Air compressor automation designed around of ATMEGA328 and Visuino software, compiled by Arduino IDE.
EEPROM not need programming. After first power ON, select values of Start/Stop and Purge. All values will be automaticaly stored.
The project can be modified according your necessity via Visuino software. Below specifications are adapted to my air compressor.
Install Arduino IDE board support: https://mcudude.github.io/MiniCore/package_MCUdude_MiniCore_index.json and select Internal 8MHz Atmega 328(P) before compiling.

- 8 digits LED Display - easy to read, robust (on board MAX7219 common cathode or external MAX7219)
- Start/Stop adjustable setpoints, EEPROM stored (between 5 ... 10bar).
- Water purging solenoid energized according adjustable start/stop cycles, 2 seconds pulse (display "Purj" ~ romanian abbreviation).
- NO Digital trip input suitable for motor thermal relay or manual emergency shutdown. NC auxiliary contact of thermal relay is connected series with main contactor coil. "Trip" message.
- Support for pressure transmitter 4-20mA or output voltage type
- Zero/Span calibration by variable resistors
- Pressure range 0...12bar, resolution 0.1bar, average filtering
- Spare analog input (maybe air temperature monitoring)
- Spare digital input

Schematic diagram v.1
Atmega328 firmware v.6.6 (flash)
Visuino project 6.6

Fuse bits 8MHz internal



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