I am using 4 BME688 on a board we designed for the ESP32. The sensors are read using SPI.
My software is based on the Bosch Parallel-mode example -- measuring 10 steps with a wait time of 6 seconds per each step.
2 of my sensors perform well. The remaining 2 return a fixed Gas-resist value of 5684.8 for ALL of the steps. One of those sensors also returns a bad pressure result.
I have this similar phenomemnon on several of these boards. I also have boards where all 4 sensors perform well -- so this is not a board-design issue.
I also had a phenomemnon were a specific sensor seemed to perform well and then in some instances, sporadically (no rule to it), also gave me this same 5684.8 Gas-resist value in one or more steps.
I couldn't find anything about this in the data sheet.
Has anybody else seen this phenomenon?
Can anyone provide an explanation -- or suggestion what can be done to fix this?
I attach a sample measurement of the 4 sensors, labeled BME0 - BME3:
First 2 sensors are good:
You can run the force mode example first to access a single sensor, such as "BME: 2" or "BME: 3". If the pressure and resistance values are normal, then the hardware is OK, and you need to check the software code.