Complete Stepper Motor Control with the SAA1027 (MEC164E)

This shield circuit is adapted from my book Robotics, Mechatronics and Artificial Intelligence (sold out) published in the United States. It can be used as a shield for stepper motors in mechatronics or robotics projects or as a building block for more simple projects.

The SAA1027 IC is designed to include all the functions needed to control a stepper motor with currents up to 350 mA. The SDA1027 is manufactured by Signets, and the basic application is shown by Figure 1.



Figure 1    Stepper motor control using the SAA1027.
Figure 1 Stepper motor control using the SAA1027.



The bias resistor must be 470 Ω × 1/2 W if the stepper motor needs less than 250 mA current. If the current is in the range between 200 and 350 mA per phase, this resistor value will be reduced to 150 Ω × 1 W.

This block has three inputs:

1. The pulses that move the motor are applied to the trigger input.

2. To the direction input, we apply the logic level determines whether the stepper motor runs forward or backward.

3. The set input, when connected to ground, continuously supplies power to two of the windings, braking the motor.