I got the Enviro+ running with a Raspberry Pi Zero but the data is too unreliable to realistically contribute to a Citizen Science project like Luftdaten.info. It’s a great form-factor, but when you click the sensor board directly on the RPI Zero W, both CPU-temperature and RH humidity sensor data are too high.
I wrote a script that logs CPU and sensor temp to a csv file every 30 seconds and ran that with a direct setup and a setup with a 10cm flat cable. Turns out that if you directly connect it, the CPU heats up some 6 degrees more as well and uncorrected temperature shows 9-10 C too high. With a ribbon cable, temperature looks better, but still ~1 degree too high according to other thermometers.
Same goes for relative humidity, too high a temperature shows lower %RH of course. With the ribbon cable it still shows too low a value. I see several posts about this on the forum, but haven’t seen the final solution other than compensate it with the script. Either use a ribbon cable or fan, basically killing the great form factor.
Two main questions here:
- I can’t find any replies from pimoroni, did I miss something here? Contributing to citizen science projects should be done with reliable data. Are there any pending changes in either the libraries or a new hardware model?
- While you can do some correction for the temperature, based on the CPU reading, the humidity is still an issue. With the ribbon cable I get slightly better values, but still 5-10% too low. Anyone has the magic formula to correct that?
PS: if the data from my board is so far off that it’s just faulty, that’s a good answer as well and I’ll get back to my supplier :-)