Humidity and pressure seems way off the for the very first read

[leinardi]

For the very first reading I'm getting values of humidity and pressure very different from the successive readings.

For example, with this code:

BME280 bme280 = new BME280(BoardDefaults.getI2CPort(), 0x76);
bme280.setSamplingWeatherStation();
for (int i = 0; i < 10; i++) {
    float[] floats = bme280.readAll();
    Log.i(TAG, String.format(Locale.getDefault(), "Temp: %.1f°C, Humidity: %.0f%%, Pressure %.0f hPa", floats[0], floats[1], floats[2]));
}

I'm getting this output:

I/TemperatureActivity: Temp: 22,1°C, Humidity: 27%, Pressure 735 hPa
I/TemperatureActivity: Temp: 22,5°C, Humidity: 33%, Pressure 971 hPa
I/chatty: uid=10039(com.example.androidthings.driversamples) identical 1 line
I/TemperatureActivity: Temp: 22,5°C, Humidity: 33%, Pressure 971 hPa
I/TemperatureActivity: Temp: 22,5°C, Humidity: 33%, Pressure 971 hPa
I/chatty: uid=10039(com.example.androidthings.driversamples) identical 4 lines
I/TemperatureActivity: Temp: 22,5°C, Humidity: 33%, Pressure 971 hPa

Is this behavior intended? Should I manually do multiple readings and discard the firsts?

[knobtviker]

This behavior is exactly the reason I wrote this fork of contrib-driver. Usually, I don't instance these drivers directly but with *UserDriver class. I'll test and research what is going on, I suspect first value released is read faster than buri in time of the hardware itself.

[leinardi]

For my specific use case I need only one reading of all 3 values every 5 min, so the sensor manager seems too complex and wasteful of resources (I would need 3 separate DynamicSensorCallback() that are going to poll several time per seconds each), when, accessing directly the sensor, I should be able to do only the reads I really need.

If the problem is only the first read, maybe you can call a readAll() at the end of the connect(), so that the wrong readings are discarded. This is a workaround, not a fix, but should work until is properly fixed.