When we’re not using a stepper motor to ensure precise positioning of a robot element, it can be used as a traction motor, in place of the standard modified servos presented elsewhere. Under these conditions, there’s no longer any need to ‘count the steps’ the motor has to make, as all we want is to make it rotate continuously in one direction or the other.

Several solutions are open to us for driving the motor, a number of which are presented in this issue: using a specialized stepper motor driver IC, using one or more suitably-programmed microcontroller parallel ports, or building a driver based around conventional logic ICs.