DIY Nitrox Analyzer (Arduino based)

[zebu14]

The part that's responsible for displaying everything on screen, and the menu structure, won't be open-source since it'll have some brand logos in it.

The "menu" part is the one I am not confident with...
I will have to learn that part !

 

[Wouter D'Haeseleer]

Just wanted to share my project as well: netdata-be/nitrox_analyser

Some highlights:

• Custom PCB for the components
• Auto-calibrate on air
• Auto-calibrate on pure o2 ( at boot it calibrate to air, if the measured mV is within 10% of the expected linear 100% o2 voltage and you trigger a manual calibrate, it will recognize this as a second gas to calibrate, this way we correct for the linear offset of the cell )
• Multiple display modes
• Battery monitor
• Saves the display modes to memory so it remembers the last one used
• Display stanza conver

 

[aschouw]

Just wanted to share my project as well: netdata-be/nitrox_analyser

This looks really nice.
I have built it now, but I'm having a couple of problems.
The first is that the digits for the O2% are overlapping. It works if i change it to a tiny font. I would have thought it was a problem with the U8x8 library, but it obviously works in your pictures @Wouter D'Haeseleer .
The other problem is that I can't get the push button to work. The analyzer randomly swithes between the screen modes, and calibration, and pushing the button does nothing. I have wired it up as described in your diagrams, except the battery circuit.
Any suggestions as to what might be my problem?

 

[Miyaru]

Are you sure you have a SH1106 display as used by Wouter? SSD1306 displays look the same, but require a different library and/or initialization.

 

[aschouw]

On closer scrutiny I see that I do indeed have a SSD1306 display. Thank you @Miyaru .

 

[Miyaru]

On closer scrutiny I see that I do indeed have a SSD1306 display. Thank you @Miyaru .

Change line 41 to

U8X8_SSD1306_128X64_NONAME_HW_I2C u8x8(/* reset=*/ U8X8_PIN_NONE);

and check if that solves the issue. If not, check the specs from your display and look up that type in the library.

 

[aschouw]

Change line 41 to

U8X8_SSD1306_128X64_NONAME_HW_I2C u8x8(/* reset=*/ U8X8_PIN_NONE);

and check if that solves the issue. If not, check the specs from your display and look up that type in the library.

That didn't solve it unfortunately. I don't have the specs for this display, so it's a bit hard to look up. I think I'll just get a different one. I would like it to be a little larger than the 0.96" I have now anyway.

 

[aschouw]

Finally got a SH1106 display now, and the problem is exactly the same. Weird.

 

[Alurpal]

Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout

Give your next sensor project a nose for gasses with the Adafruit MiCS-5524 Gas Sensor Breakout. This breakout makes it easy to use this nice sensor from SGX Sensortech. The MiCS-5524 is a ...

www.adafruit.com

Any thoughts on using this as a CO sensor?

 

[Miyaru]

Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout

Give your next sensor project a nose for gasses with the Adafruit MiCS-5524 Gas Sensor Breakout. This breakout makes it easy to use this nice sensor from SGX Sensortech. The MiCS-5524 is a ...

www.adafruit.com

Any thoughts on using this as a CO sensor?

Requires calibration, so bump gas is required. And it's not a sensor I would use for my own breathing gas.