DIY Touch Screen Trimix Analyser

[stevetto]

Nitrox analysis

 

[Miyaru]

ESP32 is much powerful than arduino nano but the lcd refreshing is still challanging.

Consider creating the entire screen in memory, and finally writing the memory contents to the display. If you have any flickering with text, this will solve it as well. Keywords: sprite. There's a library out there for TFT displays: TFT-eSprite and is probably useful for your touchscreen as well.

 

[happy-diver]

I just love what smart motivated people do!

Thank you!

 

[stevetto]

Consider creating the entire screen in memory, and finally writing the memory contents to the display. If you have any flickering with text, this will solve it as well. Keywords: sprite. There's a library out there for TFT displays: TFT-eSprite and is probably useful for your touchscreen as well.

Thank you for the info, I will check it.
I do not refresh the whole screen, only characters and their background.
So there is no flickering.

mp4: analyzer.mp4

 

[KDAD]

It has not been calibrated to Helium.
For nitrox I use 3 points calibration.

View attachment 653218

For the 3-point Nitrox calibration, how are you doing the 0% O2? Saturating with N2 or is it an electrical zero?

 

[stevetto]

For the 3-point Nitrox calibration, how are you doing the 0% O2? Saturating with N2 or is it an electrical zero?

You can use N2, but most probably Argon or Helium is easier to access for divers.
If you disconnect the O2 sensor you can also calibrate it electrically to zero. But it is less accurate.

 

[stevetto]

Calibration with 100% O2 and then measuring EAN32

 

[JahJahwarrior]

This is a very nice project, are you selling the components that are custom on your website?
Would you consider adding a CO sensor as well? The parts are relatively cheap, you can use the same one that CooTwo used, and there is nothing on the market that has three in one.

 

[stevetto]

This is a very nice project, are you selling the components that are custom on your website?
Would you consider adding a CO sensor as well? The parts are relatively cheap, you can use the same one that CooTwo used, and there is nothing on the market that has three in one.

Components on my website are much more professional than this analyzer, mostly cnc machined parts or contains only high quality industrial grade components.
Some of them is in stock and some of them made on request. Let me know in pm if you are interested in any of them. But this is another story.......

This analyzer is only a hobby project, I just wanted to see if I can make an analyzer with such functions I have not seen before. Like the calculation of MOD for different pO2 based on the measured gas concentration, the voltage measured by the sensors and graphically see the response curve of the sensors.......

Before adding the CO sensor I would like to see how accurate it is for trimix. The calibration process of this device can detect the real non-linear response curve of the He sensor. Which is not documented anywhere and the manufacturer could not give me. (I do not make the compensation with fixed values at different He/O2 concentrations, compensation based on the response of the specific sensor). But unfortunately I do not have access for pure He nearby me. For the tests and programming I used ballon gas, but that is not pure He (min. 95% + other ingredients). So it needs He calibration. Than I would like to compare the measurements to Divesoft.

I do not know Cootwo. Can you tell me which CO sensor is used in it?

 

[Jarek Andrzejewski]

I think MOD calculated using O2 % is standard function of any analyser with processor, e.g. see https://www.greisinger.de/files/upload/en/produkte/bda/GOX100T_EN.pdf (page 4-5).
I did such option in mine, too (never finished, I stuck to simple voltmeter-like with potentiometer calibration, as I really use standard mixes anyway):