This is nitrox analyzer based on Arduino compatible board derived from the works of ejlabs/arduino-nitrox-analyzer https://ejlabs.net/arduino-oled-nitrox-analyzer/
This fork will be building out the documentation of and capability of the analyzer over time and updating the code for different hardware configurations as well as bringing all build information under one roof as it seems the original author has not updated in quite some time. Rather than to lose the original design and code I believe in the spirit of the release it should be brought here for posterity with all credit of the original work given to ejlabs.
I know there will be some flak in the diving community about a project of this nature. The original project was featured on Hackaday.com and many people complained about
the hazards of using a DIY project for testing the O2 in a tank. The sensor is the most important component in the system; if you buy a cheap or faulty sensor you will
likely have issues and be at risk. However the only thing the name brand meters are doing is reading a voltage generated by a similar sensor, doing a calculation based
on the voltage, and then displaying a reading. If you had a very sensitive multimeter and a calculator you could do all of this manually using only the oxygen sensor.
In this case rather than using a premade chip that is doing the calculation on the fly while only displaying the O2 content we are using a board that can do a few more
functions and display it on a small screen. Can the board mess up, sure but as with all things the biggest safety is that squishy mass of tissue between your ears.
If the meter does not read 20.9 percent O2 at sea level and the tank shows 32 percent O2 on the label and the meter does not read somewhere fairly close to that more than
likely something is wrong. This is literally the same thing you have to consider when using a meter that is commercially made, you either scrap the dive (which hopefully
you did check your tank before leaving the shop so that would not be a true issue) or you use an alternative meter (which a shop providing Nitrox should have or every
other person in the group should have.)
As with all things this project is provided AS-IS with no warranty whatsoever, it is a DIY project so please use your head when utilizing it.
Parts list: Arduino board compatible with the I2C protocol --- ADS1115 compatible DAC --- SSD1306 compatible display (128 X 64 preferred) --- A toggle or locking switch for main power on --- A monetary push button for controlling functions --- A battery to supply power for the Arduino (5v to 6V is best but reference your boards vin range) --- Oxygen sensor (An aftermarket Teledyne R22S or compatible would be recommended. If you want to connect your sensor remotely a Teledyne R17S or compatible along with a cord and jack for plugging it in.) --- Wiring for making connections --- A hobby box for enclosing the project --- A Piezo Electric speaker (Optional) ---
This is a work in progress, more information will be added