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Blackbox 4x v2.4 A3 and A4 pins.

Discussion in 'Controller Boards' started by plasma, Jan 23, 2020.

  1. plasma

    plasma New
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    Hello,
    Could someone tell me please what pond A3 and A4 pins control in the slave motor area.
    Thank you
     

    Attached Files:

  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    That'd be the freshly minted v2.6 boards (I don't even have one yet!) - we will be adding the documentation page and software updates in a week or two, but thats to support a new feature in Grbl 1.1h: Dual axis homing
    See gnea/grbl for details
    gnea/grbl for the compile time options needed to enable it
     
    #2 Peter Van Der Walt, Jan 23, 2020
    Last edited: Jan 23, 2020
  3. plasma

    plasma New
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    Thank you for your reply. Another quest if I may.
    I need to add external driver to drive 6a motor. I know that I can pull the dir/step signal from the slave motor pins. Which pin can I pull (enable+) from. Is this pin 14 on the header?
    Thank you
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Correct, pin 14 of the header between the boards. Or just hardwire your driver's enable (active high or low, tied to vcc or gnd respectively via a 10k resistor) to have it always-on
     
  5. jeffmorris

    jeffmorris Well-Known
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    Will Dual axis homing work on CNC XPro V3 board with external stepper motor drivers? I have dual motors on Y-Axis.
     
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    You need to be able to assign the slave driver's step/dir pins to A3 and A4 pins on the MCU, refer to the Grbl links above

    Big warning though
    a) this is extremely advanced use case - it really is better to BUILD the machine square than relying on the motors pulling it straight (especially working against a frame that is not square to begin with - otherwise undue tensions will just cause issues down the line)
    b) it has compromises (removes Grbl features to make space for this: See gnea/grbl (you loose corexy, spindle direction control, and misting control)
    c) the wiring is a hack - due to the limited IO pins available, the second Y switch is paralleled to Z - refer to the links above
    d) setting up that second limit to make sure it is actually squaring, is quite an exercise, again, actually easier to just build the machine properly (lots of fudging the position of the switch and checking square, and repeat. Quite frustrating to setup)

    All in all, not a feature we advise or recommend for normal users, There are better ways to build a square machine!
    We provide the jumpers for the odd 1% edge cases where someone is retrofitting a machine that has to have it, or something like an Ox or other kind of belt driven machine, where its near impossible to square it up mechanically - so they can use the feature
     
  7. plasma

    plasma New
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    Peter
    I have soldered a wire to pin 14 and ran it to the ENA+ of the external driver. The I ran z axis STEP/DIR to the external driver as well. Connected the motor and it does not work. What am I missing?
     
  8. Metalguru

    Metalguru Veteran
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    Which type of external driver are you using? Are the input signals in pairs? IE Ena+, Ena-. Step+, Step-. Dir+, Dir-?

    If so, you need to either connect all the + pins together to 5v, or all the - pins together to ground, depending on your input signal polarities. IE, if your Step, Dir, and Ena pulses are active high, you connect them to the + pins and ground all the - pins. If they are active low, you connect all the + pins to 5v, and the - pins to the signals. Make sure the signals can drive 5-10 mA because 99% of drivers use optocouplers on the inputs and you need enough current to light the LED's.

    Not sure what polarity of BB pin 14 is.

    MG
     
  9. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Did you compile Grbl with the correct settings:
    I've not used it myself, its a new feature in Grbl, so refer to the Grbl docs linked above
     
  10. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Wait wait what?
    A3/A4 = step/dir
    EN = shared with the other drivers
    Read the Grbl src for details I think you are misunderstanding the feature
     

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