Need to throttle updates?

[joreilly]

I'm using this with Raspberry Pi and Rainbow HAT. If I leave it running the temperature shown steadily increases. It might be case that I need to add heatsink to the processor but wondering if perhaps the code should throttle number of updates it does. Not a big issue in the scheme of things (realise this is just a demo).

[proppy]

@joreilly I think this is coming from the apa102 RGB LED that are just above the temperature sensor.

You could try to dim them off and see if it affect the temperature.

[joreilly]

I commented out code to set LEDs but still seeing temperature steadily going up. I also tried passing in my longer delay (1000000 microseconds for example) to mSensorManager.registerListener() but it didn't seem to take effect.

[proppy]

Pimoroni recently added the following note to the product page

Temperature readings are affected by heat radiated from your Pi’s CPU and the onboard LEDs; calibration can help to correct temperature readings. bstrobl, on the Raspberry Pi forums, suggests to use the formula: corrected temp. = measured temp. - (CPU temp. - measured temp.) / 2. Using a Mini Black HAT Hack3r can also help.

Maybe we could implement that as an helper function in the Rainbow Hat driver

/cc @gguuss

[Emeritus-DarranKelinske]

Here is something to keep the display from flickering with each change. It also converts to Fahrenheit:

private SensorEventListener mTemperatureListener = new SensorEventListener() {
    @Override
    public void onSensorChanged(SensorEvent event) {
        float newTemperature = event.values[0];
        if (Math.abs(newTemperature - mLastTemperature) > 1) {
            mLastTemperature = event.values[0];
            Log.d(TAG, "sensor changed: " + mLastTemperature);
            if (mDisplayMode == DisplayMode.TEMPERATURE) {
                float fahrenheit = 32 + (mLastTemperature * 9 / 5);
                updateDisplay(fahrenheit);
            }
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        Log.d(TAG, "accuracy changed: " + accuracy);
    }
};

[Emeritus-DarranKelinske]

did anyone try the pimoroni suggestion? what were the results?

[msagi]

Pimoroni recently added the following note to the product page

Temperature readings are affected by heat radiated from your Pi’s CPU and the onboard LEDs; calibration can help to correct temperature readings. bstrobl, on the Raspberry Pi forums, suggests to use the formula: corrected temp. = measured temp. - (CPU temp. - measured temp.) / 2. Using a Mini Black HAT Hack3r can also help.

Maybe we could implement that as an helper function in the Rainbow Hat driver

/cc @gguuss

You cannot read the CPU temp on Android Things but even if you could this would not work. I have tried to move the Rainbow Hat away from the Android Things board via a 20cm long 2x20 GPIO cable. The temp sensor still measures data from another reality, e.g. 30C+ at normal room temp. This is a design flaw in the Rainbow Hat itself.