Air Assist Feature - how does it work for MarlinKimbra?

There’s an option to choose air assist, which I assume sends info to set a pin high (or low) at the beginning and end of each job to control the air pump. But, what is it turning on? Is it fan1,2, … or what? Also, I’ve looked at the G-code with air assist turned on and off and there’s no difference. So, just how does this work? How can I take advantage of this feature? I can’t find anything about this anywhere.

It’s quite likely that this function doesn’t do anything at all on Marlin, as there wasn’t a clear thing to connect it to - Marlin already uses the fan output for the laser. If there’s an output you think makes the most sense for this option, let me know - it’s easy to add it.

The MK4 variant has a variable “LASER_PERIPHERALS” in Laser.h for controlling a relay board. It can be mapped to any pin along with a “LASER_PERIPHERALS_STATUS_PIN”. There’s also a “LASER_PERIPHERALS_TIMEOUT” variable set to 30000ms. Hope this helps!

That doesn’t tell me which command would be issued to turn it on and off. :slight_smile: In GRBL, for example, it’s M8 / M9 to turn on / off the air.

I found this in the MK4Duo firmware:

  • M43 T - Toggle pin(s) and report which pin is being toggled
  •             S[pin]  - Start Pin number.   If not given, will default to 0
  •             L[pin]  - End Pin number.   If not given, will default to last pin defined for this board
  •             I       - Flag to ignore MK4duo's pin protection.   Use with caution!!!!
  •             R       - Repeat pulses on each pin this number of times before continueing to next pin
  •             W       - Wait time (in miliseconds) between pulses.  If not given will default to 500

It seems to be a more functional version of M43 that lets you turn a pin on/off. Not sure how to use it.