Search

Motorola is introducing an integrated circuit for driving a two-phase stepper-positioning motor with the ability to provide up to 350 mA to each of a two-phase motor's two coils. The MC3479P chip consists of four input sections, two drive stages, and an output to indicate the phase-A drive state. The integrated circuit features selectable clockwise or counter-clockwise motor operation and the ability to rotate either one full step or one half step.

A circuit using an MC6809 microprocessor and MC640 programmable timer controls up to three stepping motors simultaneously. The motors' speed and number of revolutions can be controlled separately using the timers as square-ware generators and single-shots. The circuit is illustrated and an assembly language program for simultaneous control of two motors is given.