ESP8266 Community Forum

- Thu May 11, 2017 6:25 am #65832 I have two different AM2320 temperature and humidity sensors. I am finding the temperature reading is about what it should be, but the humidity is out significantly. It is reading 39.3%, but it should be reading around 65%.

I am using the https://github.com/thakshak/AM2320/ library.
(note I left the issue report in Github about this)
Using a NodeMCU.

I have various other temperature and humidity sensors to obtain the 65% result from. These include AM2302 and BME280.

Unfortunately these sensors are not very popular, so not many people will find the same problem. Having said that I noticed many listings on AliExpress for the AM2320 state that it is replacement for the AM2302. Well it certainly isn't a drop in replacement, but I suppose any T/H sensor can be considered a replacement.

I saw one other person on another forum with a similar problem. Any suggestions regarding the humidity readings?

- Thu May 11, 2017 8:32 am #65836 from my experience these sensors are very sensitive to power fluctuations.
If you do measurements during wifi operations and your powerrail decoupling is not up to par you get worng results.
The lower limit of 3.1V is very optimistic, too. Make sure you have rock stable 3.3V and you should get reliable results.

- Thu May 11, 2017 5:04 pm #65850

from my experience these sensors are very sensitive to power fluctuations.
If you do measurements during wifi operations and your powerrail decoupling is not up to par you get worng results.
The lower limit of 3.1V is very optimistic, too. Make sure you have rock stable 3.3V and you should get reliable results.

Thank you for suggestion.
Do you think the AM2320 is more sensitive than the AM2302?

I doubt power fluctuations is the problem as the temperature measurement is very accurate. I don't think the code was actually using any wifi operations, but I will double check this. I will also try some extra power decoupling.

The power regulation on the NodeMCU is generally very good, which is why have been using them for testing set ups. I gave up doing test setups on the ESP-01 because of the problems with power sensitivity.

- Fri May 12, 2017 7:55 pm #65871 I put a 1000uF capacity on the power supply to the AM2320, but it made no difference to the humidity readings.