Implementing chamber temperature control on MK4  

Implementing chamber temperature control on MK4

I’m designing an enclosure for my MK4, with the primary goals of air filtration (recirculating, not exhausting to outside), temperature control (thermometer, heat scavenged from the bed, cool air from outside via fan), and “volume control”, meaning it’s going to be a lot smaller than the official enclosure, at least in the front where there’s nothing protruding from the sides or cable management needed.

Anyway, as I was contemplating temperature control, I noticed PrusaSlicer’s expert mode “Chamber temperature” setting, saved with each filament profile, and thought it would be really nice to leverage that.

For software, I imagine I’ll probably need to make custom fw, to consume whatever gcode that “chamber temperature” translates into, and add a PID loop using input from a thermometer and output to PWM control a fan.

But what about hardware? How would I go about connecting a thermometer (input) and a fan (PWM output) to the MK4’s mainboard? Is this the kind of mod for which the “GPIO hackerboard” exists?

I suppose worst case I could move all I/O to a dedicated PID controller dedicated to chamber temperature control, communicating with the MK4 via I2C (which I think the hackerboard allows), but I’d rather just use the MK4’s processor if at all possible.

Any pointers are appreciated, thank you for reading.