Setting Motor Currents- M906



  • I am tying to learn about setting motor currents, M906. Not sure if this post goes here in FW Installation or Tweaking forum.

    1. If you are using stepstick / stepper drivers with digipots to set Vref, would you use M906 at all ? I used the online configurator and didnt think about it, the M906 is in my config.sys file even though I am using DVR8825's all around, because I choose the wrong board to config with.

    2. If you have a mixed system with digipot boards and a stepper driver boards that are capable to have the current set by firmware, do the values in M906 for digipot drivers matter? Using 0's here does not feel comfortable.

    Example- X & Y have SD6128s, Current Limit is VREF*2, Motors are 2A, current would be 1.0a or 1000ma.

    Z, E0 and E1 are DRV8825's, all at Current Limit is VREF*2, Motors are 1.5A.

    M906 X1000 Y1000 Z0 E0:0 I0

    Thanks in advance

    Dennis



  • @sinned6915 M906 controls the stepper current on the drivers on the Duet and the DueX boards. For the 8825s, it won't set the current.



  • Stephen-

    I am trying to determine if I can MIX digipot drivers and FW current set drivers on the same system. I am working towards 3 independent Z leveling screws.

    Can you have mixed stepper drivers in the system?

    On my stepstick breakout board I will have all DRV8825's for the three Z motors.

    The X, Y, E0 & E1 will be the current setting kind.

    M569 P0 S1 ; Drive 0 goes forwards X
    M569 P1 S1 ; Drive 1 goes forwards Y
    M569 P2 S1 T1.9:1.0:0.65:0.65 ; Drive 2 goes forwards Z1
    M569 P3 S1 ; Drive 3 goes forwards E0
    M569 P4 S1 ; Drive 4 goes forwards E1
    M569 P5 S1 T1.9:1.0:0.65:0.65 ; Drive 5 goes forwards Z2
    M569 P6 S1 T1.9:1.0:0.65:0.65 ; Drive 6 goes forwards Z3

    M584 X0 Y1 Z2:5:6 ; three Z motors connected to driver outputs 2, 5 and 6
    M671 X-15: 100:215 Y190:-10:190 S0.5 ; leadscrews at rear left, front middle and rear right ; There is and extra space in there on purpose at X-15 b/c unicode chars displaying
    ....
    ....
    ....
    M906 X1000 Y1000 Z0:0:0 E800:800



  • are you using the LPC port? if so the LPC port does not support the M906 command at all.


  • administrators

    @sinned6915 said in Setting Motor Currents- M906:

    I am trying to determine if I can MIX digipot drivers and FW current set drivers on the same system. I am working towards 3 independent Z leveling screws.

    Yes you can. The M906 and M350 settings for the external drivers will be ignored.



  • Thank you gents


 

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