BME680: GAS Resistance is always the same

[lisa999]

The measured gas resistance starts low for a new BME680, then it increases until it is always the same. This value then never changes again, any suggestion where this is comming from is appriciated. I've seen this behaviour now at two bme680's. The temperature, humidity and pressure are changing almost every measurement.

Init values used (in python): 

sensor.set_humidity_oversample(bme680.OS_2X)
sensor.set_pressure_oversample(bme680.OS_4X)
sensor.set_temperature_oversample(bme680.OS_8X)
sensor.set_filter(bme680.FILTER_SIZE_3)

sensor.set_gas_status(bme680.ENABLE_GAS_MEAS)
sensor.set_gas_heater_temperature(320)
sensor.set_gas_heater_duration(150)
sensor.select_gas_heater_profile(0)

sensor.get_sensor_data()

sensor.data.gas_stable
True

"{} C, {} hPa, {} RH, {} RES,".format(sensor.data.temperature,sensor.data.pressure,sensor.data.humidity,sensor.data.gas_resistance)

'25.79 C, 1024.7 hPa, 32.167 RH, 9186214.0 RES,'

'25.76 C, 1024.7 hPa, 37.694 RH, 9186214.0 RES,'

'25.74 C, 1024.72 hPa, 37.636 RH, 9186214.0 RES,'

And so on...

[handytech]

Is this behavior seen on only one or multiple sensors? Have you built/assembled custom PCBs or a BME680 shuttle board?

Please confirm that the gas sensor configuration is correct (both values and bus transaction). We typically recommended running known code first, but we currently provide C-code only.

If the resistance values reaches its maximum value, it is often a sign of assembly or integration issues. Please make sure that you follow the instructions in BME680's HSMI manual.