ION 901 Watercooler Dumping and reverse engineering repo of the ION 901 watercooler. The microcontroller is a PIC18F6527 PCB Connections DIP switches The switches connect the signal to GND when on. When off, the signals are pulled up. DIP PIN PIC PIN BIT 1 RG0 0 2 RG1 1 3 RG2 2 4 RG3 3 5 RF7 7 6 RG4 4 7 RF6 6 8 RF5 5 Valves Valve PIC PIN Inlet RD0 B (hot) RD1 C (cold) RD2 D (room temp) RD3 Fill RD4 Other Part PIC PIN Buzzer RC2 Compressor RE1 Heater RE2 Mixer RE3 Fan RE0 Reverse engineering notes state_flags Bit Set mask Clear mask Description 0 0x01 0xfe (Re-)booted without power-on reset 1 0x02 0xfd (Re-)booted without watchdog trigger 2 0x04 0xfb used but unknown purpose (wrote something to EEPROM) 3 0x08 0xf7 Water too hot 4 0x10 0xef Fan and compressor running 5 0x20 0xdf used but unknown purpose 6 0x40 0xbf Dispensing something 7 0x80 0x7f Handle compressor interrupt