bme688 pressure and humidity readings zero. takes two weeks for gas sensor to auto-calibrate.

[garberw]

I have a bosch bme688 sensor from adafruit. it is new. the pressure and humidity are reading zero. when will it be burned-in? It has been running 14 hours. Is it contaminated meaning someone mistakenly touched it? Is there any way to fix it or just wait? I also have a second bme688. That one took two weeks for the gas sensor to reach auto-calibration. Is this normal?  I read in another post that it auto-calibrated after 500,000 measurements.  My sensor is read every 15 seconds which means 4x/min * 60 min * 24 hr * 14 days = 81000 measurements for mine to equilibrate.  So waiting may fix the gas sensor but I am not so sure it will fix the pressure and humidity readings.

[BSTRobin]

Hi garberw,

When you test BME688, what is the surrounding working environment?
Is the supply voltage stable?
Can host read BME688 chip ID when the pressure and humidity readings are zero?

[garberw]

the surrounding environment is a 15cm x 15cm enclosure with holes and it has a stable power supply.  I swapped that breakout board for an identical one and it is working now but I would like to know what was wrong with the first bme688.  The first one had working temperature but pressure and humidity were zero.  I had another (third) sensor which had a similar behavior and after a period of a few days it magically started working.  I assumed it was contaminated but the contamination was "burned in" or "burned off" or evaporated.  It looks like the present  one will reach equilibrium gas resistance near 1 Meg Ohm in another 5 to 10 days.  The present one has all other sensors working fine out of the box.  I am not sure how to read the sensor ID.

[garberw]

I would like to add that what can appear as spikes in the readings may be due to discrepancies between any real time clock (RTC) and the clock of the (weather server) computer reading the MCU (e.g. arduino).

[BSTRobin]

Hi garberw,

For Adafruit hardware board, you have to check it with the supplier you bought.

For BME688 software, you could download it from https://www.bosch-sensortec.com/software-tools/software/bme688-software/