I have four BME280 sensors on GYBMEP modules (common one with 4 pins and with 5 V regulator). I also have BME680 and good analogue hygrometer.
Problem is, all BME280s measures wrong humidity, at least 10-15 % lower. BME680 measures right humidity.
Mostly, I am using Adafruit libraries (address of sensor is changed to 0x76) with ESP32 on I2C bus. Tried another libs, but there were humidity much more wrong. Basic test examples used. Temperature is OK. Tried 3.3 V and 5 V power with no difference.
Anybody any hint? (Yes, may be, buying this not branded modules was not good idea).
How can you connect five devices with two I2C addresses between them to what is presumably a single I2C bus? That alone sounds like a serious problem to me.
Is that one sensor per breakout board? Or one sensor per ESP32 board? You have to be more precise in descriptions.
Are those sensors placed right next to one another when you do the measurements, or at the very least in the same small enclosure? Otherwise there may be drastic local differences in humidity.
wvmarle:
How can you connect five devices with two I2C addresses between them to what is presumably a single I2C bus? That alone sounds like a serious problem to me.
Keep in mind that we didn't know, until seeing the picture in reply #4, that he wasn't using the SPI interface.
RH is measured in several ways ; maybe one sensor corrects for pressure for example, another type doesn’t ( 1 would have expected the 280 and 680 to read the same tho)
You’d need to check this
Another issue is self heating, which can upset the readings - the sensors may need mounting correctly to read the same
I know this thread is quite old, but problem is now here, giving grey hairs...
Today I got finally BME280 (the same as OP) instead of BMP280, and I was so happy. Until getting reads from the sensor. I am pretty sure that temperature and pressure are fine, but humidity is not, for sure. Getting around 20% humidity inside office, with temperature about 22 celcius.
Is there any theories what causes this? Even preath testing about 10 seconds gives max 88%. Is there fake components on these? Or just bad quality parts sold cheaply?
I have this same problem. All of this sensors (BME280, DHT21 or DHT22), it only toys. Good for children. Every of this sensor cannot see propper hummidity. Allways difference is -10% to -20%. In range of check (from 0% -80% hum). Every one is good for mesuring hum between 30-50%. Nothing more. If i must use some of yhi sensor, I allways use hum_offset = +18. This value is check with proffesional calibrate sensor like Testo 174H. I don't want to buy cheap sensor. I have buy some of good, proffesional sensor who cooperate with arduino or esp32. I cannot find any.
