“SMC-40” STEPPER MOTOR CONTROL I.C. AND PERHIPHERAL

“SMC-40” STEPPER MOTOR CONTROL I.C. AND PERHIPHERAL
SMC-40 Hardware - Revision Date: 03/29/06
“SMC-40”
STEPPER MOTOR CONTROL I.C.
AND PERHIPHERAL DEVICE (SMO-40, SME-40)
HARDWARE MANUAL
SMC-40 Hardware - Revision Date: 03/29/06
SMC-40
TABLE OF CONTENTS
Product Overview
SMC-40 Features ................................................................................................................................. 1
Minimum Circuit Requirements ............................................................................................................ 1
Power-up Program ............................................................................................................................... 2
Party Line.............................................................................................................................................. 2
Trip Point .............................................................................................................................................. 2
Bi-directional Ramping ......................................................................................................................... 2
Program/Constant Storage................................................................................................................... 2
Go Input ................................................................................................................................................ 2
Jog Capability ....................................................................................................................................... 2
Pin Description ..................................................................................................................................... 3
Support Hardware
Design Considerations ......................................................................................................................... 7
Clock..................................................................................................................................................... 7
Hardware Reset.................................................................................................................................... 7
NV Memory........................................................................................................................................... 7
I/O Ports................................................................................................................................................ 7
Serial Interface ..................................................................................................................................... 8
Specifications
DC Characteristics................................................................................................................................ 9
AC Characteristics................................................................................................................................ 9
Non-Volatile Memory Operation ........................................................................................................... 9
TSSOP28 Package Specifications ..................................................................................................... 10
PLCC28 Package Specifications........................................................................................................ 11
Peripheral Devices
Overview............................................................................................................................................. 12
Design Considerations ....................................................................................................................... 12
Analog Input Overview (SMO-40) ...................................................................................................... 13
SMO-40 Pin Description ..................................................................................................................... 14
Encoder Feedback (SME-40)............................................................................................................. 15
Block Diagram .................................................................................................................................... 15
Operation ............................................................................................................................................ 16
SME-40 Pin Description ..................................................................................................................... 17
Peripheral Device Interconnect Diagram ........................................................................................... 18
SMO-40, SME-40 Specifications........................................................................................................ 19
SO20 Package Specifications ............................................................................................................ 19
i
ADVANCED MICRO SYSTEMS, INC.
ii
TABLE OF CONTENTS
SMC-40
PRODUCT OVERVIEW
SMC-40 Features
The SMC-40 is a microcomputer chip capable of indexing stepping motors. This advanced controller
is fast, low power and comes in a small package size.
• NO crystal oscillator required
• NO reset circuit required
• Self contained non volatile memory
• Maximum step rates above 65,000 SPS
• Non-volatile memory for stand alone operation
• Multiple axis control from a single COM port
• Limit and Home inputs
• Go and soft stop inputs
• Six user ports
• Moving/Driver Enable output
• Small 28 pin PLCC28 and TSSOP28 surface mount packages sizes
Available single chip (I2C) peripherals
• Additional NV (EEprom) memory
• Analog input processor
• Encoder feedback processor
• SIN-11 smart serial communication processor
Minimum Circuit Requirements
2
+5V
14
RS-232
TXD+
RS232 - RXD
TXDRXD+
RXD-
5
10
LimA
LimB
1
2
13
14
23
24
15
16
4
4
2
17
18
12
11
3
Port 1
Port 2
Port 3
Port 4
Port 5
Port 6
Led 1
Led 2
3.3V
19
25
RXD
TXD
Step
20
Dir
22
Mvg
27
Xstep
plcc28
Xdir
SDA
7
SCL
Dir.
To Power Driver
Enable optional
Enable
10
28
+5V
11
12
3.3k (2)
Peripherals:
Analog /shuttle processor SMO-40
Encoder feedback SME-40
2048 Bytes NV (EEPROM)
+5V
3.3k
Expansion to
more SMC-40's
Party Line
Step
SMC-40
PTYi/o
6
7
RS232 - TXD
75ALS180
9
GO
SS
Home
rst
User
Inputs
and
Outputs
3
26
5
GND
GND
RS-422
3.3V
21
Out
1
Vin
6
3
+5V
GND
Only a few components are necessary to create a complete single axis controller. All user inputs and
outputs are 3-5 volt logic and should be appropriately buffered.
+5V
Disable
Jumper
SMC-40 Minimum Circuit Requirements
Note: The SMC-40 is a derivative of the microprocessor used in Advanced Micro Systems IBC-400
control module. Thus, the IBC-400 is a low cost way to evaluate designs without the initial prototype
expense.
1
ADVANCED MICRO SYSTEMS, INC.
PRODUCT OVERVIEW
Power-up Program
On reset a special non-volatile (NV) memory address (192) is tested for executable instructions. The
program can include home sequences or other special operations.
Party Line
The SMC-40 has the ability to be operated in a multiple axis Party Line mode. The architecture is
analogous to a mini network. This parallel mode permits full duplex communications with all SMC-40
devices. Listening simultaneously to incoming commands, it is a much faster communication protocol
in systems with many axes. Signals to control line driver “output enable”(pin 4) are provided when the
requested axis wakes up.
Trip Point
The Trip Point is a programmable position that allows pre-defined operations to be executed when the
motor position matches the Trip Point value. A typical application may be to turn on a valve when a
desired position is passed.
Bi-directional Ramping
The SMC-40 can ramp either up or down to the specified constant velocities. The ramp slope may be
altered prior to changing speeds. A Trip Point can be used to trigger velocity changes. The SMC-40
also supports independent deceleration ramping.
Program/Constant Storage
The SMC-40 includes 512 bytes of nonvolatile memory (EEPROM) and 512 bytes of RAM. Programs
are written to and executed from the high speed RAM. Store commands copy the RAM image into the
EEPROM. During power up reset the “shadow” EEPROM image (512 bytes) is copied into the RAM.
These memories also retain all parameters and modes
Provision is made to implement up to 2,048 bytes of external NV memory. The low cost NV
(EEPROM) memory is connected via a two wire (I2C) interface. Direct read and write commands
allow host use of the memory.
Go Input
A Go input is provided that allows execution of user sequences that have been preloaded into the NV
memory. A simple pulse will start the sequence any time. Use of a terminal, host, etc., is not required
thus allowing low cost, stand-alone operation.
Jog Capability
The SMO-40 is an analog/digital converter, offered by AMS that provides analog joystick interface.
This peripheral processor implements A to D and D to A converters to digitize voltage input. The
input can be either uni-directional (single direction) or bi-directional.
Once digitized, the generated motor speed is managed by software. Parameters include start and
maximum speed. A dead zone parameter prevents drift and hysteresis to reduce hunting. Acceleration
supervision prevents motor stall that could occur with abrupt input changes.
In addition to analog input the OSC-40 provides step/direction or A/B quadrature inputs. The
quadrature inputs can accept signals from standard encoders, converting them to a step/direction
motion. A most useful application is a “shuttle follower” control. A panel mounted rotary encoder
permits position adjustment, with speed and position following the operator’s rotation.
This single chip system is interfaced using Xstep/Xdirection inputs and I2C bus communications.
2
SMC-40
PRODUCT OVERVIEW
Pin Description
28 PIN TSSOP
5
6
7
8
9
10
11
25
24
23
22
21
20
19
Lim B
Port6
Port5
Dir Out
3.3V (Vdd)
Step out
Lim A
Party En
ENCODER
ANALOG
NV RAM
Port 1
Port 2
Go in
Party en
Home
RST
GND
X1
X2
Xstep
SDA
SCL
Port 3
Po rt 4
XDir
MVG
Stop
Lim B
Port6
Port5
Dir
3.3V
Step
Lim A
TXD
RXD
LED2
LED1
POWER DRIVER
MOTOR
Party En
RS-232
OR 422
SCL
Port 3
Port 4
Led 1
Led 2
RXD
TXD
12
13
14
15
16
17
18
Home
Reserved
GND
NC
NC
Xstep
SDA
4
3
2
1
28
27
26
Party
Go
Port2
Port1
Xdir
Mvg
Stop
28 PIN PLCC
Note: Signal pin numbers are the same for either package.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Name
Port1
Port 2
GO
Party
Home
Reset
GND
Xtal1
Xtal2
Xstep
SDA
SCL
Port 3
Port 4
Port 5
Port 6
RXD
TXD
Lim A
Step
3.3V
Dir
Led 1
Led 2
Lim B
Stop
MVG
Xdir
Function
General purpose input or output Port
General purpose input or output Port
Input starts user program at address zero
Output enables RS-422 bus driver
Input used for home routine, can also be read as input
Input – pull to high
Power supply and logic common
Not currently used (oscillator is built in)
Not currently used (oscillator is built in)
External step pulse input – analog joystick, encoder
I2C bus clock for memory expand or other options – requires pull-up
I2C bus data for memory expand or other options – requires pull-up
General purpose input or output port
General purpose input or output port
General purpose input or output port
General purpose input or output port
Serial data input – from host computer
Serial data output – to host computer
Travel Limit input, invertible
Output to driver – pulse (65K SPS or square wave 32K SPS
Power supply input – 25Ma maximum
Direction control to driver
Optional activity LED
Optional activity LED
Travel limit input, invertible
Input stops executing user program
Output indicates moving, can be ‘off’ delayed, invertible
External direction input, used with Xstep (pin 10) input
3
ADVANCED MICRO SYSTEMS, INC.
PRODUCT OVERVIEW
While the SMC-40 operates from a 3.3-volt power supply, all specified inputs and outputs are 5 volt
tolerant. You should use pull-up resistors for interface to standard 5-volt logic. Because any pin could
be configured as an output or input, all input pins (especially those designated as I/O) should be
interfaced with open collector/drain with pull-up resistors to avoid possible damage.
Signals configured as outputs have an absolute maximum rating of 20 mA (sinking). The
recommended maximum output sink current should be designed to be 2 mA or less. While the outputs
have weak pull-up resistors, external pull-up resistors may be necessary. PCB lead length should be as
short as possible, preferably less than 2 inches. Failure to use buffering to and from connectors can
expose the SMC-40 IC to damage.
Note: The following descriptions assume that all used signals use pull-up (to +5 volt) resistors.
Unused inputs should be tied together and then pulled up to 5v volts for noise immunity.
User Ports (pins 1, 2, 13, 14, 15, 16)
Ports 1 through port 6 can be used as either outputs or inputs. The hardware (buffer) design will define
the type. The off condition is defined as a high (5-volt) level. Some or all of the ports can be designed
as outputs as the application requires. Low numbered ports are selected as inputs because loop and
branch commands employ these as inputs. The ‘A’ command is used to set, reset or read these inputs.
Go, Stop Inputs (pins 3, 26)
These inputs are useful for starting and stopping previously stored “program” sequences in stand-alone
applications. Program execution can be initiated in three ways:
1. The ‘G’ (Go) command
2. Auto start on power up (or reset)
3. An input (low going) pulse to pin 3
The Go input pulse width should be a minimum of 10 mS. The program will start execution at memory
location 0 (zero). If the program does not loop (run continuous) the Go input is sampled and if it is still
low, execution will repeat.
The Stop (Soft Stop) will terminate motion and program execution, returning the SMC-40 to an idle
state. If the Go input is active, a new start is triggered.
Party Output (pin 4)
This output is used to enable a differential RS-485 line driver in Party Line designs. Party Line
operation permits a number of distributed controllers to operate in a 4-wire, full duplex RS-422
architecture. The output is high after reset, enabling the driver. On entry into Party Line mode, pin 4
will go low, disabling the line driver when not communicating.
Home Input (pin 5)
The home input is used during execution of the “find home” command, commonly used after power up
or to re-zero a position. It is possible to read this as a general purpose input if this type of homing is
not required.
Reset (pin 6)
The SMC-40 has a built in reset at power up. There is no need for external components. If the reset
signal is held low when power is applied, the processor will be held in a reset condition. This can be
used to disable an axis in a multiple SMC-40 design where disabling other controllers allows naming
of one single controller.
4
SMC-40
PRODUCT OVERVIEW
XSTEP, XDIR) Input (pins 10, 28)
These inputs allow stepping from external sources. Enabled under control of software, these are used
with the SMO-40 analog joystick controller IC and SME-40 encoder controller IC.
SDA, SCL (pins 11,12)
This is an I2C bus interface. The 2 wire Inter-Integrated Circuit provides a small network for slave
components including EE Proms (NV memory), and slave processors such as the SMO-40. Both these
signals must be pulled up with 3.3k resistors to 5 volts. As of this time, external memory expansion to
2048 bytes is available.
RXD Input (pin 17)
This signal receives data (9600 baud) from a host computer. ASCII command/data is used to execute
commands. To avoid errors, echoed character-by-character handshake must be performed. Software
operating with DOS or Windows98 can be done, while Windows 2000, ME, and XP can be difficult.
In all cases a SIN-11 serial adapter is recommended. It performs all the necessary functions and
simplifies programming.
TXD Output (pin 18)
This output signal transmits serial data to the host via the line driver. Functions include handshake and
reading data, status and position. In Party Line designs, the line driver is enabled from the party enable
signal (pin 4).
Limit Inputs (pins 19, 25)
Two limit inputs (LIM A, LIM B) are sampled on each step of motion. Depending on direction, each
input will prevent motion in that direction, for instance LIM A will prevent CW motion while
permitting CCW movement. Conversely, LIM B will stop motion in the opposite direction. Actual
definition of direction depends on a number of factors including motor wiring, driver type, mechanics,
etc.
By default a low input voltage will activate a limit, however, the l (lower case L) command can be
used to invert the polarity. In this case both limits will have to be held at a low (0 volt) to permit
motion.
Step, Direction Output (pins 20,22)
These are the control signals for your driver. The step pulse is low going, about 10 uS wide. For
drivers that do not respond, the l (lower case L) command will insert a virtual flip-flop on the output,
producing a square wave. This also has the effect of dividing the step rate by 2, reducing the maximum
step per second to about 32,000.
LED Outputs (pins 23,24)
Connect a bi-color LED between these two pins with 1k pull-up resistors. These are useful for some
status displays.
MVG Output (pin 27)
The moving signal is activated when motion is generated (output steps). This signal (low when moving
by default) is turned off after stepping stops. This signal may be used to control motor driver enable or
current setback. Often it is desirable to allow a “settling” time before the winding current is removed
This programmable delay time is specified using the ‘E’ command. The l (lower case L) command can
be used to invert the output polarity.
Power
GND (pin 7) is the logic power common.
VDD (pin 21) is the controller logic supply and is a regulated 3.3 Vdc.
5
ADVANCED MICRO SYSTEMS, INC.
PRODUCT OVERVIEW
Commonly available low-voltage dropout (LDO) regulators will operate from the standard 5volt logic
power.
6
SMC-40
SUPPORT HARDWARE
Design Considerations
The SMC-40 requires a minimum of external components for operation. Good design practice with
CMOS devices, such as the SMC-40, desires buffering or isolation of all input and output signals that
have to travel more then a couple of inches, especially off of a circuit board and in noisy
environments.
Simple local buffering may be achieved through use of logic buffers such as 74HC04’s, 7406’s,
7407’s or other low cost devices. Noisy environments may dictate use of optical isolation. The low
input sink requirements (800ua. max.) of the SMC-40 permit most isolators to directly drive the inputs.
Outputs should be buffered to increase L.E.D. drive current.
An excellent input design uses the LM-339 quad comparator. It has open collector and withstands 36
volts on the inputs. Reference the IBC-400 schematic.
Clock
The SMC-40 has a built in clock. No external hardware is required.
Hardware Reset
The SMC-40 has a built in reset. No external hardware is required.
NV Memory
The SMC-40 contains 512 Bytes of NV (EEprom) memory. The relatively slow NV memory image is
copied into a 512 byte RAM during reset initialization. The NV memory retains all stored parameters
and user program commands.
If a user program is extensive, this internal memory may not be sufficient. External NV memory may
be attached via the SDA/SCL lines. Currently 2048 bytes of EEPROM is supported. The external
memory has an access time of about 1mS per byte. Suppliers of suitable NV memory products include:
Ramtron (FM24C16)
Xicore (X24C16)
Catalyst (CAT24WC16)
I/O Ports
Six general-purpose I/O ports are available on the SMC-40. To the SMC-40 they all look the same.
They can be written to and be read back. In order to be used as inputs, the open drain portion of the
output must be off, as in the power up condition.
An SMC-40 command that contains zeros in the binary mapped value will also set the desired ports
“off.” The command “A 0” will turn all the outputs to the off (all 1’s) or open condition. Usually
external hardware defines the port direction.
Most Advanced Micro Systems products buffer ports 1, 2 and 3 as inputs, port 4 as input and output,
and port 5 and 6 as outputs. Resistors should be inserted on “inputs” driven by totem-pole drivers to
prevent excessive current should the port be turned on as an output conflict.
The SMC-40 can view all ports as inputs and outputs, restricted by contention with external hardware.
Any “output” port can be modified, then subsequently used in conjunction with the L, G2048, or A129
(read) commands.
7
ADVANCED MICRO SYSTEMS, INC.
SUPPORT HARDWARE
Serial Interface
Two-signal (TXD and RXD) data lines with ASCII characters do all communication to an external
computer. The COM port interface must be used either to initialize and load sequences in the
beginning or to communicate to a permanent host computer. One IC line driver and receiver is used
per system (a system is defined as one or more axis located on a single PCB or in very close proximity
to one another).
Three 5-volt logic signals (TXD, RXD and PTY) are connected in parallel. The maximum
recommended number of axis is 15. Each axis must be named individually with a unique name
character.
The naming process is as follows:
1. With power off, install disable jumpers in all axis except the one to be named.
2. Apply power. The one enabled axis will operate in the “single” line mode.
3. Refer to the IBC-400 manual for naming and single axis functions.
This product is equivalent to the device used in the AMS product- IBC-400. Please refer to the IBC400 manual for all software procedures and command usage, including single axis and party line
operations.
8
SMC-40
SPECIFICATIONS
DC Characteristics
Parameter
Idd
Vdd
Vin max
Vil
Iil
Vith
Iih
Vol
Voh
I/O Max
Description
Power supply current
Logic supply voltage
Absolute maximum
Input low Schmitt threshold
Input low current
Input high Schmitt threshold
Input high current
Output low voltage
Output high voltage
Output current per I/O pin
Condition
Min
Any pin
-.5
0.73
Typ
15
3.3
Max
25
3.6
5.5
1.32
Vin=0.4V
1.98
Vi=vcc-1.5
Iol=3.2ma
Ext pull-up
-50
2.31
500
0.3
5.5
20
Units
Ma
V
V
µa
V
µa
V
V
Ma
AC Characteristics
Parameter
Baud Rate
Step Rate
Step Pulse Width
Swl
Description
8 bits, no parity, 1 start, 1 stop
Range (internal clock)
Output to driver
Limit/home switch response
Min.
57
5
2
Typ
9600
Max.
Units
65000
7
SPS
µs
Step Clk
Operating Temperature: -40o to +85o C
Non-Volatile Memory Operation
Instruction
Fetch and execute cycle
Save parameters
Condition
Loop
Store
Typ
1.7
63
Units
Ms
Ms
9
ADVANCED MICRO SYSTEMS, INC.
TSSOP28 Package Specifications
10
SPECIFICATIONS
SMC-40
SPECIFICATIONS
PLCC28 Package Specifications
PLCC28: plastic leaded chip carrier; 28 leads
eE
eE
y
X
A
19
25
18
26
bp
b1
ZE
w M
28
1
HE
E
pin 1 index
e
A
A4 A 1
12
4
b
k1
(A 3)
k
5
11
Lp
v M A
ZD
e
detail X
D
B
HD
v M B
0
5
10 mm
scale
DIMENSIONS (millimetre dimensions are derived from the original inch dimensions)
k
k1
max.
Lp
v
w
y
1.22
1.07
0.51
1.44
1.02
0.18
0.18
0.10
Z D(1) Z E (1) b
max. max.
UNIT
A
A1
min.
A3
A4
max.
bp
b1
mm
4.57
4.19
0.51
0.25
3.05
0.53
0.33
0.81
0.66
0.12
0.021 0.032 0.456 0.456
0.430 0.430 0.495 0.495 0.048
0.057
0.020
0.05
0.007 0.007 0.004 0.085 0.085
0.390 0.390 0.485 0.485 0.042
0.040
0.013 0.026 0.450 0.450
inches
0.180
0.165 0.020
0.01
D (1)
E (1)
e
eD
eE
HD
HE
11.58 11.58
10.92 10.92 12.57 12.57
1.27
11.43 11.43
9.91 9.91 12.32 12.32
2.16
2.16
45 o
Note
1. Plastic or metal protrusions of 0.01 inches maximum per side are not included.
OUTLINE
VERSION
SOT261-2
REFERENCES
IEC
JEDEC
EIAJ
EUROPEAN
PROJECTION
ISSUE DATE
92-11-17
95-02-25
11
ADVANCED MICRO SYSTEMS, INC.
PERIPHERAL DEVICES
Overview.
Note: These peripheral products are the core devices used in the AMS model “IBC-400” step motor
controller. Please refer to the IBC-400 manual for all software procedures and command usage,
including single axis and party line operations.
Three peripheral devices, the SMO-40, SME-40 and NV2048, are available to enhance the
functionality of the SMC-40 controller. These “slave” devices communicate over the standard I2C wire
bus. Like the SMC-40, these products stand-alone and do not require external crystals, memory or
reset circuitry.
Encoder
Motor
Decoder
Counter
Joy
Stick
SMC-40
Control Center
24 bits
SMO-40
Analog
CPU
SME-40
Encoder
CPU
Step
and
Direction
NV2048
RAM
Ramp Generator
Limit, Home Inputs
Resolution, Speed
Input/Output Ports
RS-232
RS-422
Serial
Interface
2
I C BUS
Two of the devices are low power controllers powered by 5-volts and are supplied in a 20-pin (SO20)
small outline surface mount package.
-SMO-40 Analog “Joystick” Inter face- In addition to the analog input, remote step and
direction or quadrature A/B logic signal inputs are available.
-SME-40 Encoder Interface- Provides servo like position control and error detection.
The third device, NV2048, adds 248 bytes of serial EEPROM to expand program storage beyond the
512 bytes already contained in the SMC-40.
None of these devices are necessary for SMC-40 operation. The SMC-40 will detect and install these
devices at power-up reset. Simple interface to the SMC-40 “master” processor requires only four or
five connections.
Design Considerations
These devices require a minimum of external components for operation. Good design practice with
HMOS and CMOS devices, calls for buffering or isolation of all input and output signals that have to
travel more then a couple of inches, especially off of a circuit board and in noisy environments.
Simple buffering may be achieved through use of low cost comparators such as the tried and true
LM339 or equivalent. In addition to isolation, their inputs will withstand over 30 volts. These
comparators have open collector outputs and may require external pull-up resistors.
Noisy environments may dictate use of optical isolation. The low input sink requirements (800ua.
max.) allow most isolators to directly drive the inputs. Outputs should be buffered to increase drive
current and noise isolation.
12
7/11/2008
SMC-40
PERIPHERAL DEVICES
Analog Input Overview (SMO-40)
The newest products from Advanced Micro Systems are available with analog input. This input is used
to generate a variable step rate frequency. The system is more than a simple voltage-to-frequency
design. Input voltage is digitized with an Analog to Digital converter, and then digitally processed.
The result is a stable, controlled step rate and direction function. A special processor, part number
SMO-40 is used to provide the analog conversion. The SMO-40 is a slave to the SMC-40,
communicating by a 4-wire buss.
Products with the “A” option (IBC-400A and mStep407-A) have this system implemented.
The analog “joystick” interface adds yet another dimension of motion control possibilities by
providing the capability of speed that is proportional to the input voltage. Features include:
• A digitized analog input
• A “dead-zone” that is applied before stepping starts
• Stepping that starts at a specified rate
• Speed, governed by an acceleration setting, increases as voltage increases
• Speed, governed by a deceleration setting, decreases as voltage decreases
• A maximum speed setting
• An auto-zero function that can remove any offset
• The Auto-mode function selects Uni-directional or bi-directional mode
• Two multi-turn potentiometers adjust range and gain
Probably the most advanced feature is the ability to constrain acceleration and deceleration rates. This
function helps prevent step motor stall conditions that can occur when the step rate is changed
abruptly. As the input voltage changes, the step rate is determined by a lookup table. The
acceleration/deceleration profile is governed using the same algorithm as the standard “index” function
used in the master CPU.
Joystick
5 Volts
Range
I2C
A-D
Gnd
2.5 Volts
D-A
Gnd
Select
step / direction
source
Step
Direction
TO
MASTER
CPU
ANALOG PROCESSOR
Analog Joystick Block Diagram
Caution- the input buffering op-amp’s are not necessary, but without them the processor input is
easily subject to damage.
13
ADVANCED MICRO SYSTEMS, INC.
PERIPHERAL DEVICES
Joystick Input -Accepts analog voltage and produces either uni-directional or bi-directional motion
control with the speed proportional to the input voltage. Input voltage range is either 0 to 5 volts (unidirectional) or 0 to 2.5 to 5 volts bi-directional, where 2.5 volts equals zero speed center. An analog
output is used for an “auto-zeroing” function.
Digital Inputs- These may be specified by mode command, as either step/direction or A/B inputs. The
step and direction mode permits motion from an external step pulse and direction source. In the A/B
mode it accepts two-phase input signals such as those produced by incremental encoders. Encoder
resolution is specified in line count (slots in encoder wheel) the SMO-40 multiplies this by 4, thus a
400 line encoder will produce 2000 step pulses per revolution.
These encoders (usually optical) are available in panel mount versions. It is useful to simply
implement a shuttle or position adjustment feature. The motor will “follow” the encoder rotation in
both speed and position. Speeds and position ratio are dependent on encoder counts (X4) per
revolution, motor steps per revolution, and any mechanical gearing.
SMO-40 Pin Description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Signal
Description
Xstep
Dac
Reset
GND
Step pulse to SMC-40
Pull-up to +5 volts
Power common
SDA
SCL
I2C communication with SMC-40
I2C communication with SMC-40
Xdir
Joy
VCC
Step and direction to SMC-40
Analog input 0-5 volts or 2.5 volts + 2.5 volts
+5 volt power input
Step/A
Dir/B
External step pulse (low going) or phase A of an encoder
External direction pulse (low going) or phase B of an encoder
Note:
1. Absolute maximum voltage +5.5 volts on any input.
2. All external inputs must be isolated with appropriate buffer circuitry, using LM339 comparators
is recommended.
3. Minimum setup times and pulse width 10uS.
14
7/11/2008
SMC-40
PERIPHERAL DEVICES
Encoder Feedback (SME-40)
The encoder feedback module is comprised of two essential components:
1. A 24 bit quadrature counter accepts the A-B quadrature encoder signals. After filtering and
decoding with a 4X decoder, a 24 bit binary bi-directional counter tracks the position. While
seldom encountered, clock rates to 25mHZ are possible. The count range is +8,388,607.
With a quality disc and properly phased encoder, this 4X signal will be accurate to better than 1/2
count. A 500-line encoder mounted to the rear of a stepper motor will generate 2,000 counts per
revolution.
2. SME-40 controller that performs encoder functions. Modes include
a. Stall detection – During indexes the encoder position is constantly sampled and tested for
progress in the desired direction. Should excessive lag be detected, the host CPU (SMC-40) is
notified. The SMC-40 will perform corrective action as defined by the settings.
b. Position maintenance – The encoder position is compared with the “target” position. If an
error is detected (the position error is greater than the “dead band”) then Xstep and Xdirection
signals are generated to correct the error.
Command and data exchanges are accomplished over the two-wire I2C bus.
In addition to the two channel inputs, index pulse homing is possible. A feature with the SME-40
includes provision for battery backup to prevent position loss and operation with almost any resolution
encoder. The encoder option (E) may co-exist with the analog option (A).
Features include:
• Use with 50-1024 line (CPR) encoders
• Monitor for stall condition during index
• Retry index “n” times upon stall detect
• Position maintenance mode with deadband
• Battery backup input to keep position registers
Block Diagram (SME-40)
Step/Dir Feedback
Stall Interrupt
Position
Encoder
Input
Correction Speed
Dead Band
Stall Monitor
Reference Position
Step/Dir In
Position Compare
Quadrature
Decoder
24 Bit Position
Counter
ENCODER PROCESSOR
15
ADVANCED MICRO SYSTEMS, INC.
PERIPHERAL DEVICES
Operation
The encoder system is composed of the following components:
1. Quadrature input that decodes encoder A-B signal to obtain 4X resolution. For instance, a 500
“line” encoder will produce 2,000 counts per revolution.
2. A 24 bit bi-directional counter that tracks incremental encoder position at count rates to 1
MHZ.
3. A Control Microprocessor (CPU) that provides stall detection, and re-position outside dead
zone control and math functions to convert encoder motion commands into step motor index
distance. The CPU communicates with the master (SMC-40) microcomputer via serial bus and
step and direction signals to maintain/monitor target position and encoder counter position.
The encoder CPU receives the parameter information: encoder resolution, microstep resolution,
deadband size, allowed lag, and hunt speeds. On receipt of an index command, the CPU calculates a
number for the “step index” and stall monitoring is started by loading the retry counter. The CPU
counts the master (SMC-40) step motor steps and samples the actual encoder position periodically. If
the distance traveled is less than the specified lag distance, then a stall condition is triggered. The CPU
decrements the stall-retry counter and notifies the SMC-40 of the stall event. One of two operations
are triggered:
1. If the retry count is not zero, a new index is computed from the actual position and target
position. The SME-40 will initiate a new (hopefully shorter) index. If subsequent stall detects
occur, the retries continue until the retry counter reaches zero. The position maintenance mode is
then started.
2. Hunt (position maintenance) is used when the encoder position wanders outside of the specified
deadband (encoder count) distance. The encoder CPU generates step and direction signals to force
the position to be equal the target position. The “hunt” speed is specified with the “v” (lower case
V) command. The step-rate is without ramp and is RPM compensated for the specified microstep
resolution.
If the hunt mode is triggered because of an early stall exhaust, the step distance can be large. If the
motor motion is obstructed, stepping attempt will be continuous, until an abort is executed. Whenever
the position drifts outside the deadband, repositioning to the target position will be exact (as opposed
to just within the deadband).
16
7/11/2008
SMC-40
PERIPHERAL DEVICES
SME-40 Pin Description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Signal
D0
Xstep
C-D
Reset
GND
bu_bat
Xdir
Step
SDA
SCL
RD
WR
D7
D6
VCC
D5
D4
D3
D2
D1
Description
Position data 0
Step feedback/error status to SMC-40
Data control
Pull-up to 5 volts
Power ground
Used when implementing battery backup
Direction feedback error status to SMC-40
Motor step pulse input (SMC-40 output) –used for stall detection
Bi-directional I2C bus
Bi-directional I2C bus
Read counter pulse
Write counter pulse
Position data 7
Position data 6
+5 volt power input
Position data 5
Position data 4
Position data 3
Position data 2
Position data 1
Note:
1. Absolute maximum voltage +5.5 volts on any input.
2. All external inputs must be isolated with appropriate buffer circuitry, using LM339 comparators
is recommended.
17
RS232 - TXD
RS232 - RXD
RS-232
RXD-
RXD+
TXD-
TXD+
RS-422
GND
+5V
11
12
10
9
3
+5V
Vin
2
3
RXD
TXD
PTYi/o
Mvg
Dir
Step
3.3V
1
19
2
18
8
9
10
11
12
13
14
15
Jumper
3.3k
SCL
SDA
Xdir
Xstep
WR
RD
CS
C/D
D0
D1
D2
D3
D4
D5
D6
D7
Port 1
Port 2
Port 3
Port 4
SMC-40
Port 5
Port 6
Led 1
plcc28
Led 2
LimA
LimB
GO
SS
Home
Expansion to
more SMC-40's
Party Line
4
1
2
13
14
23
24
15
16
19
25
3
26
5
24 bit encoder counter
LOAD
GATE/RS
17
18
3
4
2
+5V
PHASE A
PHASE B
4
5
75ALS180
Out
Encoder B
6
7
5
VCC
GND
20
Encoder A
VCC
14
GND
1
GD
GND
6
7
3.3V
21
GND
7
rst
6
3.3k (2)
+5V
+5V
ENABLE
DIR
STEP
Step IN
BU_BAT
D0
D1
D2
D3
D4
D5
D6
D7
WR
RD
C/D
15
Vcc
SCL
SDA
XDIR
XSTEP
SM0-40 Analog Processor option
+5V
12
11
28
10
27
22
20
8
6
1
20
19
18
17
16
14
13
12
11
3
GND
5
10
9
13
2
rst
4
+5V
SCL
SDA
XDIR
XSTEP
+5V
SME-40
10
9
7
2
+5V
step/A in
DIR/B in
DACout
JOY in
+5V
18
19
3
14
SCL
SDA
SMO-40
6
5
NV2048
+5V
SME-40 Encoder Processor option
15
Vcc
+5V
Gnd
5
rst
8
VCC
GND
7/11/2008
10K
4
18
4
7
A0
A1
A2
TST
1
2
3
7
100K
5
6
2K EEmemory Option
100K
0-5V in
ADVANCED MICRO SYSTEMS, INC.
PERIPHERAL DEVICES
Peripheral Device Interconnect Diagram
Please refer to the IBC-400 product manual for complete schematics- with buffering.
Note: Not shown here is the SIN-11 serial interface adapter, which is highly recommended to
simplify serial software.
SMC-40
PERIPHERAL DEVICES
SMO-40, SME-40 Specifications
Vdd= 4 to 6Vdc, Ta= –85 to +85 degree C
Sym Parameter
Test conditions
Icc
Power supply current Vdd=5 volts
Ain
Analog inputs
Vdd=5 volts
Vinl Logic inputs
4.0V<Vdd<6.0 volts
Vin
Logic inputs
4.0V<Vdd<6.0 volts
h
Iinl
Input low current
Vin=0.4 volts
Ilh
Input leakage
Vin=Vil or Vih
Vol
Output low
Iol=3.2mA
Iol
Output sink current
Absolute maximum
Voh Output high
Ioh=-30uA,Vdd=4.5
volts
Min
-0.5
-0.5
Typ
15
Max
25
5.5
Vdd+0.
5
-50
+2
0.4
20
Unit
mA
V
V
V
uA
uA
V
mA
Vdd-0.7
SO20 Package Specifications
19
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising