BMP280 sensor accuracy

[AnnaB]

Hello! We have problems with BMP280 accuracy..The datasheet indicates that the typical (or 1-sigma) absolute accuracy of BMP280 is +/-1hPa from 300 ~ 1100hPa under the temperature 0 ~ 65C. So min/max accuracy is +/-3hPa (3-sigma).

Out of the 1415 BMP280 units soldered to the PCBs, 1390 units (or 98%) show a deviation from the calibrated reference +3 ... + 6 hPa, which exceeds the 3-sigma accuracy range (+/- 3 hPa). The data is visualized in the attached pics. Our reference of ambient pressure value is the Nesa BAR-AV calibrated high precision barometer (0.15 hPa accuracy).

We compared the soldering profiles with the specification and found no discrepancies..

What could be the reason for such problems?

BR,  Anna

  

[AnnaB]

Hello again! The question is 

Does the BMP280 have a linear response to changes in atmospheric pressure? Can we implement a correction to the measurement of the ambient point?There is no information in the datasheet.

BR, Anna

[BSTRobin]

Hello AnnaB,

BMP280 is used to measure barometer, the test results are approximately linear with the actual air pressure. But at the same air pressure point, it will be affected by temperature. The data sheet contains the description of compensation, and the sensor API contains the compensation code.

For your issue, if you confirm that your hardware complies with the HSMI specification, you need to keep the same software with the reference code software, and then look at the test results.
https://www.bosch-sensortec.com/media/boschsensortec/downloads/handling_soldering_mounting_instructi...

[FAE_CA1]

Hi AnnaB,

Thanks for your inquiry.

BMP280 has min/max absolute accuracy of +/-3hPa in the range from 300hPa to 1100hPa and from 0C to +65C. However, after soldering BMP280 on PCB there will be mechanical stress applied to BMP280 so that the offset may have changed. In order to get better accuracy you can do end-of-line calibration in your production line with a reference pressure meter. You can then save the offset of each BMP280 into the processor's flash memory and apply the offset to all future measurements. Then all your units will have accuracy within the typical range of +/-1hPa after end-of-line calibration.

Please see the attached "BST-BMP280-AN005-03_end_of_line_calibration.pdf" for more information.

Thanks.