Duet WiFi Additional Stepper Drivers with SPI



  • Hey guys,

    I want to add 2 Stepper drivers to my Duet WiFi. I know I can Just use the DUEX2 but that is Overkill because I only Need the drivers.

    What is the simplest was to so that? Preferably in a way that the WiFi can Talk to the drivers over spi.
    What is the easiest way to do so?
    Can I use the breakout Board or can I "Just" Connect additional drivers to the Expansion Header?

    How would you do that?

    Greets
    Max


  • administrators

    The only SPI-controlled drivers supported by the Duet 2 build of RRF is the TMC2660. There are a few TMC2660-based single driver boards, for example the TMC2660-BOB.

    There are a couple of complications with using TMC2660 breakout boards instead of the DueX2. First, RRF assumes that the sense resistors are 0.05 ohms. If your breakout boards use different value sense resistors, the motor current you set will be scaled accordingly. Second, unless RRF detects that a DueX board is present, it will assume that any additional drivers are not addressable via SPI. The simplest way to fix that is to compile the firmware yourself, changing the line in file Platform.cpp that sets the value of numSmartDrivers.

    Alternatively you can use non-SPI controlled driver modules.



  • @dc42 said in Duet WiFi Additional Stepper Drivers with SPI:

    Alternatively you can use non-SPI controlled driver modules.

    TMC2130s were Trinamic's transition from jumpers to SPI. They do both. It not quite as nice as full SPI control, but very close, to use 2130s with just jumpers and the pot for current, and therefore they'd only need step/dir/enable from the expander.



  • Thanks for your response!

    For the time beeing I'll try some drivers I have laying around (without SPI) to just test it....maybe later on I'll return to the SPI-question. Mostly because I don't know how to compile duet firmware on my own and have to read that up 🙂

    Have a nice day,
    Max


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