Gertboard Motor Controller: L6203

The Gertboard version 1 uses the L6203 DMOS full bridge driver IC for controlling a single motor in forward or reverse directions. The motor driver circuit is a stand-alone circuit with a dedicated fuse F1. If you are building a robot car, you may need to control two motors; therefore, you may need to build two circuits on prototyping board. However, these days you can get a dual DMOS driver PCB for less than a pound on eBay.

Forward / Reverse Control Signals

The control signals fed through MOTA and MOTB determine the rotation of the motor shaft.

MOTA

In order to make a motor shaft rotate in forward and reverse directions the polarity of the power source has to be changed. The DMOS L6203 IC is able to change the polarity using internal power transistors that behave as switches. The diagram above shows four such switches, which are under control by signals from MOTA and MOTB header pins. A signal applied to MOTA, causes two of the switches associated with it to close and provide power to the motor.

MOTB

A signal at MOTB closes an alternate pair of switches thereby changing the polarity to the motor and consequently the direction of rotation.

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