I’m working in a project to monitoring air quality using a Air Quality 5 click from Mikroelectronika (it has an MiCS-6814 sensor) and a Raspberry Pi 3B+.
I have used the Pimoroni library for enviroplus (https://learn.pimoroni.com/tutorial/sandyj/getting-started-with-enviro-plus) and now I’m reading some values for Oxidising, Reducing and NH3 based in the Gas.py example in the library.
I have some questions about it and I would greatly appreciate if you could help me with that:
The code of the Gas.py example has lines to get the resistance value for each gas as follow:
try: ox = (ox * 56000) / (3.3 - ox) except ZeroDivisionError: ox = 0
and the same for other two gases. A question is that “56000” must be modified to get the right resistance values?
on the other hand, I’m reading the 3 resistance values (Ox, Red and NH3) and I’d like to convert that values to ppm for each gas but I can’t find the right expression to do it.
I’m confused if the resistance that I read in the example code is Rs, R0 or (Rs/R0) ratio.
I would highly appreciate if you can give me some information about it.
The project send data by MQTT to Ubidots bus it is working good.
Thank you so much,