24v23 High powered controller overheating via usb only


I am having some issues with my controller. I had it running over usb to my computer and the software/hardware was working fine.

I have a 9V input connected to Vin/Gnd, a 12V DC motor connected to outA/outB.

While still connected via usb (to check if it was working & for errors), I then tried to send data over rs232 with the rx/ground pins connected and suddenly the device started overheating extremely quickly.

Now the device does not activate with just 9V input (no green/orange light). Upon connecting the usb, the green light comes on (on the device), the computer gets a ‘overpowered hub’ message from the usb, and the device immediately starts overheating.

Did i send a bad message accidentally? And can this problem be rectified?



I’m sorry to hear you are having trouble with your Simple Motor Controller. The SMCs work with logic level (TTL) serial, not RS-232. From the user’s guide:

It sounds like the RS-232 voltages, which can be significantly outside the 0 - 5V range the RX pin can tolerate, have damaged the board’s microcontroller and created a short between power and ground, in which case the only way to fix it would be to replace the microcontroller. If you would like for us to take a look at it and see if it can be repaired, please contact us directly at support at pololu dot com with your order information and we can give you an RMA number.

- Ben

That is rather disappointing, especially as my current location does not allow for quick access to more pololu controllers.

Thanks for your help.