DIY Nitrox Analyzer

Forget about ancient analog potentiometer circuit and build your own digital O2 analyzer based on Arduino compatible board!

Part list
  • Arduino nano compatible board (or any other Arduino board will do)
  • ADS1115 16 Bit DAC Module (the ADS1115 provides 16-bit precision at 860 samples/second over I2C!)
  • LCD 1602 I2C module
  • 1 Push button
  • O2 sensor (I use old cell from my CCR but you can get sensor from Teledyne, Maxtec or other manufacturer)
  • Connector for o2 sensor
Wiring

ADS1115

  • VDD to 5v
  • GND to Ground
  • SCL to A5 (nano)
  • SDA to A4 (nano)

LCD 1602 + I2C module

  • GND to Ground
  • VCC to 5v
  • SCL to A5 (nano)
  • SDA to A4 (nano)

Push button

  • 1 pin to Ground
  • 2 pin to D2 (nano)

Oxygen sensor

  • positive to A0 ADS1115
  • negative to A1 ADS1115

The source

o2_analyzer.ino

Additional library require.

The code is very simple. Calibration and storing millivolt output from o2 sensor (in the air – o2 20.9%) when button is pressed.

Oxygen percentage and millivolt of sensor will display on LCD.

Note
  • In many case i2c device address are different from the code. If something  not working then check your i2c address (ads1115 and lcd module) using i2c scanner.
Update 28th Feb 2017
  • Reading sensor function changed from Single Ended to Differential Conversion. Sensor out should be connected to A0 & A1 (ads1115) accordingly.
Update 22th Feb 2017
  • Button need push & hold for 2 sec to calibration.
  • Display MOD (Maximum Operating Depth) : po2 1.4 & 1.6

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