
This value will be subtracted from subsequent readings as an offset. The zero reading will be terminated with another
command input(*ddZF) or a power down condition. This feature is useful for setting a reference attitude or nulling the
earth’s field before anomaly detection.
SET/RESET AND AVERAGE COMMANDS
The set-reset function generates a current/magnetic field pulse to each sensor to realign the permalloy thin film
magnetization. This yields the maximum output sensitivity for magnetic sensing. This pulse is generated inside the
HMR2300 and consumes less than 1mA typically. The Set/Reset Mode command (*ddTN or *ddT) activates an
internal switching circuit that flips the current in a “Set” and “Reset” condition. This cancels out any temperature drift
effects and ensures the sensors are operating in their most sensitive region.
Fluctuations in the magnetic readings can be reduced by using the Average Readings commands (*ddVN or *ddV).
These commands provide a low pass filter effect on the output readings that reduces noise due to Set/Reset
switching and other environmental magnetic effects. The two figures below show the average readings effect for step
and impulse responses.
Switching the set-reset state is not required to sense magnetic fields. A single Set (or Reset) pulse will maximize the
output sensitivity and it will stay that way for months or years. To turn off the internal switching, enter the command
*ddTF or *ddT. In this state the sensors are either in a Set or Reset mode. If the HMR2300 is exposed to a large
magnetic field (>10 gauss), then another set pulse is required to maximize output sensitivity.
In the Set mode, the direction of the sensitive axis’ are shown on the enclosure label and the board dimensions
figure. In the Reset mode, the sensitive field directions are opposite to those shown. By typing *dd], the user can
manually activate a Set or Reset pulse. The S/R pulse commands can be used the continuous read mode to flip
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HMR2300
SENSOR PRODUCTS
between a Set and Reset state. Note that the first three readings immediately after these commands will be invalid
due to the uncertainty of the current pulse to the sensor sample time.
DEFAULT AND RESTORE COMMANDS
The Defaut Settings command (*ddD) will force the HMR2300 to all the default parameters. This will not be a
permanent change unless a Store Parameter command (*ddSP) is issued after the Write Enable command. The
Restore Settings command (*ddRST) will force the HMR2300 to all the stored parameters in the EEPROM.
OUTPUT SAMPLE RATES
The sample rate can be varied from 10 samples per second (sps) to 154 sps using the *ddR=nnn command. Each
sample contains an X, Y, and Z reading and can be outputted in either 16-bit signed binary or binary coded decimal
(BCD) ASCII. The ASCII format shows the standard numeric characters displayed on the host computer display.
Some sample rates may have restrictions on the format and baud rate used, due to transmission time constraints.
There are 7 Bytes transmitted for every reading binary format and 28 Bytes per reading in ASCII format.
Transmission times for 9600 baud are about 1 msec/Byte and for 19,200 baud are about 0.5msec/Byte. The
combinations of format and and baud rate selections are shown in the above Table. The default setting of ASCII
format and 9600 baud will only transmit correctly up to 30 sps. Note the HMR2300 will output a higher data settings,
but the readings may be incorrect and will be at alower output rate than selected.
For higher sample rates (>60 sps), it is advised that host computer settings for the terminal preferences be set so a
line feed <lf> is not appended to the sent commands. This slows down the reception of data, and it will not be able to
keep up with the incoming data stream.
INPUT SIGNAL ATTENUATION
Magnetic signals being measured will be attenuated based on the sample rate selected. The bandwidth, defined by
the 3dB point, is shown in the above Table for each sample rate. The default rate of 20 sps has a bandwidth of 17Hz.
The digital filter inside the HMR2300 is the combination of a comb filter and a low pass filter. This provides a linear
phase response with a transfer function that has zeros in it.
When the 10 or 20 sps rate is used, the zeros are at the line frequencies of 50 and 60 Hz. These zeros provide better
than 125 dB rejection. All multiples of the zeros extend throughout the transfer function. For example, the 10 and 20
sps rate has zeros at 50, 60, 100, 120, 150, 180, ... Hz. The multiples of the zeros apply to all the sample rates
against the stated notch frequencies in the above Table.
COMMAND INPUT RATE
The HMR2300 limits how fast the command bytes can be recieved based on the sample rate selected. The above
Table shows the minimum time between command bytes for the HMR2300 to correctly read them. This is usually not
a problem when the user is typing the commands from the host computer. The problem could arise from an
application program outputting command bytes too quickly.
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HMR2300
SENSOR PRODUCTS
CIRCUIT DESCRIPTION
The HMR2200 Smart Digital Magnetometer contains all the basic sensors and electronics to provide digital indication
of magnetic field strength and direction. The HMR2300 has all three axis of magnetic sensors on the far end of the
printed circuit board, away from the J1 and J2 connector interfaces. The HMR2300 uses the circuit board mounting
holes or the enclosure surfaces as the reference mechanical directions. The complete HMR2300 PCB assembly
consists of a mother board, daughter board, and the 9-pin D-connector (J1).
The HMR2300 circuit starts with Honeywell HMC2003 3-Axis Magnetic Sensor Hybrid to provide X, Y, and Z axis
magnetic sensing of the earth’s field. The HMC2003 contains the AMR sensing bridge elements, a constant current
source bridge supply, three precision instrumentation amplifiers, and factory hand-selected trim resistors optimized
for performance for magnetic field gain and offset. The HMC2003 is a daughter board that plugs into the HMC2300
motherboard, and the hybrid analog voltages from each axis is into analog multiplexors and then into three 16-bit
Analog to Digital Converters (ADCs) for digitization. No calibration is necessary as the HMC2003 hybrid contains all
the compensation for the sensors, and the set/reset routine handles the temperature drift corrections. A
microcontroller integrated circuit receives the digitized magnetic field values (readings) by periodically querying the
ADCs and performs any offset corrections. This microcontroller also performs the external serial data interface and
other housekeeping functions. An onboard EEPROM integrated circuit is employed to retain necessary setup
variables for best performance.
The power supply for the HMR2300 circuit is regulated +5 volt design (LM2931M) with series polarity power inputs
diodes in case of accidental polarity reversal. A charge pump circuit is used to boost the regulated voltage for the
set/reset pulse function going to the set/reset straps onboard the HMC2003. Transient protection absorbers are
placed on the TD, RD, and V+ connections to J1.
APPLICATIONS PRECAUTIONS
Several precautions should be observed when using magnetometers in general:
•
The presence of ferrous materials, such as nickel, iron, steel, and cobalt near the magnetometer will create
disturbances in the earth’s magnetic field that will distort the X, Y, and Z field measurements.
•
The presence of the earth’s magnetic field must be taken into account when measuring other magnetic
fields.
•
The variance of the earth’s magnetic field must be accounted for in different parts of the world. Differences in
the earth’s field are quite dramatic between North America, South America and the Equator region.
•
Perming effects on the HMR2300 circuit board need to be taken into account. If the HMR2300 is exposed to
fields greater than 10 gauss, then it is recommended that the enclosure/circuit boards be degaussed for
highest sensitivity and resolution. A possible result of perming is a high zero-field output indication that
exceeds specification limits. Degaussing wands are readily available from local electronics tool suppliers and
are inexpensive. Severe field offset values could result if not degaussed.
NON-FERROUS MATERIALS
Materials that do not affect surrounding magnetic fields are: copper, brass, gold, aluminum, some stainless steels,
silver, tin, silicon, and most non-metals.
HANDLING PRECAUTIONS
The HMR2300 Smart Digital Magnetometer measures fields within 2 gauss in magnitude with better than 0.1 milligauss resolution. Computer floppy disks (diskettes) store data with field strengths of approximately 10 gauss. This
means that the HMR2300 is many times more sensitive than common floppy disks. Please treat the magnetometer
with at least the same caution as your diskettes by avoiding motors, CRT video monitors, and magnets. Even though
the loss of performance is recoverable, these magnetic sources will interfere with measurements.
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HMR2300
SENSOR PRODUCTS
DEMONSTRATION PCB MODULE KIT
The HMR2300 Demonstration Kit includes additional hardware and Windows software to form a development kit for
with the smart digital magnetometer. This kit includes the HMR2300 PCB and enclosure, serial port cable with
attached AC adapter power supply, and demo software plus documentation on a compact disk (CD). The figure
below shows the schematic of the serial port cable with integral AC adapter. There will be three rotary switches on
the AC adapter. These should be pointed towards the positive (+) polarity, +9 volts, and 120 or 240 VAC; depending
your domestic supply of power.
D9-F
D9-F
data
2
3
2
3
data
5
5
ground
9
9
+9vdc
GRY
BLK
AC adapter
ORDERING INFORMATION
Ordering Number
Product
HMR2300-D00-232
HMR2300-D00-485
PCB Only (No Enclosure), RS-232 I/O
PCB Only (No Enclosure), RS-485 I/O
HMR2300-D20-232
HMR2300-D20-485
Flush-Base Enclosure, RS-232 I/O
Flush-Base Enclosure, RS-485 I/O
HMR2300-D21-232
HMR2300-D21-485
Extended-Base Enclosure, RS-232 I/O
Extended-Base Enclosure, RS-485 I/O
HMR2300-D20-232-DEMO
HMR2300-D21-232-DEMO
Demo Kit, Flush-Base Enclosure, RS-232 I/O
Demo Kit, Extended-Base Enclosure, RS-232 I/O
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
900139 02-04 Rev. H
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Preliminary
Magnetic Products
THREE-AXIS STRAPDOWN MAGNETOMETER
HMR2300r
FEATURES
APPLICATIONS
• Strapdown Magnetometer Replaces Bulky Fluxvalves
• Navigation Systems—Avionics and Marine
• Microprocessor Based Smart Sensor
• Fluxvalve Replacement
• Range of ±2 Gauss—<70 µGauss Resolution
• Can be Slaved to AHRS System
• Readings can Achieve Heading Resolution of 0.02°
• GPS Backup Systems
• Rate Selectable—10 to 154 Samples/Sec.
• Remote Vehicle Monitoring
• Small Size: 2.83 in.—Fits in ML-1 Style Enclosure
• Unpiloted Air Vehicles (UAVs)
• Repeatable and Reliable—MTBF >50,000 hours
• Navigation/Attitude for Satellites
GENERAL DESCRIPTION
Honeywell’s three-axis strapdown magnetometer detects
the strength and direction of the earth’s magnetic field and
communicates the x, y, and z component directly via serial
bus. The HMR2300r is compliant with applicable MIL-STD810E requirements for military and commercial flight systems (see Table 6). It was designed to be a replacement for
bulky fluxvalve magnetic sensors commonly used in aviation systems.
The HMR2300r strapdown magnetometer provides an
excellent replacement of conventional fluxvalve sensors,
commonly used in aviation systems today. The HMR2300r
offers higher reliability (MTBF >50,000 hours) that reduces
maintenance and repair cost. Since the design is strapdown,
as opposed to a gimballed fluxvalve, it has no moving parts
to damage or wear out during severe flight conditions. Low
cost, high sensitivity, fast response, small size, and reliability are advantages over mechanical or other magnetometer alternatives. With an extremely low magnetic field
sensitivity and a user configurable command set, these
sensors solve a variety of problems in custom applications.
A unique switching technique is applied to the solid-state
magnetic sensors to eliminate the effects of past magnetic
history. This technique cancels out the bridge offset as well
as any offset introduced by the electronics. The data is
serially output at either 9,600 or 19,200 baud, using the RS422 or RS-485 standard. The RS-485 standard allows
connection of up to 32 devices on a single wire pair up to
4,000 feet in length. An HMR address can be stored in the
on-board EEPROM to assign one of thirty-two unique ID
codes to allow direct line access. An internal microcontroller handles the magnetic sensing, digital filtering, and all
output communications eliminating the need for external
trims and adjustments. Standard RS-422 or RS-485 drivers provide compliant electrical signalling.
A command set is provided (see Table 4) to configure the
data sample rate, output format, averaging and zero offset.
An on-board EEPROM stores any configuration changes
for next time power-up. In addition, the user has 55 bytes
of EEPROM locations available for data storage. Other
commands perform utility functions like baud rate, device
ID and serial number. Also included in the HMR magnetometer is a digital filter with 50/60 Hz rejection to reduce
ambient magnetic interference.
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HMR2300r
1 Gauss (G) = 1 Oersted (in air), 1G = 79.58 A/m
1G = 10E-4 Tesla, 1G = 10E5 gamma
ppm - parts per million
OPERATING SPECIFICATIONS—Table 1
Characteristic
Conditions
Min
Supply Voltage
Pin 9 referenced to pin 5
6.5
Supply Current
Vsupply=15V (with 120 Ω termination)
Operating Temperature
Ambient
Storage Temperature
Field Range
Max
Unit
15
Volts
55
mA
-40
85
°C
Ambient, unbiased
-55
125
°C
Full scale (FS)—total applied field
-2
+2
Gauss
0.1
1
0.5
2
%FS
Best fit straight line
Linearity Error
Typ
45
±1 Gauss
Hysteresis Error
3 sweeps across ±2 Gauss @ 25 ° C
0.01
0.02
%FS
Repeatability Error
3 sweeps across ±2 Gauss @ 25 ° C
0.05
0.10
%FS
Gain Error
Applied field for zero reading
0.05
0.10
%FS
Offset Error
Applied field for zero reading
0.01
0.03
%FS
RSS of all errors
0.12
1
0.52
2
%FS
Accuracy
±1 Gauss
Resolution
Applied field to change output
Axis Alignment
Variation to 90 degrees
Noise level
67
µGauss
±1
±2
degree
Output variation in fixed field
0.07
±0.13
mGauss
Temperature Effects
Coefficient of gain
Coefficient of offset (with S/R=ON)
-0.06
±0.01
%/° C
Power Supply Effect
From 6 to 15V with 1 Gauss applied
150
ppm/V
Vibration (operating)
5 to 10Hz for 2 hrs.
10Hz to 2KHz for 30 min.
10
2.0
mm
g force
Max. Exposed Field
No perming effect on zero reading
10
Gauss
Weight
Board only
40
grams
Max
Unit
TIMING SPECIFICATIONS—Table 2
Characteristic
Conditions
TRESP
Timing Diagrams (Figs. 1,2)
*dd command (dd=Device ID)
*ddP
*ddRST
*ddC
*99 command (exceptions below)
*ddQ
*99Q
TDELAY
Timing Diagram (Fig. 2)
*99 comand (dd=Device ID)
TBYTE
TSTARTUP
Timing Diagrams (Fig. 1)
Min
Typ
1.9
2.2
2.2
6
40
2 + (dd x 40)
2 + (dd x 80)
2 + (dd x 120)
3.2
3.2
6.5
msec
60
2 + Typ
2 + Typ
2 + Typ
2+ (dd x 40)
2 + Typ msec
9600
19200
Power Applied to start of Start-Up message
1.04
0.52
28
80
msec
140
msec
2
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HMR2300r
RS-485 and RS-422 COMMUNICATIONS—Figure 1
Start
LSB
MSB
Timing is not to scale
Stop
4V
Hi
...
2V
1V
4V
Lo
...
2V
1V
<cr> of Command
TBYTE
HMR2300r Response
TRESP
AAA
AAA AAA
GLOBAL ADDRESS (*99) DELAY—Figure 2
TRESP
Command
Bytes
(*01P<cr>)
Timing is not to scale
HMR ID=01
Response
(XXYYZZVC<cr>)
TDELAY (ID=02)
AAA
AAA
AAA
AAA
AAA AAA AAA AAA
TDELAY (ID=01)
TRESP
Command
Bytes
(*99P<cr>)
Sample
HMR ID=01
Response
(XXYYZZVC<cr>)
HMR ID=00
Response
(XXYYZZVC<cr>)
HMR ID=02
Response
(XXYYZZVC<cr>)
(sps)
9600
19200
9600
19200
(Hz)
(Hz)
Continuous
Reading Period
(msec)
10
yes
yes
yes
yes
17
50/60
101
20
17
50/60
51
25
21
63/75
41.5
30
26
75/90
35
40
34
100/120
24
50
42
125/150
19.6
51
150/180
16.1
85
250/300
9.8
104
308/369
8.1
131
385/462
6.5
ASCII
Rate
60
100
123
Binary
DATA
INVALID
154
f3dB
Notch
Parameter Selections verses Output Sample Rate—Table 3
3
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HMR2300r
COMMAND INPUTS—Table 4
A simple command set is used to communicate with the HMR. These commands can be typed in through a standard
keyboard while running any communications software such as HyperTerminal® in Windows®.
(1)
Response
(2)
Bytes(3) Description
Command
Inputs
Format
*ddWE *ddA
*ddWE *ddB
ASCII_ON ←
BINARY_ON ←
9
10
Output
*ddC
{x, y, z reading}
{x, y, z stream}
{stream stops}
9 or 28
...
0
P=Polled - Output a single sample.
C=Continuous - Output readings at sample rate. (default)
Escape key - Stop continuous readings.
3
Set sample rate to nnn where: nnn= 10, 20, 25, 30, 40,
50, 60, 100, 123, or 154 samples/sec (default 30 sps)
Sample Rate
*ddWE *ddR=nnn OK ←
Set/Reset Mode
*ddWE *ddTN
*ddWE *ddTF
*ddWE *ddT
S/R_ON ←
S/R_OFF ←
{Toggle}
7
8
7 or 8
ASCII - Output readings in BCD ASCII format.
Binary - Output signed 16 bit binary format. (default)
S/R mode: TN -> ON=automatic S/R pulses (default)
TF -> OFF=manual S/R pulses
SET ←
RST ←
{Toggle}
4
4
4
Toggle alternates between SET and RESET pulse.
ID=_n n ←
OK ←
7
3
Read device ID (default ID=00)
Set device ID where nn=00 to 98
Set baud rate to 9600 bps.
Baud Rate
OK ←
BAUD=_9600 ←
OK ←
BAUD=_19,200 ←
14
*99WE *99!BR=S
*99WE *99!BR=F
16
Set baud rate to 19,200 bps. (default)
(8 bits, no parity, 1 stop bit)
Zero Reading
*ddWE *ddZN
*ddWE *ddZF
*ddWE *ddZR
ZERO_ON ←
ZERO_OFF ←
{Toggle}
8
9
8 or 9
Zero Reading will store and use current reading as a
negative offset so that the output reads zero field
*ddZR toggles command. (default=OFF)
Average
Readings
*ddWE *ddVN
*ddWE *ddVF
*ddWE *ddV
AVG_ON ←
AVG_OFF ←
{Toggle}
7
8
7 or 8
The average reading for the current sample X(N) is:
Xavg = X(N)/2 + X(N-1)/4 + X(N-2)/8 + X(N-3)/16 + ...
*ddV toggles command. (default=OFF)
Re-enter
Response
*ddWE *ddY
*ddWE *ddN
OK ←
OK ←
Set/Reset Pulse
*dd]
Device ID
*ddWE *ddID=nn
Query Setup
3
3
{see Description}
62-72
16
Default Settings
*ddWE *ddD
OK ←
BAUD=_19,200 ←
Restore Settings
*ddWE *ddRST
OK ←
BAUD=_9600 or
BAUD=_19,200
14
16
] character - single S/R: ]S -> SET=set pulse
Turn the "Re-enter" error response ON (*ddY) or OFF
(*ddN). OFF is recommended for RS-485 (default=ON)
Read setup parameters. default: binary, Continuous,
S/R ON, ZERO OFF, AVG OFF, R ON, ID=00, 30 sps
Change all command parameter settings to factory
default values.
Change all command parameter settings to the last
user stored values in the EEPROM.
Serial Number
*dd#
SER#_nnnn ←
22
Output the HMR2300r serial number.
Software Version
*ddF
S/W_vers:_ nnnn ←
27
Output the HMR2300r software version number.
Hardware Version
*ddH
H/W_vers:_ nnnn ←
19
Output the HMR2300r hardware version number.
OK ←
3
Activate a write enable. This is required before
commands like Set Device ID, Baud Rate, and others
shown in table.
Store Parameters *ddWE *ddSP
DONE ←
OK ←
8
This writes all parameter settings to EEPROM. These
values will be automatically restored upon power-up.
Too Many
Characters
Re-enter ←
9
A command was not entered properly or 10 characters
were typed after an asterisk (*) and before a <cr>.
WE_OFF ←
7
This error response indicates that this instruction
requires a write enable command immediately before it.
Write Enable
*ddWE
Wrong Entry
Missing WE Entry Write Enable Off
(1) All inputs must be followed by a <cr> carriage return, or Enter, key. Either upper or lower case letters may be used. The device ID (dd) is a
decimal number between 00 and 99. Device ID=99 is a global address for all units.
(2) The “←”symbol is a carriage return (hex 0D). The “_” symbol is a space (hex 20). The output response will be delayed from the end of the
carriage return of the input string by 2 msec (typ.), unless the command was sent as a global device ID=99 (see TDELAY).
4
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HMR2300r
DATA FORMATS
The HMR2300 transmits each x, y, and z axis as a 16-bit
value. The output data format can either be 16-bit signed
binary (sign + 15-bits) or binary coded decimal (BCD) ASCII
characters. The command *ddA will select the ASCII format
and *ddB will select the binary format.
The Validity byte indicates that the onboard microprocessor has properly executed code routines for the selected
mode of operation. The various user selectable modes are
shown in the table below with the corresponding validity
byte and associated ASCII character.
The order of output for the binary format is: Xhi, Xlo, Yhi,
Ylo, Zhi, Zlo. The binary format is more efficient for a computer to interpret since only 9 bytes are transmitted. The
BCD ASCII format is easiest for user interpretation but requires 28 bytes per reading. There are limitations on the
sample rate based on the format and baud rate selected
(see Table 3). Examples of both binary and BCD ASCII outputs are shown below for field values between ±2 Gauss.
Field
BCD ASCII
(Gauss)
+2.0
+1.5
+1.0
+0.5
0.0
-0.5
-1.0
-1.5
-2.0
Value
30,000
22,500
15,000
7,500
00
- 7,500
-15,000
-22,500
-30,000
Zero
Readings
off
off
off
off
on
on
on
on
Binary Value (Hex)
High Byte
75
57
3A
1D
00
E2
C3
A8
8A
Low Byte
30
E4
98
4C
00
B4
74
1C
D0
(1)
XH
|
XL
|
YH
|
|
XH =
XL =
YH =
YL =
ZH =
ZL =
Validity =
Checksum=
<cr> =
ZH
|
ZL
|
Validity
|
Checksum
|
Validity
Character byte
O
4F
S (1)
53
O
4F
V
56
P
50
T
54
P
50
W
57
28 bytes
SN | X1 | X2 | CM | X3 | X4 | X5 | SP | SP | SN | Y1 | Y2 | CM | Y3 | Y4 |
Y5 | SP | SP | SN | Z1 | Z2 | CM | Z3 | Z4 | Z5 | SP | SP | <cr>
The ASCII characters will be readable on a monitor as
signed decimal numbers. This format is best when the user
is interpreting the readings.
9 bytes
YL
Auto
Set/Reset
off
on
off
on
off
on
off
on
Default mode. This mode can be reset using the
*99we, *99rst command sequence.
ASCII Format:
Output Readings—Table 5
Binary Format:
Average
Readings
off
off
on
on
off
off
on
on
<cr> = carriage return (Enter Key), Hex code = 0D
SP = space, Hex code = 20
SN (sign) = - if negative, Hex code = 2D
SP if positive, Hex code = 20
CM (comma) = , if leading digits are not zero, Hex code = 2C
SP if leading digits are zero, Hex code = 20
X1, X2, X3, X4, X5 = Decimal equivalent ASCII digit
X1, X2, X3 = SP if leading digits are zero, Hex code = 20
<cr>
signed high byte, x axis
low byte, x axis
signed high byte, y axis
low byte, y axis
signed high byte, z axis
low byte, z axis
Validity byte is described below
Checksum is the ones complement of
the sum of the first seven bytes
carriage return (Enter Key), Hex code = 0D
RS-232 to RS-485
B&B Electronics
#485PTBR
Output data format is in counts (sign + 15 bit magnitude)
Scale factor is 1 gauss = 15,000 counts
Output measurement range = ± 30,000 counts
RS-232
TD
RD
GD
The binary characters will be unrecognizable on a monitor
and will appear as strange symbols. This format is best
when a computer is interpreting the readings.
Checksum = ones complement of the sum
(XH + XL + YH + YL + ZH + ZL + Validity)
2RD
3TD
7GD
120VAC
TD(A)
TD(B)
RD(A)
RD(B)
SG
+12VDC
TERM.
HMR2300r
RS-422
Rx-lo
Rx-hi
Tx-lo
Tx-hi
Gnd
Pwr
1
8
3
2
5
9
J1 Pin
connector
+12VDC
INTERFACE CONVERTER TO RS-232—FIGURE 3
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HMR2300r
DATA COMMUNICATIONS
the escape code immediately after it, then a systematic
stop reading will occur. If an operator is trying to stop
readings using the keyboard, then several (if not many)
escape key entries must be given, since the RS-485 lines
share the same wires for transmit and receive. If an escape
key is entered during the time data is sent from the
HMR2300r, then the two will produce an erroneous
character that will not stop the data stream. The data stream
stop only when the escape key is pressed during the time
the HMR2300r is not transmitting.
The RS-422 signals are balanced differential signals that
can send and receive simultaneously (full-duplex). The RS485 signals are also balanced differential levels but the
transmit and receive signals share the same two wires.
This means that only one end of the transmission line can
transmit data at a time and the other end must be in a
receive mode (half-duplex).
The RS-422 and RS-485 lines must be terminated at both
ends with a 120 ohm resistor to reduce transmission errors.
There are termination resistors built into the HMR2300r as
shown in Figures 4 and 5.
Computer
The signals being transmitted are not dependent on the
absolute voltage level on either Lo or Hi but rather a
difference voltage. That is, when a logic one is being
transmitted, the Tx line will drive about 1.5 volts higher than
the Rx line. For a logic zero, the Lo line will drive about 1.5
volts lower than the Hi line. This allows signals to be
transmitted in a high noise environment, or over very long
distances, where line loss may otherwise be a problem—
typically 4,000 feet. These signals are also slew-rate limited
for error-free transmission. The receiver has a common
mode input range of -7 to +12 volts. The signal connections
are shown in Figure 6.
HMR
Rx-lo
Z
D
Z
Rx-hi
R
Tx-lo
Z
R
Z
Tx-hi
D
Z=120Ω
RS-422 Balanced (full-duplex)—Figure 4
Computer
Lo (A)
HMR
Lo
D
R
Z
Note: When the HMR2300r is in a continuous read mode
on the RS-485 bus, it may be necessary to enter several
escape keys to stop the readings. If the computer taking
the readings can detect a carriage return code and send
Z
R
D
Hi (B)
Hi
Z=120Ω
RS-485 Balanced (half-duplex)—Figure 5
PINOUT DIAGRAMS—FIGURE 6
J1 Pins
+6.5 to +15VDC power - 9
connected to P1 pin 6 - 7
+6.5 to +15VDC return - 5
Tx-lo (RS-422) or Lo (RS-485) - 3
Rx-lo (RS-422) - 1
J1 Pin#
1
2
3
4
5
6
7
8
9
10
P1 Sockets
10 - nc
10 - for manufacturers use only
for manufacturers use only - 9
8 - Rx-hi (RS-422)
8 - for manufacturers use only
nc - 7
6 - connected to P1 pin 2
6 - connected to J1 pin 7
+6.5 to +15VDC power - 5
4 - Chassis ground
4 - Chassis ground
+6.5 to +15VDC return - 3
2 - Tx-hi (RS-422) or Hi (RS-485)
2 - connected to J1 pin 6
nc - 1
Pin Assignment
Rx-lo (RS-422)
Tx-hi (RS-422) or Hi(B) (RS-485)
Tx-lo (RS-422) or Lo(A) (RS-485)
Chassis ground
+6.5 to +15VDC return
connected to P1 pin 2
connected to P1 pin 6
Rx-hi (RS-422)
+6.5 to +15VDC power
(no connect)
P1 Pin#
1
2
3
4
5
6
7
8
9
10
Pin Assignment
(no connect)
connected to J1 pin 6
+6.5 to +15VDC return
Chassis ground
+6.5 to +15VDC power
connected to J1 pin 7
(no connect)
for manufacturers use only
for manufacturers use only
for manufacturers use only
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HMR2300r
BOARD DIMENSIONS—FIGURE 7
All Dimensions in inches
J1
TOP-SIDE OF CIRCUIT BOARD ASSEMBLY
AAA
A
AAA
A
AAA
A
AAA
A
AAA
A
AAA
A
AAA
A
AAA
A
AAA
A
AAA
A
P1
+Y
+X
(FWD)
J1
SAMTEC TSW-105-06-T-D
10-PIN HEADER
P1
SAMTEC SSQ-105-01-S-D
10-SOCKET HEADER
+Z axis
(Down)
.39 MAX
COMPONENT
HEIGHT
.12 MAX
.060
COMPONENT
HEIGHT
BACK-SIDE OF CIRCUIT BOARD ASSEMBLY
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HMR2300r
QUALITY AND ENVIRONMENTAL CONDITIONS—TABLE 6
Parameter
Method and Test Levels
Printed Circuit Board
Conforms to IPC-6011 and IPC-6012, Class 3, using FR-4 laminates and prepreg per IPC-4101/21.
Assembly and Workmanship
Conforms to J-STD-001, Class 3, and IPC-A-610, Class 3, respectively.
Electrostatic Sensitive Devices
The HMR2300r shall be treated as an Electrostatic Sensitive Device (ESD) and precautionary
handling and marking shall apply.
Mean Time Between Failure (MTBF) The MTBF of the HMR2300r is 25,000 hours minimum under the environmental conditions specified.
Altitude
The HMR2300r is capable of withstanding altitudes per MIL-STD-810E, Method 520.1, Procedure III.
Fungus
The HMR2300r is constructed with non-nutrient materials and will withstand, in both operation and
storage conditions, exposure to fungus growth per MIL-STD-810E, Method 508.4
Shock
The HMR2300r will perform as specified following exposure to shock IAW MIL-STD-810E, Method
513.4, Table 516.4, Procedure I, V, and VI. Functional shock (20g, 11ms, 3 shocks in both directions of
3 axes) and crash hazard shock (40g, 11ms, 2 shocks in both directions of 3 axes.
Vibration
The HMR2300r will perform as specified during exposure to random vibration per MIL-STD-810E
Method 514.4, Category 10, Figure 514.4, random vibration, 4 Hz - 2000 Hz (0.04g^2/Hz to 0.0015
g^2/Hz), 3 hr./axis operating.
Salt Fog*
The HMR2300r, when clear coated, will operate as specified after 48 hrs. exposure to a salt
atmosphere environment per MIL-STD-810E, Method 509.3, Procedure I *User must provide
polyurethane clear coat to board.
Explosive Atmosphere
The HMR2300r will not ignite an explosive atmosphere when tested IAW MIL-STD-810E, Method
511.3, Procedure I.
Humidity
Method 507.3, Procedure III.
Temperature
10 cycles at -54° C to +71 degC operating (approx. 4 hours/cycle including stabilization time).
EMI
The HMR2300r will meet the requirements of MIL-STD-461C, Notice 2, and MIL-STD-462, Notice 5.
APPLICATIONS PRECAUTIONS
the earth’s magnetic field are quite dramatic between
North America, South America and the Equator region.
Several precautions should be observed when using magnetometers in general:
•
The presence of ferrous materials—such as nickel, iron,
steel, cobalt—near the magnetometer will create disturbances in the earth’s magnetic field that will distort x,
y and z field measurements.
•
The presence of the earth’s magnetic field must be taken
into account when measuring other x, y and z, fields.
•
The variance of the earth’s magnetic field must be accounted for in different parts of the world. Differences in
•
Perming effects on the HMR board need to be taken
into account. If the HMR board is exposed to fields
greater than 10 Gauss (or 10 Oersted), then the board
must be degaussed. The result of perming is a high zero
field output code that may exceed specification limits.
Degaussing devices are readily available from local electronics outlets and are inexpensive. If the HMR board is
not degaussed, zero field offset values may result.
ORDERING INFORMATION
HMR2300r-422
HMR2300r-485
RS-422 Communication Standard
RS-485 Communication Standard
Customer Service Representative
1-800-238-1502 fax: (612) 954-2257
E-Mail: [email protected]ll.com
Honeywell reserves the right to make changes to any products or technology herein to improve reliability, function or design. Honeywell does not assume any liability
arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
900232 Rev. B
1/99
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SENSOR PRODUCTS
Digital Compass Module
APPLICATIONS
Oceanographic
– Marine Compassing
– Positioning of Buoys,
Underwater Structures
HMR3000
Drilling
– Down Hole and Directional
Attitude Reference
Heading
– Navigation of Unmanned
Vehicles
– Avionic Compassing
Integration with GPS
– Dead Reckoning
Satellite Antenna Positioning
E
lectronic compass module that
provides heading, pitch and roll
output for navigation and guidance systems. Honeywell’s
solid state magnetoresistive
sensors make this strapdown
compass both rugged and reliable. This compass provides
fast response time up to 20
Hertz and high heading accuracy of 0.5° with 0.1° resolution.
Laser Range Finders
– Surveying Applications
FEATURES AND BENEFITS
Fast Response Time
Built with solid state magnetic sensors and no moving parts improves response time,
allowing faster updates compared to gimballed fluxgates.
Small Size
Available as a circuit board 1.2 x 2.95 inches, weighing less than one ounce, or in an
aluminum enclosure.
Low Power
Operates with less than 35 mA, allowing for long operation with a battery.
High Accuracy
Accuracy better than 0.5° with 0.1° resolution for critical positioning applications.
Wide Tilt Range
Tilt range of ±40° for both the roll and pitch allows operation for most applications.
Hard Iron Compensation
Calibration routines to compensate for distortion due to nearby ferrous objects and
stray fields, such as vehicles.
User Configurable Features
User settings of baud rate, update rate, output format, units, filter settings, deviation
angles, alarms and warnings are stored internally in non-volitile memory.
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HMR3000
SENSOR PRODUCTS
INTERFACE SIGNAL DESCRIPTIONS
(HPR, RCD and CCD), and an ASCII heading output for
a digital display. HDG, HDT and HPR are the most
commonly used sentences; the formats are given below.
Communication
HMR3000 communicates with an external host via RS232 or RS-485 electrical standard through simple ASCII
character strings. ASCII characters are transmitted and
received using 1 Start bit, 8 Data bits, (LSB first, MSB
always 0), no parity, and 1 Stop bit. Baud rate is user
configurable to 1200, 2400, 4800, 9600, 19,200 or
38,400. HMR3000 responds to all valid inputs received
with correct checksum value.
$HCHDG, Heading, Deviation, Variation
$HCHDG,85.5,0.0,E,0.0,E*77
$HCHDT, Heading, True
$HCHDT,271.1,T*2C
$PTNTHPR, Heading, Pitch and Roll
$PTNTHPR, Heading,Heading Status,Pitch,Pitch
Status,Roll,Roll Status*hh<cr><lf>
$PTNTHPR,85.9,N,-0.9,N,0.8,N*2C
Compass Output
HMR3000 can output three NMEA standard sentences,
(HDG, HDT and XDR), three proprietary sentences
The table shows pin assignments for the 9-pin D-shell connector. Power input can be either regulated 5V dc or
unregulated 6V to 15V. Only one of the two power pins (9 or 8) should be connected in a given installation.
Name
In/Out Pin Description
Typ
Min (1) Max (1) Units
TxD / B
Out
2
RS-232 transmit out / RS-485
—
-18
18
V dc
RxD / A
In
3
RS-232 receive in / RS-485
—
-18
18
V dc
GND
In
5
Power and signal common
—
6-15V
In
9
Unregulated power input
6 – 15
0
30
V dc
5V
In
8
Regulated power input
5 ± 5%
0
7.5
V dc
Oper / Calib (2)
In
1
Operate / Calibrate (3) input (open = Operate)
0– 5
-20
20
V dc
Run / Stop (2)
In
6
Run / Stop (3) input (open = Run)
0– 5
-20
20
V dc
Ready / Sleep (2)
In
4
Ready / Sleep (3) input (open = Ready)
0– 5
-20
20
V dc
Cont / Reset (2)
In
7
Continue / Reset (3) input (open = Continue)
0– 5
-20
14
V dc
(1) Absolute maximum ratings.
(2) Sink current requirement; 200 (Typ) 400 (Max) µA.
(3) Open input = high logic state.
2
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HMR3000
SENSOR PRODUCTS
SPECIFICATIONS
Parameter
Value
Comments
Heading
Accuracy (1)
< 0.5° RMS (2)
< 1.5° RMS
Repeatability (3) (4)
± 0.3°
Resolution
0.1°
Units
degrees / mils
Dip < 50° , Tilt <20° *
Dip < 75° , Tilt <20° *
User selectable
Pitch and Roll
Range
± 40°
Accuracy
± 0.4°
± 0.6°
Repeatability (3) (4)
± 0.2°
Tilt < 20°
Tilt > 20° *
Resolution
0.1°
Units
degree/ mils
User selectable
Magnetic Field (3)
Dynamic Range
± 1.0 Gauss max
Resolution
1 mGauss
Supply Voltage
5.0 Vdc regulated
6 - 15 Vdc unregulated
Power
35 mA @ 6 Vdc
13 mA
2.0 mA
Serial
RS-232
RS-485
Baud Rate
1200 to 38400 bps
Standard
NMEA 0183
Update Modes
Continuous
Strobed
Weight
0.75 oz (22 g)
3.25 oz (92 g)
Circuit card only
Housed
Dimensions
1.2 x 2.95 x 0.760
1.5 x 4.2 x 0.88
Circuit card
Housed compass
± 0.5 Gauss range
Electrical (4)
Normal operation
STOP Mode
SLEEP Mode
Interface
Half Duplex
1/min to 20 Hz per sentence
selectable averaging
Physical (4)
Environment (5)
Operating Temp
-20 to 70° C
Storage Temperature
-35 to 100° C
Shock
30 inch drop
MIL-STD-810E; TM 516.4
Vibration
20 - 2000 Hz
Random 2 hrs/axis
MIL-STD-810E; TM 514.4
PCB
IPC 6012
Assembly
IPC 610
Manufacturing
Class II or better
4.Typical
5.Meet or exceed.
* Device orientation not to exceed 75°
during operation or storage—may cause
temporary loss of accuracy.
1.Heading accuracy assumes the Earth’s
magnetic field is only disturbed by hard iron
fields, and has been compensated through
calibration.
2.Calculated values.
3.Guaranteed by characterization or design.
3
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HMR3000
SENSOR PRODUCTS
SPECIFICATIONS
HMR3000 CONNECTION DIAGRAM—COMPUTER RS232 TO HMR3000
RS-232 computer pins
HMR3000 pins
2
3
5
9
RX 2
TX 3
GND 5
RS-232 computer pins
TX
RX
GND
V+
5 Vdc Reg.
Regulated voltage
source
Unregulated Supply
4.200 (10.67)
Z
0.188
(0.46)
Regulated Supply
AA
A
AA
A
AA
A
A
AA
A
AA
0.812
(2.06
)
Φ 0.150 (0.38)
S/N 300062
RS
232
485
Y
Pitch
Roll
1.500 (3.81)
HMR3000
Compass Module
Forward
X
3.250 (8.26)
0.188
(0.46)
2 TX
3 RX
5 GND
8 V+
RX 2
TX 3
GND 5
6-15 Vdc
ac adapter
HMR3000 pins
inches
(centimeters)
0.062
0.062 (
(0.16)
0.16)
ORDERING INFORMATION
Type
RS-232 to RS-485
B & B Electronics #485TBLED
SD Control
Echo Off
RS-232
TD
RD
GD
2 RD
3 TD
7 GD
Shield
TD(A)
TD(B)
RD(A)
RD(B)
GND
+12V
VAC
1
2
3
4
5
6
7
+12VDC
Output
Enclosure
HMR3000-Demo-232* ..... RS232
RS-485
HMR3000-D00-232 ......... RS232 ....... None
HMR3000-D21-232 ......... RS232 ....... Extended Base
(B)
(A)
2
3
RS-485
Gnd
Pwr
5
9
Gnd
+12VDC
DB9 socket
connector
HMR3000-D00-485 ......... RS485 ....... None
HMR3000-D21-485 ......... RS485 ....... Extended Base
*Development Kit includes one module in aluminum enclosure,
cabling with power supply, demonstration software for PC running
Windows™ and User’s Manual.
Honeywell reserves the right to make changes to any products or technology herein to improve reliability, function or design. Honeywell does not assume any liability
arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Solid State Electronics Center
12001 State Highway 55
Plymouth, MN 55441
1-800-323-8295
900204 Rev. B
12/99
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HMR3100
SENSOR PRODUCTS
DIGITAL COMPASS SOLUTION
Features
•
•
•
•
•
•
5° Heading Accuracy, 0.5° Resolution
2-axis Capability
Small Size (19mm x 19mm x 4.5mm), Light Weight
Advanced Hard Iron Calibration Routine for Stray
Fields and Ferrous Objects
0° to 70°C Operating Temperature Range
2.6 to 5 volt DC Single Supply Operation
General Description
Top Side
The Honeywell HMR3100 is a low cost, two-axis
electronic compassing solution used to derive heading
output. Honeywell’s magnetoresistive sensors are
utilized to provide the reliability and accuracy of these
small, solid state compass designs. The HMR3100
communicates through binary data and ASCII
characters at four selectable baud rates of 2400, 4800,
9600, or 19200. This compass solution is easily
integrated into systems using a simple USART
interface.
Bottom Side
APPLICATIONS
• Vehicle Compassing
Block Diagram
• Hand-Held Electronics
VCC
• Telescope Positioning
• Navigation Systems
RXD
HMC1022
CPU
TXD
RTS
GND
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HMR3100
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions
Min
Typ
Max
Units
Heading
±5
deg RMS
Resolution
0.5
deg
Repeatability
±3
deg
±2
gauss
6
milli-gauss
Accuracy
Level
Magnetic Field
Range
Maximum Magnetic Flux Density
Resolution
Electrical
Input Voltage
Current
Unregulated
2.6
3
5
volts DC
Normal Mode (Average 1Hz Sampling)
0.1
0.2
0.5
mA
1
µA
Sleep Mode
Calibration
6.1
7.3
17.3
mA
USART 9600.N.8.1
2400
9600
19200
Baud
Continuous or Polled
-
2
20
Hz
Digital Interface
USART
Update Rate
Connector
8-Pin Wide DIP
-
Physical
Dimensions
Circuit Board Assembly
19 x 19 x
mm
4.5
Weight
1.5
grams
Environment
Temperature
Operating
0
-
+70
°C
Storage
-40
-
+110
°C
Circuit Description
The HMR3100 Digital Compass Solution circuit board includes the basic magnetic sensors and electronics to provide
a digital indication of heading. The HMR3100 has a Honeywell HMC1022 two-axis magnetic sensor on board. The
HMR3100 allows users to derive compassing (heading) measurements when the board is in a reasonably horizontal
(flat) position.
The HMR3100 circuit starts with the HMC1022 two-axis magnetic sensors providing X and Y axis magnetic sensing
of the earth’s field. These sensors are supplied power by a switching transistor to conserve power with battery
operated products. The sensor output voltages are provided to a dual operational amplifier and then to analog to
digital converters (ADC) onboard a microcontroller (µC) integrated circuit. The microcontroller integrated circuit
periodically samples the amplified sensor voltages, performs the offset corrections, and computes the heading. This
microcontroller also performs the external serial data interface and other housekeeping functions such as the
calibration routine.
The power supply for the HMR3100 circuit board is to be about a +3 to +5 volt range allowing the user to provide a
single lithium battery to logic level supply voltages. The power supply architecture is a single ground system for
single ended supply sources (+ and ground return).
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HMR3100
SENSOR PRODUCTS
Note the “North Arrow” printed on the HMR3100 circuit board top side. This is the mechanical reference for product
alignment purposes. When placed on the development kit’s RS-232 motherboard assembly, this arrow also points
toward the 9-volt batterypin block on the motherboard (away from the RJ-11 jack).
Pin Configuration
Pin Number
1
2
3
4
5
6
7
8
Pin Name
VCC
NC
RTS
NC
TXD
RXD
GND
NC
Description
Power Supply Input
No Connection
Ready To Send Input
No Connection
Transmit Data Output
Receive Data Input
Power and Signal Ground
No Connection
The HMR3100 board is 0.77” on each side with eight pins in groups of four spaced at 0.6” apart in wide-DIP format.
Seated height is approximately 0.275”. See Figure 1 for further mechanical details.
USART Communication Protocol
HMR3100 module communicates through binary data and ASCII characters at four selectable baud rates of 2400,
4800, 9600, or 19200. The default data bit format is USART 9600.N.8.1. The baud rate selection is determined by
the position of jumpers J1 and J3. These jumpers are zero ohm SMT resistors (jumpers) and are normally high (logic
1) when removed, and grounded (logic 0) when in place. At 2400 baud, no jumpers are present for a 1,1 logic
presentation. At 4800 baud J3 is present for a 1,0 logic presentation. The factory default setting of 9600 baud is
created by a jumper present on J1 for a 0,1 logic presentation. With J1 and J3 jumpers present for a 0,0 logic
presentation, the compass module works at 19200 baud. See Figure 1 for jumper locations. Jumper J2 is for factory
testing, and J4 is for Y-axis inversion should the end-item mount of the HMR3100 module be upside down (pins up).
0.77”
xtal
Pin 1
Pin 8
µC
Pin 4
Pin 5
J1 J2 J3 J4
0.77”
Top Side
Figure 1
HMR3100 Pinout
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HMR3100
SENSOR PRODUCTS
The HMR3100 sends data via the TXD line (Pin 5) in standard serial bus form at logic levels, but uses the RTS (Pin
3) and RXD (Pin 6) to select the three active modes of operation. Normally RTS and RXD input lines are left high
until data or hard-iron calibration is needed from the HMR3100. The RXD line is left high unless a calibration is
requested. The RTS line will be either be pulsed low or held low to initiate an active mode. Otherwise a low-power
sleep mode is the default state. The RXD and RTS data inputs are passively pulled high via the microcontroller if left
open.
Normal Mode
When the host processor (external to the HMR3100), sends a RTS low pulse to the RTS pin, the HMR3100 will send
status/heading data via the TXD pin. The host shall hold the RXD pin high during this mode. The RTS shall be held
high when not pulsed. The HMR3100 will return to sleep mode when RTS is left high after the three-byte
status/heading data packet is sent. Up to 20 heading queries per second can be accomplished given fast enough
baud rates. A caution is advised that average current draw is proportional to supply voltage and amount of queries
handled. At the 20 Hz rate, 1 to 5 milliamperes of current is consumed with lesser query rates taking advantage of
the less than one-microampere sleep mode current draw between queries. Figure 2 shows the normal mode timing
diagram.
Figure 2
Normal Mode Timing Diagram
Continuous Mode
When the host processor (external to the HMR3100), holds the RTS input low, the HMR3100 will continuously send
heading data via the TXD pin. The host shall hold the RXD pin high during this mode. The HMR3100 shall output the
three-byte status/heading data packet at about a 2Hz rate. The HMR3100 will return to sleep mode when RTS is
returned high. Figure 3 shows the continuous mode timing diagram.
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HMR3100
SENSOR PRODUCTS
Figure 3
Continuous Mode Timing Diagram
Calibration Mode
When the host processor pulses low the RTS pin, and sends the RXD pin to a low logic level, the HMR3100 is in
hard-iron calibration mode. This calibration is only for nearby magnetized metals (hard-iron) that are fixed in position
with the HMR3100. At a moderate rate (5 seconds or more per rotation), rotate the HMR3100/host assembly two
complete circles (on a flat, non-magnetic surface if possible) to allow the HMR3100 to take measurements for
compass calibration. At the completion of the rotations, return the RXD to a high logic level. The HMR3100 will return
to sleep mode until another active mode has been initiated. Upon initiation of the calibration mode, the
microcontroller shall output an ASCII STA (53 54 41 hex) indicating a start of calibration and then an ASCII RDY (52
44 59 hex) at the completion of the rotations and the RXD line returned high. Figure 4 shows the calibration mode
timing diagram.
Figure 4
Calibration Mode Timing Diagram
Figure 4
Calibration Mode Timing Diagram
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HMR3100
SENSOR PRODUCTS
Data Description
The HMR3100’s onboard microcontroller sends a three byte status/heading data packet reply as the RTS line is
brought low. The data is normally formatted in binary with the first byte being either 80(hex) or 81(hex).
If that first byte LSbit is flagged high (81 hex), it means magnetic distortion maybe present and a hard-iron calibration
should be performed. Many end users may choose to ignore this indication in portable applications.
The remaining two bytes are the heading (in degrees) in MSB to LSB format. There is some data interpretation
needed to derive the heading. For example, the 80 02 85 (hex) Byte pattern correlates to 322.5 degrees.
This is done by taking the MSB hex value, converting it to decimal (base ten) representation (e.g. 02 decimal) and
multiplying it by 256. Then the LSB is decimalized (e.g. 85(hex) to 133(decimal)) and added to the 512(decimal)
MSB. The total (512+133=645) is then divided by two to arrive at a 322.5 degree heading. This data format permits
the 0.5° resolution in two bytes by doing the binary to decimal conversion and division by two.
Development Kit
The HMR3100 Development Kit includes additional hardware and Windows demo program software to form a
development kit for electronic compassing. This kit includes the appropriate HMR3100 Printed Circuit Board (PCB)
module soldered to an intermediate circuit board using a 0.8” spacing pin arrangement. The intermediate board
assembly plugs into an RS-232 motherboard with a serial port connector. In addition, a four-foot serial port cable (RJ11 to D-9F), nine-volt battery clip, demo program software, and user’s guide is included. The RS-232 motherboard
incorporates a 5-volt regulator integrated circuit to provide the necessary voltages to the onboard RS-232 converter
integrated circuit and the HMR3100 daughter-board. A nine-volt battery clip is included, but other DC input voltages
between 7 and 15 volts may be used. Supply currents are nominally around 8mA plus the HMR3100 current draw.
The RS-232 motherboard also contains a six-contact modular jack (RJ-11) for a compact RS-232 interface to a
personal computer serial port. Ground, RTS, RXD, and TXD data lines are brought out to the jack with two contacts
left open. The demo software stimulates the RTS and RXD lines and reads the data from the TXD line for graphical
display on the host computer. No other support software is available. Figure 5 shows the kit board assemblies.
Figure 5
HMR3100 Kit Hardware
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HMR3100
SENSOR PRODUCTS
Ordering Information
Ordering Number
HMR3100
HMR3100-Demo-232
Product
PCB Module Only
PCB Module with Development Kit
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
900268 02-04 Rev. A
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HMR3200/HMR3300
SENSOR PRODUCTS
DIGITAL COMPASS SOLUTIONS
Features
x
x
x
x
x
x
x
x
1° Heading Accuracy, 0.1° Resolution
0.5° Repeatability
r60° Tilt Range (Pitch and Roll) for HMR3300
Small Size (1.0” x 1.45” x 0.4”), Light Weight
Compensation for Hard Iron Distortions, Ferrous
Objects, Stray Fields
15Hz Response Time
-40° to 85°C Operating Temperature Range
6-15 volt DC unregulated or 5 volt regulated supply
General Description
The Honeywell HMR3200/HMR3300 are electronic
compassing solutions for use in navigation and
guidance systems. Honeywell’s magnetoresistive
sensors are utilized to provide the reliability and
accuracy of these small, solid state compass designs.
These compass solutions are easily integrated into
systems using a UART or SPI interface in ASCII
format.
The HMR3200 is a two-axis compass, and can be used
in either vertical or horizontal orientations.
The HMR3300 is a three-axis, tilt compensated
compass that uses a two-axis accelerometer for
enhanced performance up to a r60° tilt range.
APPLICATIONS
Block Diagram
x Compassing & Navigation
x Attitude Reference
Vcc
SCK
V+
SPI
SDI
x Satellite Antenna Positioning
SDO
CS
Volt
Reg
x Platform leveling
CAL
PC
Vcc
Multi-ADC
x Laser Range Finders
UART
HMC1022
x GPS Integration
TX
RX
xout
yout
Vcc
2-axis
accel
EEPROM
HMC1021
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HMR3200/HMR3300
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions
Min
Typ
Max
Units
Heading
Accuracy
Level
1.0
0° to r30° (HMR3300 only)
3.0
r30° to r60° (HMR3300 only)
4.0
Resolution
Hysteresis
Repeatability
Pitch and Roll
Range
Accuracy
Null Accuracy*
deg RMS
0.1
deg
HMR3200
0.1
0.2
HMR3300
0.2
0.4
HMR3200
0.1
0.2
HMR3300
0.2
0.4
deg
deg
(HMR3300 only)
Roll and Pitch Range
r 60
0° to r 30°
0.4
0.5
r 30° to r 60°
1.0
1.2
Level
0.4
-20° to +70°C Thermal Hysterisis
1.0
-40° to +85°C Thermal Hysterisis
5.0
deg
deg
deg
Resolution
0.1
deg
Hysteresis
0.2
deg
Repeatability
0.2
deg
r2
gauss
Magnetic Field
Range
Maximum Magnetic Flux Density
Resolution
0.1
0.5
milli-gauss
-
15
volts DC
HMR3200
18
20
mA
HMR3300
22
24
mA
-
19200
Baud
Electrical
Input Voltage
Current
Unregulated
6
Digital Interface
UART
ASCII (1 Start, 8 Data, 1 Stop,
2400
0 Parity) User Selectable Baud Rate
SPI
Update
CKE = 0, CKP = 0 Psuedo Master
Continuous/Strobed/Averaged
HMR3200
15
HMR3300
8
Hz
Connector
In-Line 8-Pin Block (0.1” spacing)
* Null zeroing prior to use of the HMR3300 and upon exposure to temperature excursions beyond the Operating
Temperature limits is required to achieve highest performance.
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HMR3200/HMR3300
SENSOR PRODUCTS
Characteristics
Conditions
Min
Typ
Max
Units
Physical
Dimensions
Circuit Board Assembly
25.4 x 36.8 x
mm
11
Weight
HMR3200
7.25
HMR3300
7.5
grams
Environment
Temperature
Operating (HMR3200)
-40
-
+85
°C
Operating (HMR3300)
-20
-
+70
°C
Storage
-55
+125
°C
Pin Configuration
Pin Number
Pin Name
Description
1
SCK
2
RX/SDI
Serial Clock Output for SPI Mode
UART Receive Data/SPI Data Input
3
TX/SDO
UART Transmit Data/SPI Data Output
4
CS
Chip Select for SPI Mode (active trailing edge)
5
CAL
Calibration ON/OFF Input (active trailing edge)
6
+5VDC*
7
GND
Power and Signal Ground
8
+V*
Unregulated Power Input (+6 to +15 VDC)
+5 VDC Regulated Power Input
*Note: Use either pin 6 (+5VDC) or pin 8 (+V) to power the circuit board. Hold the board with pin header edge close to
you and pins pointing DOWN. Then PIN 1 is the left most pin.
CIRCUIT DESCRIPTION
The HMR3200/HMR3300 Digital Compass Solutions include all the basic sensors and electronics to provide a digital
indication of heading. The HMR3200 has all three axis of magnetic sensors on board, but allows the user to select
which pair of sensors for compassing (flat or upright). The HMR3300 uses all three magnetic sensors plus includes
an accelerometer to provide tilt (pitch and roll) sensing relative to the board’s horizontal (flat) position.
The HMR3200/HMR3300 circuit starts with Honeywell HMC1021 and HMC1022 single and two-axis magnetic
sensors providing X, Y, and Z axis magnetic sensing of the earth’s field. These sensors are supplied power by a
constant current source to maintain best accuracy over temperature. The sensor output voltages and constant
current sensor supply voltage are provided to multiplexed Analog to Digital Converter (ADC) integrated circuit. A
microcontroller integrated circuit periodically queries the multiplexed ADC and performs the offset corrections and
computes the heading. This microcontroller also performs the external serial data interface and other housekeeping
functions such as the calibration routine. An onboard EEPROM integrated circuit is employed to retain necessary
data variables for best performance.
For the HMR3300, an additional pair of data inputs from the r2g accelerometer is received by the microcontroller.
These tilt inputs (pitch and roll) are added to sensor data inputs to form a complete data set for a three dimensional
computation of heading.
The power supply for the HMR3200/HMR3300 circuit is regulated +5 volt design allowing the user to directly provide
the regulated supply voltage or a +6 to +15 volt unregulated supply voltage. If the unregulated supply voltage is
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HMR3200/HMR3300
SENSOR PRODUCTS
provided, then the linear voltage regulator integrated circuit drops the excess supply voltage to a stable +5 volts. The
power supply is a dual ground (analog and digital) system to control internal noise and maximize measurment
accuracy.
PHYSICAL CHARACTERISTICS
The circuit board for the HMR3200/HMR3300 Digital Compassing Solutions is approximately 1.45 by 1 inches. An 8Pin header protrudes down on one edge of the board for the user interface or the demo board. The header pins
extend 5/16” below the board plane with the bottom-side mounted magnetic sensor integrated circuits (HMC1021
and HMC1022) extending 3/16” below the board plane. Components on the top-side have a maximum height of 1/8”.
Figure 1 shows a typical circuit board with dimensions.
1.45”
0.15”
8
7
6
.037”
5
4
1.00”
8-PIN
HEADER
(0.1” SPACING)
3
2
.037”
1
.094”
REF PINS
(2)
1.22”
Figure 1
Application Notes
UART COMMUNICATION PROTOCOL
HMR3200/HMR3300 modules communicate through ASCII characters. The data bit format is 1 Start, 8 Data, 1
Stop, and No parity bits. Asynchronous communication has the complete menu of commands.
OPERATIONAL COMMANDS
Syntax: *X<cr><lf>
Sends command for an operational mode change
Heading Output Command
*H<cr><lf>
Selects the Heading output mode (factory set default). This configuration is saved in non-volatile memory.
Format: Heading, Pitch, Roll (Heading Only for HMR3200) in degrees
Eg: 235.6,-0.3,2.8 (HMR3300)
Eg: 127.5 (HMR3200)
Magnetometer Output Command
*M<cr><lf>
Selects the magnetometer output mode. This configuration is saved in non-volatile memory.
Format: MagX, MagY, MagZ in counts
Eg: 1256,-234,1894
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HMR3200/HMR3300
SENSOR PRODUCTS
Compass Orientation (HMR3200 only)
*L<cr><lf>
Heading calculation is done assuming the compass is level.
*U<cr><lf>
Heading calculation is done assuming the compass is upright (connector end down).
These orientation commands are saved in non-volatile memory.
Starting and Stopping Data Output
*S<cr><lf>
The data output will toggle between Start and Stop each time this command is issued (factory set default is
Start, first Start/Stop command will stop data output).
Query
*Q<cr><lf>
Query for an output in the currently selected mode (Mag/Head). Allowed only in Stop data mode.
Roll Axis Re-Zero
*O<cr><lf>
Allows the user to zero the roll output. This command should only be issued when the roll axis is leveled
(r0.3°).
Pitch Axis Re-Zero
*P<cr><lf>
Allows the user to zero the pitch output. This command should only be used when the pitch axis is leveled
(r0.3°).
Averaged Output
*A<cr><lf>
Same result as the query command except that the data is the result of an averaging of the last 20 readings.
Allowed only in Stop data mode.
Split Filter Toggle
*F<cr><lf>
Toggles the split filter bit. The parameter setting is saved in the EEPROM immediately. Requires power
cycling or a reset command to activate.
Reset
*R<cr><lf>
Resets compass to power-up condition.
User Calibration
*C<cr><lf>
Command to be issued to enter and exit the calibration mode.
Once in the calibration mode, the device will send magnetometer data appended by a “C” character to indicate the
Calibration Mode operation.
Eg. 123,834,1489,C
During the calibration procedure, the compass and the platform to which the compass is attached is rotated at a
reasonably steady speed through 360 degrees. This process should at least take one minute for best accuracy. In
case of HMR3200, the rotation should be in the horizontal flat plane. For HMR3300, the rotation should include as
much pitch and roll orientations possible. At the completion of the rotations, issue another *C<cr><lf> to exit the
calibration mode.
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HMR3200/HMR3300
SENSOR PRODUCTS
CONFIGURATION COMMANDS
Syntax: #Dev=rxxxx<cr><lf> Sets parameter value
#Dev?<cr><lf>
Queries for the parameter value
Variation Input (Declination Angle Correction)
#Var=rnnnn<cr><lf> where the variation is r nnn.n degrees
Sets the angle between magnetic north and geographic north.
Eg: #Var=-203<cr><lf> sets the declination angle to –20.3 degrees.
Eg: #Var=?<cr><lf>returns the declination angle; –20.3
Deviation Input (Platform Angle Correction)
#Dev=rnnnn<cr><lf> where the angle is r nnn.n degrees
Sets or returns the angle between compass forward direction and that of the mounting platform.
Eg: #Dev=23<cr><lf> sets the deviation angle to +2.3 degrees.
Eg: #Dev=?<cr><lf>returns the deviation angle; +2.3
User Magnetic offset values (X, Y and Z)
#Xof, #Yof, #Zof
Sets or returns the user offset values for each magnetic axis.
Eg: #Xof=+47<cr><lf> sets the x offset value to +47.
Eg: #Xof=?<cr><lf> returns the x offset value; +47.
Baud Rate
#Bau
Sets the compass baud rate. 19200, 9600, 4800 and 2400 are the only allowed values. Baud rate can not
be queried.
System Filter
#SFL
Sets and reads the system IIR filter setting. When the Split Filter bit is cleared, this parameter value will
become the default value for Magnetic and Tilt Filters. When the Split Filter bit is set, SFL parameter setting
will control the Tilt filter value only. The parameter input is saved in the EEPROM immediately. Requires
power cycling or a Reset command (*R) to become effective. The setting of the Split Filter bit can be queried
via the #CON? command.
Eg: #SFL=3<cr><lf> Sets the system filter value of 3.
Magnetic Filter
#MFL
The MFL command sets and reads the Magnetic Filter setting. When the Split Filter bit is cleared, this
parameter value will default to the value of SFL, the system filter. When the Split Filter bit is set, MFL
parameter setting will control the Magnetic Filter value. The parameter input is saved in the EEPROM
immediately. Requires power cycling or a Reset command (*R) to become effective.
Configuration
#CON?
This command queries for the configuration status of the compass module. The output of the configuration
value is in decimal representation (in ASCII format) of which the 16-bit binary pattern is defined below.
bit 15
N/A
bit 14
N/A
bit 13
N/A
bit 12
N/A
bit 11
N/A
bit 10
SplitFilter
bit 9
Alarm
bit 8
Warn
bit 7
N/A
bit 6
N/A
bit 5
1
bit 4
N/A
bit 3
H Out
bit 2
N/A
bit 1
Mag Out
bit 0
N/A
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HMR3200/HMR3300
SENSOR PRODUCTS
Parameter
Name
Mag Out
H Out
Warn
Bit Value
Reported
1
1
1
Effect
Magnetic Sensor Output Sentence selected
Heading Output Sentence selected
Device temperature has fallen below -10 C during this session of
operation.
Alarm
1
Device temperature has fallen below -20 C during this session of
operation.
SplitFilter
1
Independent Filter values for Magnetic and Tilt are used
Eg: #CON? Returns a response of #D=1028<cr><lf> meaning independent filters used for magnetic and tilt
data (bit 10 set) and the compass module is sending heading data (bit 3 set).
COMMAND RESPONSES
These are compass module generated responses to commands issued by the host processor. These responses
follow in format to the commands issued.
#Dxxx<cr><lf>
Returns data requested.
#I<cr><lf>
Invalid command response. Response to any invalid command.
SPI INTERFACE
SPI operating Mode is as follows:
SCK idles low
Data Output after falling edge of SCK
Data sampled before rising edge of SCK
(MODE CKP=0, CKE=0)
Synchronous Communication Protocol
The HMR3200/HMR3300 module controls the synchronous clock (SCK) and synchronous data output (SDO) pins
and the host controller controls synchronous data input (SDI) and chip select (CS) pins. The host controller shall
lower the HMR module’s CS pin for at least 20 microseconds to initiate the SPI communication. In response the HMR
module will send the ASCII bit pattern for 's', and the host shall transmit a valid command character simultaneously.
The HMR module will evaluate the command character received from the host controller and send the appropriate
data if the command is recognized and valid. After transmitting the required data, the HMR module will end the SPI
session. If the command is invalid or was not recognized, then the HMR module will transmit ASCII bit pattern for 'e'
and end the SPI session.
SPI Commands
Heading Output: In response to an ASCII H or h command, the HMR3200/HMR3300 shall send two bytes of data.
The MSByte is transmitted first. These two bytes represent the integer value equal to 10*Heading. The MSbit is
transmitted first for each byte. SCK shall be high for 16, and low for 22 microseconds, respectively. There is a 50
microsecond delay between consecutive bytes transmitted.
Command Character
H or h
Action
Sends heading data
SPI Data Output
0000 to 3599
Parameter Value
Heading: 000.0 to 359.9
DATA REPRESENTATION
Heading Output: In response to an H or h command, HMR3200/HMR3300 module shall send two bytes of data. The
MSByte is transmitted first. These two bytes represent the integer value equal to 10*Heading. The MSbit is
transmitted first for each byte.
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HMR3200/HMR3300
SENSOR PRODUCTS
SPI TIMING
The SCK shall be high for 16, and low for 22 microseconds, respectively. There is a 50 microsecond delay between
consecutive bytes transmitted.
CS
Th ~ 16Psec
SCK
Tl ~ 22Psec
SDO
MS bit
SDI
SPI Timing Diagram
LS Byte
MS Byte
Tb = 50Psec
SPI Heading Output
Demonstration PCB Module Kit
The HMR3200 (HMR3300) Demo Module includes additional hardware and Windows software to form a
development kit for electronic compassing. This kit includes the HMR3200 (HMR3300) Printed Circuit Board (PCB)
module, an RS-232 motherboard with D9 serial port connector, serial port cable with attached AC adapter power
supply, interface software, and documentation.
Ordering Information
Ordering Number
Product
HMR3200
HMR3200-Demo-232
PCB Module Only
PCB Module with Development Kit
HMR3300
HMR3300-D00-232
HMR3300-Demo-232
PCB Module Only
PCB Module and RS-232 Motherboard
PCB Module with Development Kit
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
900266 02-03 Rev. D
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HMR4001
SENSOR PRODUCTS
Advance Information
LINEAR POSITION SENSOR MODULE
Features
·
·
·
·
·
·
·
·
0-10 mm Magnetic Travel (Magnet Dependent)
Continuous PWM and Analog Voltage Outputs
0.2mm Accuracy (Magnet Dependent)
0.05mm Repeatability
-40° to +85°C Operating Temperature Range
1%/100°C Temperature Effect
Small PCB Package
6 to 20 volt DC Single Supply Required
General Description
The Honeywell HMR4001 is a high-resolution single
sensor module capable of measuring linear or angular
position. Advantages include high sensitivity so lower
cost magnets such as alnico or ceramic can be used,
insensitivity to shock and vibration, and ability to
withstand large variations in the gap between the
sensor and the magnet.
The HMR4001 is manufactured with Honeywell's
HMC1512 Magnetic Displacement Sensor IC, which
provides better performance than Hall Effect devices
and only needs a magnetic field source greater than 80
gauss. Dual frequency PWM and analog outputs plus a
sleep mode function are included on board
APPLICATIONS
Block Diagram
· Linear Displacement
· Shaft Position
· Angular Displacement
·
Proximity Detection
Web Site:
Email:
www.magneticsensors.com
[email protected]
2001 HMR4001
Published Jun 2001
Page 1
Honeywell
Solid State Electronics Center
12001 State Highway 55
Plymouth, Minnesota 55441-4799
1-800-323-8295
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HMR4001
SENSOR PRODUCTS
Advance Information
SPECIFICATIONS
Characteristics
Conditions
HMR4001
Min
Typ
Max
Units
Linear Position
Range
> 80 gauss at sensor
10
mm
Accuracy
> 80 gauss at sensor
0.2
mm
Repeatability
> 80 gauss at sensor
0.05
mm
Range
> 80 gauss at sensor
90
deg
Accuracy
> 80 gauss at sensor
0.1
deg
Repeatability
> 80 gauss at sensor
0.07
deg
Angular Position
Magnetic Field
Strength
Repeatability <0.03% FS
80
-
-
gauss
Voltage
Unregulated
6
-
20
volts DC
Current
Active Mode - SLEEP pin = 5V (or open)
7
mA
Supply
Sleep Mode - SLEEP pin = 0V
<2
mA
FS = 5V (or open)
350
Hz
FS = 0V
250
Hz
Electrical
PWM Output
Frequency
Frequency
Ambient Temperature (+23°C)
+/-8
-
-
%
“1” Level Duty Cycle
1
-
99
%
“1” Level at any Position
4.5
-
5.5
Volts
Accuracy
PWM Range
PWM
Amplitude
pk-pk
Analog Output
Range
Ambient Temperature (+23°C)
-
4.0
-
volts
Physical
Dimensions
circuit board only
15x48.5x12
mm
Weight
circuit board only
5
grams
Environment
Temperature
Operating
-40
-
+85
°C
Storage
-55
-
+125
°C
Web Site:
Email:
www.magneticsensors.com
[email protected]
2001 HMR4001
Published Jun 2001
Page 2
Honeywell
Solid State Electronics Center
12001 State Highway 55
Plymouth, Minnesota 55441-4799
1-800-323-8295
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HMR4001
SENSOR PRODUCTS
Advance Information
Pin Configuration
Pin
Function
Description
VA
ANALOG OUTPUT
PW
PWM OUTPUT
FS
FREQUENCY SELECT INPUT
V+
SL
POWER SUPPLY INPUT
SLEEP/WAKE INPUT
GD
GROUND
Analog Version of the PWM Output Using a Low Pass
Filter.
Digital Signal With the “1” Level Equivalent to the
Position of the Magnet. Period at 250 or 350 Hz.
Selects the Pulse Width Modulation Frequency:
1=350Hz, 0=250Hz (onboard pullup)
Power Supply Input of +6 to +20 Volts DC.
Selects the Wake or Sleep Mode: 1=Wake, 0=Sleep.
Onboard Pullup Resistor to Keep Board in Wake Mode.
Ground Reference for Supply and I/O
Circuit Board Layout
Application Notes
Very high precision position measurements using weak magnetic fields should note the influence of the earth’s
magnetic field (~ 0.6 gauss) bias on the sensed magnet position.
The center-line of HMC1512 sensor integrated circuit U1 is determined to be midpoint (50% Pulse Width, 2.5v
Analog) for position sensing.
Only one of the two sensor bridges in the HMC1512 is used for sensing the external magnetic field. The other
magneto-resistive bridge network is used as temperature compensation network to retain precise positioning over a
broad temperature range. Thus the single bridge provides its linearity over a 90° sweep (+/- 45°) as opposed to when
both HMC1512 bridges are working together for a 180° (+/- 90°) sweep.
For best performance, a magnetic field of at least 80 gauss measured at the sensor location should be maintained. A
simple dipole magnet usually has the strongest field near its poles, and the field decreases with the distance. For
example: An AlNiCo cylindrical magnet with a 0.25” diameter has field strength of 700 gauss at its surface. With a
0.25” gap between the sensor and the magnet, the field at the sensor is about 170 gauss. This is enough field
strength to maintain the sensor in the saturation condition for most applications.
Web Site:
Email:
www.magneticsensors.com
[email protected]
2001 HMR4001
Published Jun 2001
Page 3
Honeywell
Solid State Electronics Center
12001 State Highway 55
Plymouth, Minnesota 55441-4799
1-800-323-8295
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HMR4001
SENSOR PRODUCTS
Advance Information
Moving Shaft
N
S
Magnet
HMC1512 Sensor
Demonstration PCB Module
The HMR4001 Demo Module includes an attached magnet and slide assembly for evaluating the performance of the
module.
Ordering Information
Ordering Number
HMR4001-D00 -DEMO
HMR4001-D00
Product
PCB Module with Attached Magnet Assembly
PCB Module Only
Honeywell reserves the right to make changes to improve reliability, function or design. Honeywell does not assume
any liability arising out of the application or use of any product or circuit described herein; neither does it convey any
license under its patent rights nor the rights of others.
Web Site:
Email:
www.magneticsensors.com
[email protected]
2001 HMR4001
Published Jun 2001
Page 4
Honeywell
Solid State Electronics Center
12001 State Highway 55
Plymouth, Minnesota 55441-4799
1-800-323-8295
Courtesy of Steven Engineering, Inc.-230 Ryan Way, South San Francisco, CA 94080-6370-Main Office: (650) 588-9200-Outside Local Area: (800) 258-9200-www.stevenengineering.com
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