Problem with controlling 24v23 simple controllers

Hey all,

My name is Jorn and I am a student at Fontys in Eindhoven, Netherlands. Please excuse my English.

For a project on school we are using 4 Pololu 24v23 simple motor controllers that are being controlled by a Parallax proto board.
We use a 24v/8.2A power supply for testing two 24v23 attached to two DC motors with encoder. The wheels are floating in mid air.
We can drive the wheels in all direction and is working, but one of the two is getting a unusual amount of errors. The other one is getting almost 0 errors.
But when we disconnect the “0-error” 24v23 controller, the other one is getting less errors then before. But still a lot.

At the moment we are clueless of why this is happening.
I hope this can be solved easily.

Best regards,


Hello, Jorn.

I am sorry you are having problems with your Simple Motor Controllers. It sounds like you might have connection issues. Could you post photos of your setup and close-ups of the problematic board? Could you also tell me what errors are occurring (you can get information about the errors by checking the “Errors” box under the “Status” tab of the Simple Motor Control Center)?

- Jeremy

Thank you for your fast response.
Also Wednesday is our project day, the only day in the week we work on this project.

The errors are serial errors. Most of them are noise, some are format errors.

We will test the system with a battery today, it may be caused by the power supply.

Which unit produces the errors? If it is the one closer to the power supply, your theory that the power supply is the cause of the faults seem reasonable and changing the power supply to a battery might help. By the way, from your photos, it is hard to tell if the through-hole capacitors are soldered in. If they are not, you should definitely solder them on.

- Jeremy

The capacitors are soldered in.
The one that produces the errors is the one closer to the power supply.
We have not tested with a battery yet.

From the photograph, it appears that you are attempting to use serial communications in parallel.

That should work for one TX pin on one device communicating to two RX pins on two other devices, but probably will not work for two TX pins in parallel, attempting to communicate with one RX pin. If the two TX pins don’t function with identical timing, they will conflict and that would lead to communication errors.

Nice catch Jim! Jorn, if you want to communicate with both SMCs, you might consider using the TXIN pin to daisy chain the two controllers. You can read more about this in the “Daisy Chaining” section of the Simple Motor Controller user’s guide.

- Jeremy