BMP280 temperature compensation problems

[mliszewski]

We can't find constant dependence of pressure in temperature function. Every BMP280 behaves differently. We are using this sensor for altitude measurement. We are using reference sensor and it works quite well when both sensors are calibrated and stays in the same temperature range, but it's unpredictible when temperature changes. We tested 5-6 different BMP280s and can't find dependence between pressure and temperature. We are using compensation functions from datasheet.

[Yanchao]

Hi,

Have you make offset calibration before find dependence between pressure and temperature? The BMP280 is delivered in a completely calibrated form. However, the soldering and assembling process generates additional offsets.

After offset calibration, 5-6 pcs pressure sensor output almost same, then you can make some comparision.

Best regards.

[mliszewski]

Thanks for your answer. I am not talking about constant offset for each sensor, we have implemented it already. I am talking about unstable pressure value change when temperature change on different sensors. We can't detect common characteristic.

[Yanchao]

Ok. I got your question.

For bst-bmp280-ds001.pdf , TCO(offset temperature coefficient) is +/- 1.5Pa/K. If your test result is different, pleae provide test data and test procedure. We could make further analysis.

Best regards.

[mliszewski]

Results of our tests can be found in attachment.

Colors in graph:
Red(heating)/orange(cooling) - 1st BMP280
Dark Green(heating)/Light Green(cooling) - 2nd BMP280
Dark Blue(heating)/Light Blue(cooling) = 3rd BMP280

0 at X Axis equals 24 Celcius degrees.

As you can see each sensor has different characteristic and there is no constant dependency. Ignore offsets- they are not the problem here.