We replaced the mechanical pressure switch of the Pavoni Bart T2 coffee machine with two thermometers, three microcontrollers and a raspberry pi.
See avr/attiny13/ctrl.c for the firmware of the two microcontrollers
responsible for switching the heater on and off depending on the
temperature.
The third micrcontroller lets the raspberry pi communicate with the
other microcontroller. Its firmware can be found in avr/attiny85/mux.c.
