Jrk 21v3 Deceleration Control

I am using the Jrk 21v3 for single direction motor speed control with a pot connected to the analog input and no feedback. I can set the max acceleration under the Motor menu, but would also like to control the deceleration. Is there a way to do this without controlled ramping of the analog input voltage?

Thank you for your time.


The standard jrk firmware has no limit on how fast the motor can decelerate. Unfortunately, there is not enough room left on the jrk to include this feature without losing others. If this feature is important to your application, you can find custom versions of the firmware with deceleration support in this forum thread. There are two files in that thread; please take note of whether you have a jrk 21v3 or jrk 12v12, and download the correct firmware for that version. Additionally, please note that the max duty cycle limit and current limit features were removed from this version of the firmware to make room for the deceleration support.

As noted in that thread, after loading the correct settings file onto your jrk using the Jrk Configuration Utility, you can set deceleration limits in the Motor tab using the boxes labeled “Max. duty cycle”.


Thank you Brandon! The custom firmware added the deceleration feature nicely.

What this leads me to is the second challenge of stopping the motor with an external trigger using the deceleration setting. Pulling the Analog input low is difficult to balance with the speed range needed for direct control via a pot. The Reset input stops the motor abruptly.

Is there an option I’m missing to externally inhibit the motor in a way that it stops and starts using the acceleration and deceleration settings?

The jrk does not have a separate option for some kind of second input to stop the motor like that. I am not sure what you mean when you say that it would be “difficult to balance with the speed ranged needed”, but the functionality you are describing should be possible by using an external switch to connect the analog input low when toggled with the jrk configured appropriately.