Feature idea (hardware and software necessary)

I have my primo set for passive venting only with the Heater Meter, I've posted pics here before but effectively it is a servo controlling the vent door. It's also fixed in place. It's easy enough to move with my hand when I'm doing something quick like burgers or whatever but I've had a concept to add a switch and a potentiometer to my heater meter which would in effect put the servo in direct control manual mode.

I know how to do this directly with an Arduino and could easily just switch the output the servo receives to an Arduino powered off the same bus but that seems silly given that the HeaterMeter itself is effectively an Arduino.

Direct fan control works but the joystick is a bit cumbersome I find... yeah, yeah, first world problems but let's be honest we're controlling a grill via internet, so that's basically the whole thing here

So I guess the thought would be to add a dedicated switch to toggle between "auto" and "manual" mode and switching to a pot to control the opening when in manual.

Thoughts on difficulty/feasibility/usefulness?

You could easily add a switch that's hooked to the RPi directly and use the GPIOs there with a shell script to toggle the HeaterMeter between Manual and Automatic mode. However, there's no ADC connections available on the HeaterMeter and the Pi doesn't have any at all so it would be tough to add the pot to control it. You could add to the HeaterMeter software to use the Food3 probe connection and make it control the manual output though. I probably wouldn't build it into the default setup though because I don't see this getting much use with other people. I will add it to the TODO list just to keep it in mind, as I do believe the idea has merit even if the hardware can't currently support it.

Thanks Bryan, I probably could hack it to use food probe 3 as I almost never cook more than 2 items at once that I'd use food probes on... naturally the second I finish I'll have a pressing need to use all 3 probes

For my personal setup having extra hardware spread around isn't too big a deal as I'm working on a permanent integrated deal so portability isn't a huge factor. I may just throw a switch between my servo and a spare arduino I have laying around and validate this is as useful as I think it would be.