BME280 Temp & RH accuracy

[simonk]

Hi everyone,

We have designed some kind of a industrial sensor using two of your BME280 sensor on the same board for measurment of ambient and sorrounding contitions. We have made a test batch of more than 100 pcs and compared readings with calibrated sensors.

We are constantly getting to low readings for temperature and relative humidity compared with reference sensors. Deviation is between -0.1 to -0.9°C for temperature and -2 to -4 or even -5% for relative humidity compared to reference sensors. All that at normal room conditions. 

Do you have any idea what is the reason for this? I can provide data excel sheet if needed.

Many thanks for you answer.

[Jet]

Hi Sir:

    Before your measurements, did you calibrate temperature and humdity?

   Calibration shoud be done after soldering to pcb board.

[simonk]

Dear Jet,

I am so sorry, but I do not understand you proposal. 

Did you mean Reconditioning? Dry-baking & re-hydration was not performed after reflow. Before sensors were used, there were at least 2-3 days at ambient conditions... But we can try to follow Reconditioning Procedure next time. 

[Jet]

Hi Sir:

     Did you know what is calibration of sensor and how to calibrate a sensor?

    Actually after soldering, calibration must be done in order to get more accurate data.

[simonk]

Dear Jet,

I know what calibration means, but how to perform it on BME280 sensor? Sensor itself has some read-only calibration parameters, that are used during calculation of all readings and with them sensor readings should be within specifications? 

Or did you mean that we need to do additional compensation (aka "calibration") on our microcontroller/application? But this would mean at least 3-point calibration in climate chamber.

We will use Reconditioning Procedure (nr. 1) next time and compare results. If we could get within specified accuracy it would be acceptable for us. 

Many thank for your ideas/proposals

Simon