Ask HN: Do you know of a good open-source microwave oven firmware?

Short story long: My microwave has a terrible control panel and now the very custom and highly integrated rotary encoder broke and I can't set time and wattage anymore.

Pretty much all microwave ovens work the same way, you need a relay to turn on the magnetron, and one for the light bulb, a few buttons to set time and wattage, and a few pins for the segment display.

I am surprised that I couldn't easily find a generic microwave firmware for arduino boards..

Do I have to write this myself ?