This project was based on a device done by Denis Tauvel (LINK). I improved the code, leaving the menu design almost the same.

• Arduino IDE >= 1.8
• CMake >= 3.20

• Arduino nano with ATmega168P
• Encoder with a button (or a separate button)
• Two pressure sensors MPX4250PA
• 2x16 LCD with I2C communication (I2C adapter board)

• A0 - pressure sensor
• A1 - pressure sensor
• A4 - I2C SDA
• A5 - I2C SCL
• D2 - encoder A
• D3 - encoder B
• D8 - encoder button

The LCD show two input values in mbar. If both values are the same, then the graph bar is set to 50%, otherwise it will be greater or smaller.

Only first input is used here.

The visible value is a difference between the first input value and the atmospheric pressure value (stored during calibration process).

Only first input is used here.

Lcd shows first input value in mbar and mmHg.

Calibration is done automatically when the device starts. By using this function you will override the previously stored values. The atmospheric pressure and a delta between inputs are stored in the memory. Delta is used to compensate any differences between the sensor readings for the same conditions.

mkdir _build
cd _build/
cmake ..

cd _build
cmake --build .

cd _build
make VacuumMeter_flash