In this project, I developed a system to control a stepper motor's angle and direction using the Arduino Uno and DRV8825 driver. The goal was to create an intuitive user interface using Python's Tkinter library, enabling users to adjust the stepper motor's position and direction with ease.
The project involved wiring the Arduino Uno and DRV8825 driver, establishing the necessary connections with the stepper motor, and implementing the control logic. The Python-based GUI developed with Tkinter allowed users to interact with the system, specifying the desired angle and direction for the stepper motor.
Before you start creating or even thinking about your circuits, you first need to understand what kind of stepper motor you have and what that means for your circuit. The most common stepper motors are usually either 4-wired, 6-wired, or 8-wired.
Stepper motors can also be either Unipolar or Bipolar. Bipolar motors generally have more torque and are more efficient than unipolar motors. In contrast, unipolar motors use only half of each winding coil at a given time, resulting in lower torque and efficiency.
The DRV8825 is intended for 4-wire bipolar stepper motors. So what do you do if you have a stepper motor with more wires? Well, in a 4-wire motor, one coil is connected via a positive and negative side. The easiest way to think about it is that this coil is represented by a pair of pins on your stepper motor. 6 and 8 wire motors have what are called center taps in between these pairs. These center taps are intended for high-torque purposes and we do not need them. So you simply connect your 6 or 8-wire stepper motor as if it were a 4-wire Bipolar motor. To do this you skip the center taps as such…
(A+ goes with A- | B+ goes with B-) We skip ACT and BCT (A Center Tap, B Center Tap).
Make sure to adjust the current limiter appropriately to your stepper motor so as to not burn it out. To do this, adjust the potentiometer (the screw beside the ENABLE and M0 pinouts) clockwise to lower and counter-clockwise to higher. To check the current limit, take a potentiometer and check the reference voltage (Vref) by resting your red on the potentiometer and your black on the GND LOGIC pin. The current limit is found by the following formula…
I found that having the current limit set at 1A worked just fine to move the motor, so adjust the current limiter until your reference voltage reads close to 0.5V. * Apologies for the crowded circuits and poor visibility but this is what my circuit looked like in the end.
