Using Stepper Motors as RC Position Servos or Continuous Rotation Servos

I recently 3D printed a bracket to attach the antenna boom from my GSE to a NEMA 42 stepper motor. That is 5kg worth of motor in the vice! The antenna boom was clamped to the mount and dropped onto the 3/4" (keyed!) motor shaft. Drive was accomplished with a 24v PSU (15A max) and a TIC 36v4 drive board. This was controlled through a RC tranmitter and receiver. So this will be the azimuth drive for the Automatic Antenna Tracker. Works well I think.

Next up will be to add the altitude drive on top of this motor, using a similar stepper motor approach, to give me a full altazimuth mount. I will also take advantage of the homing features of the driver PCB for both axes.

Those TIC 36v4 drivers are amazing. They allow you to use a stepper motor in either rate or position modes with all sorts of control inputs (i2c, USB, step/direction, serial, RC PWM, analog voltage. It can also support a quadrature encoder and homing if needed.

More info here:

Pololu have other versions of the stepper drivers that have less power and functionality. You need to figure out what one is suitable for your application. Being able to set either rate or position functionality it can be used for both ardupilot AAT and u360gts AAT. Being able to make a stepper function like a RC servo or continuous rotation servo is really useful.

Share and Enjoy :slightly_smiling_face:


I am building an AAT driven by a stepping motor. The pitch uses closed-loop drive.