MTS2916A DUAL FULL-BRIDGE
STEPPER MOTOR DRIVER
EVALUATION BOARD USER’S GUIDE
Chapter 2. Installation and Operation
2.1
INTRODUCTION
The MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board demonstrates the capabilities of the MTS2916A to control both windings of a bipolar stepper motor.
The board also demonstrates the capabilities of the MTS62C19A, which has the same functionality, but different pin assignments. A PIC16F883 is utilized for motor control processing.
This evaluation board incorporates features through the implementation of push-button switches and a variable speed input potentiometer to exercise a stepper motor in
Full-Step, Half-Step, Modified Half-Step and Microstepping modes. LEDs indicate a binary representation of which mode has been selected. The evaluation board and the stepper motor can be powered from a single power input J1 (7 V
DC
to 12 V
DC
) with jumper JP2 installed. For higher motor voltages, make sure JP2 is not installed, and connect V
LOAD
at J4. Numerous test points have been designed into the board to allow easy access.
2.2
POWER CONNECTIONS
The MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board uses a combination of terminal blocks, test clips and one DC power jack for power connections.
Connections are as follows: a) Motor Output Connections:
- J2-1(A3), J2-2(A1), J2-3(B1), J2-4(B3), J2-5(TP21)
- TP11(A1), TP12(A3), TP13(B1), TP14(B3) b) V
LOAD
(Motor Supply Power):
- J4-1(PGND), J4-2(V
LOAD
)
- TP20(PGND), TP18(V
LOAD
)
WARNING
Do not connect more than 16V to these motor supply connections while Jumper JP2 is installed.
c) V
LOGIC
:
- J1-1(VLOGIC), J1-2(AGND)
- TP2(VLOGIC), TP5(AGND)
2012-2013 Microchip Technology Inc.
DS50002058B-page 11
MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board User’s Guide
FIGURE 2-1: Power Connection Diagram.
2.3
FEATURES
The MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board has the following features:
• Push Button mode, Run, Hold and Direction control
• Potentiometer variable speed adjustment
• LED mode indication
• Maximum winding current with the combination of R s
, V
I0/I1 logic inputs
REF
and conditioning of
• PICkit
™
Programming connector (J5) to implement user-created code
DS50002058B-page 12
2012-2013 Microchip Technology Inc.
Installation and Operation
2.4
GETTING STARTED
The MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board is fully assembled and tested driving a dual coil bipolar stepper motor.
2.4.1
Powering the MTS2916A Dual Full-Bridge Stepper Motor Driver
Evaluation Board
Follow these steps to power-up the board:
1.
With the supply turned OFF, connect the power to the logic portion of the evaluation board at J1 with the specified voltage (7 V DC to 12 V DC ). The logic portion of the evaluation board will typically draw less than 50 mA.
2.
If the user’s stepper motor requires a voltage that is compatible with the logic supply voltage and the user’s source can handle driving the stepper motor windings, install JP2. DO NOT connect power at J4. If powering up the stepper from an additional supply, DO NOT install JP2 and connect the stepper motor supply to J4. J1 power will still be required for the logic supply.
3.
Connect the bipolar stepper windings to J2 per the schematic diagram.
4.
Turn ON the power supplies. Power sequencing is not required due to the undervoltage lockout circuitry.
5.
Toggle the Mode switch to cycle through the five modes, as indicated by the binary LED count.
6.
Press the Run switch once to tell the PIC16F883 to send drive information to the
MTS2916A with minimal (1V) V
REF
. Subsequent Run presses increase V
REF approximately 1V up to 5V maximum. This increases the current regulation
by threshold.
7.
The Hold switch tells the PIC16F883 to command the MTS2916A to hold the motor position.
8.
The Direction switch tells the PIC16F883 to command the MTS2916A to change the direction of the motor.
9.
The Speed Adjust Potentiometer (R4) varies an analog voltage that is read by the PIC16F883 Analog-to-Digital Converter, and varies the speed accordingly.
Logic inputs I0 and I1 control load current levels are shown in Table 2-1 :
TABLE 2-1:
I0
0
1
0
1
CURRENT LEVEL CONTROL
I1 Comparator Trip Voltage
1
1
0
0
V
TRIP
= 1/10 x V
REF
V
TRIP
= 1/15 x V
REF
V
TRIP
= 1/30 x V
REF x
Output Current
I
MAX
= V
REF
/10 x R
S
2/3 x I
MAX
= V
REF
/15 x R
S
1/3 x I
MAX
= V
REF
/30 x R
S
0 (no current)
2012-2013 Microchip Technology Inc.
DS50002058B-page 13
MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board User’s Guide
2.5
KEY COMPONENTS
Some of the key components on the evaluation board may need to be adjusted, depending on the characteristics of the utilized motor. The fixed Off Time (t
OFF
) is set by the combination of R t
and C t and is determined by the expression: t
OFF
= 1.1 x R t x C t
.
The evaluation board is designed with t
OFF
= 24.2 µs.
The amount of time it takes for the winding current to reach the regulation point is determined by multiple factors, such as motor voltage, inductance, resistance and the set point threshold.
The set point threshold is determined by the states of I0/I1, V
REF
and the sense resistance value. For details on set point thresholds and component values, see the
MTS2916A Data Sheet (DS22259).
Explaining the effects of the motor characteristics is beyond the scope of this user’s guide; however, the t
OFF
time of 24.2 µs was chosen to cover most motor applications while trying to maintain a switching frequency above the 20 kHz audible range.
There is a single pole filter in the sense feedback used to set a break frequency of approximately 80 kHz. Depending on the application, this break frequency may need to be adjusted. This may be apparent when designing to regulate at low currents.
2.6
MODES
The following plots were taken from a single winding of a bipolar stepper motor.
TABLE 2-2: MODE 1 VALUES
Full Step
CH1: Phase 1
CH2: I01
CH3: I11
CH4: Coil Current
V
REF
= 1.94V
Speed = 0.43V
V
LOAD
= 24V
DS50002058B-page 14
FIGURE 2-2: Mode 1 Plot.
2012-2013 Microchip Technology Inc.
Installation and Operation
TABLE 2-3: MODE 2 VALUES
Half Step
CH1: Phase 1
CH2: I01
CH3: I11
CH4: Coil Current
V
REF
= 3.87V
Speed = 0.43V
V
LOAD
= 24V
FIGURE 2-3: Mode 2 Plot.
TABLE 2-4: MODE 3 VALUES
Modified Half Step
CH1: Phase 1
CH2: I01
CH3: I11
CH4: Coil Current
V
REF
= 3.87V
Speed = 0.43V
V
LOAD
= 24V
2012-2013 Microchip Technology Inc.
DS50002058B-page 15
MTS2916A Dual Full-Bridge Stepper Motor Driver Evaluation Board User’s Guide
FIGURE 2-4: Mode 3 Plot.
TABLE 2-5: MODE 4 VALUES
Micro Step
CH1: Phase 1
CH2: I01
CH3: I11
CH4: Coil Current
V
REF
= 3.87V
Speed = 0.43V
V
LOAD
= 24V
DS50002058B-page 16
FIGURE 2-5: Mode 4 Plot.
2012-2013 Microchip Technology Inc.
