Access register via UART

I would like to write into the feedback and max duty cycle register via the UART interface.
Does someone know to do that?

Thanks to help me


Hello, C.Duvoisin.

Are you asking about the one of the jrk motor controllers with feedback? Unfortunately, there are no serial commands for doing that. All the serial commands are documented in the jrk user’s guide.

If you tell me what problem you are trying to solve, I might be able to recommend a different way of doing it.


Hello, DavidEGrayson.

Yes, I have the Pololu jrk21v3.

I would like to do a carthesian system.

For doing this, I control 2 motor controllers by the UART interface and use two potentiometer as feedback.
I use the controller in position mode and I would like send it a position and a speed via the UART interface.
After, I would like edit the scaling value (Minimum and Maximum) by the motor position when he hit two ending switches.

Is this things possible?

Thanks for your help


It is possible to set up a jrk with a potentiometer for feedback and then send positions to it via its UART interface. The serial command you would use is called “Set Target” and it is documented in the jrk user’s guide.

Unfortunately, you can not send speeds to the jrk via the UART (or any other interface) when you are doing position control. Instead, what you can do is send constant stream of Set Target commands that slowly change from the current position to the desired position. The rate of change of the target will determine the speed of movement.

Also, you can not change the jrk’s input or feedback scaling values over the UART. Instead, you could manually change them using the Jrk Configuration Utility or you could scale the target values on your microcontroller before sending them to the jrk.