Pololu TReX Dual Motor Controller Troubleshooting

Hi everyone, I’ve got a Pololu TReX Dual Motor Controller that’s powered by a 12v battery supply. It’s connected to an Arduino Uno (powered separately) on the TTL inputs. I can see that there is 5v going across both the SO and SI points. I can see from my Arduino serial output that it is sending the correct commands (0xC2) but there is 0V on both M1 and M2 outputs used to drive my motors. Does anybody have any troubleshooting advice?

Hey Chris,

I’m having a look at the spec sheet for the TReX right now and it looks like there are quite a few status LEDs that could help us identify any issues. Would you be able to have a look at these and tell me what you see?

These ones interest me:

  • When the TReX starts, the 2 status LEDs should flash rapidly 5 times. What colours are these?
  • When a signal is being sent to your motor, there should be green LED lights showing the intensity and direction of the motor signal. Does this look like it’s matching up?

For reference I’m using this document: https://www.pololu.com/docs/pdf/0J1/TReX.pdf specifically section 3.d. There might be some other indicators that could be of use.
Let me know how you go! :slight_smile:

Hey Ben, thanks for the response. I had taken a look at that document. My status LED’s flash red five times, the power LED is a strong blue (not dimly lit) but I’ve never seen any of the motor indicator LED’s light up. I’m not using any of the jumpers which I believe is the correct thing to do when using the TTL pins also

Yep, I think you have the jumpers right.
While it is running, is the red status LED on, and the green LED flickering when you send a command?