ESP8266 Community Forum

- Sat Dec 10, 2016 8:00 pm #59338 I also suffer from the false temp readings and had to add a DHT22 to my project to get accurate temps. With the latest changes to the dev branch for nodemcu the humidity is accurate: https://github.com/nodemcu/nodemcu-firm ... s/bme280.c
But the temp gives false readings ~2°C too much. Still somebody investigating this?

- Wed Dec 21, 2016 6:30 am #59782 Still no solution? I did some research on the internet and I believe there are quite a lot of people having this problem!

Would it be an idea to take the module out of the MASTER branch until this is solved?

- Wed Dec 21, 2016 3:53 pm #59802 Using BME-280 with ESP-01 having perfectly plausible results ...

- Fri Dec 30, 2016 10:06 pm #60183 I found this site after googling bme280 calibration temperatures. I have no idea what an ESP8266 is, I'm using a Particle Photon, but I just wanted to add that I'm also having troubles with the BME280. Using a library directly ported from the Arduino library, Temperature looks like it's 2.5-3 degrees C too high, compared to literally every other thermometer in my house, and I have a lot. Humidity is more reasonable, it's only 5% lower than my only other humidity sensor. Pressure is also within 10% of my phone's pressure sensor. But the temperature reading being so far off is just weird.

EDIT: UPDATE! So after googling, I found the datasheet, which says something along the lines of "While the sensor itself is technically accurate to within 0.5°C, there may be some self heating from the nearby processor". Basically the BME280 was designed by someone who didn't realise their own chip was too close to their own sensors, and it throws off the temperature and humidity readings.

Well what do you do when you want a processor to be cooler? You get a fan! Now theoretically, a fan should not affect any thermometer's temperatures - it makes YOU feel cool because your skin is moist, but a dry thermometer should not be affected by a fan, it's just moving air around, not cooling it. Take any of your household thermometers and point a fan at them, and you should not see the temperature change at all. BUT take the BME280 and point a fan at it! Look at that, temperature drops by 2°C! It actually levels off at almost exactly what all the other thermometers in my house read at!

Now having a big fan pointed at the teeny tiny little chip isn't ideal. I also thought it would theoretically lower the humidity since fans tend to dry things out, but for some reason it made my humidity readings RISE to a MORE accurate level. Weird. Either way, next thing I'm going to try is a heatsink. I don't know how I'm going to get a heatsink on such a tiny little chip, but I will find a way.