Moving to NEMA motors

Hello,
Using the Arduino UNO, 28byj-48 motor with the ULN2003 driver board, the Arduino listens for a digital pulse from the camera controller and commands the stepper to move. The setup works well but I would like to perhaps move to a system that provides more accuracy and better repeatability. Adding a SKU: POLOLU-1207 and the SKU: ADA1438 to the Arduino, can the code i have written be used again? It is really simple with basically the Stepper.h library and a single digitalRead. What other components are required to complete a NEMA motor setup?

Thank you,
Stuart

2 Likes

The bigger motor will require an external power supply - it will not run from the Arduino 5v supply. This external supply could be the 9-12v supply you are using for the Arduino or, if you are powering the Arduino from a 5v supply such as the USB, a separate 12v (or higher) supply.

The existing code will not work with that shield as it uses I2C, however the libraries will provide plenty of examples to enable you to rewrite the code. Rather than using a shield, which may have features you don’t need for this application, you could use a separate driver module. There are many available, ranging from simple replacements for the ULN2003 you are already using (which wil require no changes to your code) to controllers with adjustable current limiting and microstepping control. If a dedicated controller requires changes to your code it will be a simplification compared to what you are now using (step/direction rather than h-bridge).

2 Likes

Thanks Jeff105671, you have given me some information i have never had and pointed me in a new direction. Looking through the excellent Pololu website i have more information about the driver modules and thankfully they are available here in Core. The A4988 for example can provide the micro steps i am looking for. The code writing wasn’t too bad but i’m struggling with putting the available hardware together and the more i look the more i find. And h-bridge is a new phrase for me this morning!

2 Likes

H-bridge refers to the arrangement of the driver transistors. Roughly speaking, you can drive a stepper 3 ways - simple transistor switches such as ULN2003 for unipolar motors, where you use the Arduino GPIO pins to create individual stepping pulses, a simple H-bridge which still requires separate pulses to be generated in the Arduino, but where circuitry reverses the current direction in the coils so they can be used with bipolar motors, or a controller that requires only a direction and step signal, and calculates the required pulses for you. Full function controllers such as A4988 are now available at prices that make the other options pretty much redundant.

2 Likes