Can I use an SKR Pro with external drivers

  • I'm thinking about replacing my current CNC controller board (wincnc) with a BTT Skr Pro running RRF. The CNC has high-voltage external stepper drivers that I want to retain.


    1. Does the SKR Pro support external stepper drivers (i.e. step/dir pin output) ?
    2. Does RRF support this kind of usage?
    3. Is there a better board I should look into. I'm using a Duet3 in my 3d printer and love it but it doesn't support external steppers.


  • @markz I use an SKR Pro with external drivers on my CNC machine.
    So the answers are

    1. Yes. I made my own little adapter boards to break out the pins but you can also buy these
    2. Yes. you just need to set the appropriate timings
    3. Duet 2 supports external drivers using an external breakout board or you can get a duet 3 with a 1XD board to connect an external driver, although one would be required per driver

  • @jay_s_uk Thanks for the great answer. I didn't realize the breakout board for the duet2 was such a good fit also (albeit noticeably more money). My CNC hasn't got much on it at all (other than 5 motors and a relay) so I don't need much hardware I/O.

    How do you like the SKR Pro with RRF? I'm not excited about what seems to be a pretty serious port of RRF to the STM processor. I would like to test RRF (cheaply) since it's a major change to my CNC but not if I spend piles of time building software and testing.

  • @markz I find it works pretty well.
    I have 5 motors, control of the VFD spindle, a paneldue and 2 probes. I also use the wifi version rather than the SBC version.
    It all works particularly well.
    The STM port works just as well as the duet 2/3 and probably sits somewhere between the duet 2 and duet 3 in terms of capability.
    I wouldn't have any issue with recommending it for another CNC user.

  • @jay_s_uk Thank you very much for the reply.

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