Pololu trex jr dual motor controller dmc02

I am working on a skid steer rover for indoor use with wheel encoders and a pixracer for a flight controller, running ardurover dev 4.0.1. I am uisng outputs 1 and 2 for throttle left and right. Output 3,4 are wheel encoder right and outputs 5,6 are wheel encoder left. I have read through the manual for the motor controller here I have removed the channel mix jumper so motor 1 and motor 2 can be controlled by the controller separately I have attached the 1,2 outputs from pixracer to channel 1,2 on the motor driver and left the RC/analog jumper left to RC on the trex. I cannot for the life of me figure out how to get anything to work when connected to the pixracer. I have plugged in motor 1,2 from trex jr to a servo tester and can get the wheels to spin then but not when connected to the pixracer. I have made sure and set thr brd_count to 2 to allow two PWM outputs on pin 1 and 2.

Does anyone have knowledge of setting up a pololu trex jr motor controller?

I have read through these posts here, here, and here but have not figured it out quite yet.

I think the most likely cause is a conflict between the wheel encoder input (on channels 3,4,5,6) and the servo/motor output (on channels 1,2). Could you try disabling the wheel encoders (WENC_TYPE = 0, WENC2_TYPE = 0) and put BRD_PWM_COUNT = 6 and check if the wheels moves?

If you’ve got a dataflash log that might help too in case it’s something completely different (like the vehicle isn’t armed or the SERVO1/2_FUNCTION parameters haven’t been set correctly.


Great news. Re the RPM message not working, I think this is a change in Rover-4.0, there is a wheel-encoder message but perhaps that’s not showing up in MP (unless the Ctrl-F Mavlink Inspector is used). We also need to update the wiki it seems to make this clear.

Sounds like progress. Having to set the mid point to 1750 is a bit unusual. It should be 1500 normally.

I see above there’s a link to some logs, are those still valid or have things changed much since these logs were produced?