Two extruders w/PID control and two part fans - Possible on RAMPS 1.4?


I'm planning to use a RAMPS 1.4 board for my CoreXY printer.
I've spotted the fan extension header allowing me to add two more PWM controlled fans (one for each extruder), and when going through the firmware configuration tool online, I saw that enabling PID requires a spare PWM module timer to operate.

My question is, is it possible to operate two Extruder heaters on the normal 5A mosfets, with PID, and also have two independent fans controlled with another two PWM enabled pins?

Many thanks,


  • Firmware uses no timers for PWM. PWM is software simulated so there is no timer->PWM problem.

    Just be aware that slicers only create gcode to support one fan. So if you speak about pla cooling fans you should have only one or one output with 2 fans if you like.

    If you talk about extruder cooling fans like used in full metal extruders, that is no problem.
  • Thanks. Very helpful answer!

    Good point about the lack of multiple fan support; I hadn't noticed that. I'll probably now put them in parallel and use the spare output for the hotend heatsink cooling fans so they can be temperature controlled.

    Thanks again.
  • Latest firmware can handle 2 fans using P0/P1 in M106 but still slicers will not support it, so that does not really help:-(
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