2031 LP CIRCUIT THEORY

Stepper Motor Control Circuits

The stepper motor is controlled by two outputs on port B of UCD4, the 6522 VIA, STEP0 and STP1. These two lines are converted by UE2 to a binary four count to drive the four phases of the stepper motor. Outputs Y0, Y1, Y2, and Y3 from UE2 are inverted by UF2. The outputs of the inverters drive Q4-Q7. The current output from these transistors drives the individual phase coils in the stepper motor and returns, to the 12VDC supply. CR1 3-CR1 6 suppress the CEMF developed by the motor coils.