Development of a Stepper Motor Speed and Direction Control System Based on an 8085 Microprocessor Training Kit

Stepper motors convert digital pulses into precise angular steps and are used in printers, positioning tables and small machines. This paper presents a stepper motor speed and direction control system based on an 8085 microprocessor training kit. The processor generates the excitation sequence through a parallel port and a driver circuit, speed is set by the delay between steps, and direction by reversing the sequence. The relation between delay and speed and the limit of reliable stepping are evaluated by simulation. In simulation the five speed settings gave step intervals of 1.63-16.0 ms (19-184 rpm), and the motor followed the commands without losing steps down to an interval of 1.5 ms (667 steps/s).