JRK12V12 and max current limit

Hello polulu team,

i want to use the jrk12v12 controller for control force simulation in a flightsim.
The controler offers the max current limit, so iguess it should be possible to use this controler for force controling, but only if i can change the max current value on the fly via serial oder USB-virtual-interface!

The current control force changes permantly in a plane, so i need to change the max current in the controler as well.

I looked into the user guide, but i did’nt found anything about this.

Any change to control the current (force) of the JRK12V12 in any way and not only with the config tool??



Hello, Thomas.

Unfortunately, there is no good way to change the current limit of the jrk on the fly. You might be able to set up something using one of our current sensors, connecting the output of the current sensor to the FB pin of the jrk, but I have not tried this and I do not know what problems you are likely to encounter.


Hi Dvis,

first of all thanks for the quick answer:-)

I watched you current sensors and understand the way they work.

But i wonder how could it control the current? The sensor meassures the current and distribute a dc voltage which respects to meassured current.

To connect this to the FB is the same as a pot who is not linked to the motor but connected to FB.

The motor will turn as long as the pot reaches the existing target.

The more delta between target and FB input the faster turns the motor.

Its maybe possible that the current increases in this case, but the motor must not turn to provide more force. Rather it should hold its position, but with variable force.

Lets say the motor is on the target position with 2 amperes limit. If i try to move the motor by hand there is a resistance, but with a break trough i can turn it nevertheless. When i now increase the current limit in the config tool to i.e. 7 amperes, i need much more power to turn the motor. But the motor will not turn before i override the holdingforce and than it will only turn back to the target position.

This is what i need…

Is there only “no good way,” or really "no way to change the limit via serial?

Is there another motorcontroler who i capable to take external current control inputs??

Kind Regards and sorry for my english


If you are comfortable with programming in C#, you could download the Pololu USB SDK and familiarize yourself with it. That would allow you to write a program that talks to the jrk’s native USB interface and changes the current limit. Alternatively you can just use the SDK to compile JrkCmd, a command-line utility that is capable of changing all the settings. However, you should be careful because the current limit is stored in EEPROM, which is only rated for 100,000 erase/write cycles.


Hi David,

thats important off course! Since the forcedata changes very very often, the 100.000 limit would be exceeded in some days. To bad.

Another approach. I read on the net, that many torque controller works as follow:

There is a force-sensor (resistor type) mounted on that point where the force applys. This sensor is connected as feedback to the controller like the pot.
Now the force sensor controls the duty cycles of the controller and the torque of the motor.

I must confess, i am not aware of duty cycles and what it means.Does the JRK-feedback input also control the duty cycles or just the speed??

I read that these are two generaly control types on a controller. (Duty cycles/ Speed)



I’m not sure I understand the question. The jrk can be configured in a simple mode where you just tell it the duty cycle to drive the motor at, and it drives the motor with that duty cycle. It can also be configured in more complex modes where you have to connect a feedback sensor of some sort and the jrk automatically varies the duty cycle to try to get the feedback sensor to change to your desired target value. The feedback sensor is typically a potentiometer that measures the position of your system or a tachometer that measures the speed of your system.