When the hts221 passes the test, the humidity of the constant temperature and humidity box is adjusted to above 70% (the temperature of the constant temperature and humidity box is not set to a specific degree), which is very inaccurate.
In particular, when the constant temperature and humidity box is adjusted from 99% to 50%, the humidity value is stabilized at 50%, 4 hours or even 8 hours, the value read by hts221 is still 99%.
Tested four consecutive hts221, this is the case.
And my hts221 code, use the following code:
https://github.com/STMicroelectronics/STMems_Standard_C_drivers/tree/master/hts221_STdC
