A simple and versatile stepper motor driver and controller

For mechanical applications requiring precise control, stepper motors offer many advantages over simple d.c. types. They can start and stop virtually instantly and move in tiny, precise increments. Forward and reverse operation is simple. Accurate speed control is easy to achieve through step rate, and shaft position may be tracked simply by counting the steps.

There is a downside though, since electronic circuitry is required to generate the coil drive sequence needed for operating these motors. Special stepper driving ICs are available but these usually offer only one out of several possible drive methods, and they often draw too much supply current for battery applications.

Additional circuitry is usually required to generate step and direction inputs so it is often a better idea to use a custom programmed PIC microcontroller for complete step sequence control, and perhaps also the controlling system.

For the experimenter who has acquired a stepper motor, the priorities will usually be to check out its speed, torque and the effects of different types of drive sequence. It might also be desired to bolt it into a prototype design and rotate it back and forth in a controlled manner to check whether the project is likely to work.

This PIC Quickstep project allows rapid testing of this kind with many options that can be tried out to see their effects.