How To Use Pwm To Control Gear Motors; En/A/B Three Wire Driver; A/B Two Wire Interface - Raspberry Pi RoboPi User Manual

RoboPi v1.00

How to use PWM to control Gear Motors

Standard motor drivers normally are controlled by two or three digital signals per motor.

EN/A/B Three Wire Driver

The popular L293D and L298 motor drivers are often configured for EN/A/B three wire control.
Some driver boards permanently tie EN high in order to use only two pins, however I do not
recommend this practice as it is harder on both the motors and batteries (more later).
EN Function
0 Disable the motor driver, motor coasts
1 Enable the motor, motor turns in direction specified by A or B
Note:
Some motors have an active low input, in which case 0 enables the motor, and 1 coasts.
Check the data sheet for your motor controller (or motor controller chip) for details.
A B Function
0 0 Break
0 1 Rotate in one direction
1 0 Rotate in opposite direction
1 1 Break

A/B Two Wire interface

The inexpensive low current L9110S h-bridge is one example of a two wire A/B interface, however
many L293D and L298 boards tie EN high to effectively become two pin drivers.
A B Function
0 0 Break
0 1 Rotate in one direction
1 0 Rotate in opposite direction
1 1 Break
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User Manual v0.60
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Copyright 2014 William Henning
2014-01-27