Running direction control

The running direction of the stepper motor is determined by the energizing sequence and energizing method of its internal windings. Because the two-phase double four-beat stepper motor is not easy to lose step, and the control accuracy is relatively high, this article uses two-phase double four-beat working mode to control the stepper motor.

Running speed control

Controlling the running speed of a stepper motor actually controls the frequency or phase commutation period of the drive pulse. That is, in the process of acceleration, the frequency of driving pulses is increased; in the process of deceleration, the frequency of driving pulses is reduced. The control of the driving pulse frequency can be realized by means of software delay and hardware interrupt.

Software delay refers to writing a delay subprogram according to the required delay time constant. When the CpU executes the delay subprogram, the system achieves the purpose of delay. With the software delay method, the CpU is always occupied, which reduces the CpU utilization.

The programmable hardware timer can count the system clock pulse, and the count value can be set by programming. When counting to a predetermined number of pulses, the timer generates an interrupt signal and the system gets the required delay time. Timer delay can improve CpU utilization.

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