How to use current feedback in Jrk 21v3?


Looking for a current PID controller for a DC brush motor, I found the likely answer: the JRK 21V3. However, after reading the controller pdf I didn’t find the way to feedback the motor current in the Jrk FB (feedback) pin. Does anyone know how to do that ?, Is that possible ?.



Unfortunately, the jrk was not designed to be a PID current controller.

If you want, I could tell you how you could attempt to modify it to be one, but it would require soldering a wire to one of the SMD components on the board and you would only be able to drive the motor in one direction. But since I’ve never done this before, I’m not sure it would work.



That is what I need, to know where to connect a wire and get current feedback. However, why is only possible to move the motor in one direction ?. I think if the controller knows the motor direction it can change the pwm sent to the H bridge, but I guess this will require a change in the Jrk firmware.

Thanks again,


The current sensing circuit on the jrk outputs a voltage which is proportional to the current flowing through the motor, but the output contains no information which the direction the current is flowing. If you connect this output to your FB pin, then a value of 0 for the jrk’s Feedback variable would corresponds to no current. A value of 500 would correspond to some amount of current, either in the forward direction in the reverse direction. If you set the jrk’s target to 500, then there is no way for the jrk to know if you want to drive the motor forward or backwards. You would want to configure the jrk so it only drives the motor in one direction, using the Max Duty Cycle setting.

Is this acceptable for your application or do you need to drive in both directions?