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.

• Adafruit ADS1015
• running Average (zip file)
• DFRobot I2C LCD

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