Re: ESP8266 - BME280 Sensor Readings Wrong
Posted: Tue Mar 15, 2016 9:18 am
BME280 has a humidity absolute tolerance of +/-3%. The HTU21D has a humidity absolute tolerance of +/-2%. Without knowing the actual real RH value, they could in theory read 5% different values and still be within specification.
Humidity is always going to be a measurement without a great deal of accuracy, especially in low cost sensors.
For temp, BME280 is +/- 0.5C @ 25C and upto +/- 1.0C over the full range of temps. HTU21D is +/- 0.3C.
The HTU21D is a more accurate sensor, but doesn't do atmospheric pressure.
Given that the devices are physically in different locations in free air, there is a good possibility that the temperature *is* actually different by half a degree. It doesn't take much to change the temp by a small amount. All of your readings appear to be within tolerance given the circumstances.
Humidity is always going to be a measurement without a great deal of accuracy, especially in low cost sensors.
For temp, BME280 is +/- 0.5C @ 25C and upto +/- 1.0C over the full range of temps. HTU21D is +/- 0.3C.
The HTU21D is a more accurate sensor, but doesn't do atmospheric pressure.
Given that the devices are physically in different locations in free air, there is a good possibility that the temperature *is* actually different by half a degree. It doesn't take much to change the temp by a small amount. All of your readings appear to be within tolerance given the circumstances.