Attached are the Altium Designer project files for a stepper motor driver circuit. The circuit uses a LM317 voltage regulator and an A3967 micro-stepping motor driver. The motor can be controlled using a microcontroller wit two digital outputs. Connect ne output to STEP and one output to DIR. Bringing “STEP” from low to high commands one rotational step of the motor. Changing the logic level of DIR changes the direction of rotation of the motor.
The A3967 chip can be used to control any bipolar stepper motor. The circuit also uses a trimmer potentiometer to adjust the current to the stepper motor. The current ranges from 150 to 750 mA per phase. The required input voltage to the regulator is between 8 to 30 VDC.
The PCB design is that of a 2 layer board using ground and power planes through the polygon pour function in Altium. Open “MotorStepper.PrjPcb” to get started.