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Grbl question

Discussion in 'Control Software' started by wvu_kuiken, Oct 12, 2017.

  1. wvu_kuiken


    Mar 18, 2017
    Likes Received:
    I'm wiring an enclosed control box and would like an indicator when i plug my usb in to my arduino and connect to the grbl firmware. I'd like to run a 24v led powered off of a relay from the arduino. Is there a code that I can use in the Grbl config that sets a pin high (send 5v to the relay) once connected to the grbl through grbl panel? I'm now seeing that you can set start up commands through $n in grbl. Is this a route that I can take? If so, can anyone help with the syntax I would use if I'd like to use pin 1 or pin 11 since I won't be using PWM control on the spindle?

  2. phil from seattle


    Mar 17, 2017
    Likes Received:
    Why 24V? With a dropping resistor, you could just run the led off the arduino 5V or one of the output pins.

    Or you could run a 5V relay off the Arduino 5V to switch 24V to the led. Though, that pulls a lot more power. Add in a reversed diode to prevent kickback if you do it that way.

    I understand you want the led to indicate the grbl connection but won't you have ample indication via your PC? I'd just use the Arduino power approach.

    Anyway, there are 3 possible outputs - spindle, mist, flood. you could configure any of those for that purpose. There are M commands for them though spindle has some specific issues iirc. Mist or flood is simpler - M7 - mist and M8 - flood. Mist needs to be config'd in config.h and rebuilt. Pretty easy to do though.

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