Telaire T6613 Support

[james-coder]

Telaire T6613 is a UART CO2 sensor that comes integrated into some other Telaire devices like Telaire T8100. (Available on ebay for $35 to $100: https://www.ebay.com/sch/i.html?_nkw=telaire+t8100)
Use J2 (the white 0.1" header) for 5V/TX/RX/GND, it connects to the T6613.

Datasheet: https://www.amphenol-sensors.com/en/component/edocman/295-telaire-t6613-t6615-co2-sensor-development-kit-user-manual/download?Itemid=8486

It has a CO2 sensor with +/- 75 ppm accuracy.

This library was based on copying bits from MHZ19 CO2 sensor code.

I've tested it here with a generic ESP8266 dev board connected to Telaire T8100 (with T6613 module.)

The black wire below is me using ground for TX/RX/GND as I was powering it with another 5V/GND adapter.

[mcspr]

Thanks! Perhaps description for this should also be added as a Wiki page?

[james-coder]

Added to Wiki: https://github.com/xoseperez/espurna/wiki/Sensors#t6613-co2-sensor

[james-coder]

Sensor PDF says "max 2000ppm", but I just tried rebuilding/ota reflashing and got "Out of range" in my room. (Should I be concerned about the high CO2 value? 😆 Opening a window now.) I bumped it up to 5000 and rebuilt / ota-ed and sure enough now it reads 2397ppm.

[mcspr]

Elevation setting? Or maybe calibration is a bit off.

There are still some commands left over to check for current mode / status, set / get elevation (+-500ft, from 0 to 5000) and check / do calibrations

[james-coder]

It would be nice to expose the elevation offset command, maybe through the web interface if possible. (Not sure how that works yet.) Calibration is ABC Logic done automatically (assuming the earth stays at 400ppm 😆 I think engineers weren't thinking even a decade or two away? My local university already says outside air is 420ppm, not 400ppm.) unless you can get your hands on some CO2 gas / known concentrations to enter a fixed calibration. I'm not sure if there's a way to turn on / off ABC Logic, that spec sheet seems confusing about that. (It might be the exact same way as the MHZ19, since now I realize the MHZ19 is basically a rip-off version of the T6613. 😆)

[james-coder]

Or the T6613 is very voltage sensitive and I started giving it 4.45V instead of 4.95V when I change esp 8266 boards. (Wemos D1 Mini has a pin labeled "5V", but I guess it really means "Not Quite 5V", as it's in-line with a diode.)
My CO2 levels have returned to normal. (It matches another CO2 meter I have set up next to it.)

[mcspr]

Auto-calibration as described is veeery dependent on proper ventilation, so it might not always be right, but I guess you sorted that out anyway with a different way to power it.