Enviro pHAt: How precise is it?

albin2008 · April 18, 2018, 8:16pm

Hello.

Me and my Team are using the Enviro pHat for an experiment, so that we can write a paper in physics Class.
I wanted to ask if anybody knows how precisely this Sensor can measure the G values, the Height and the pressure Level.

Thanks for the help

Greetings from Switzerland

gadgetoid · April 19, 2018, 9:04am

The accelerometer and magnetometer is the LSM303D, which you can find full specifications for here: http://www.st.com/resource/en/datasheet/lsm303d.pdf (you probably want page 10)

The temperature and pressure are measured by the BMP280, which you can find specifications for here: https://cdn-shop.adafruit.com/datasheets/BST-BMP280-DS001-11.pdf

Note that if you plan to calculate altitude, it would be determined by measuring the pressure and calculating an offset from a supplied sea level pressure value. It’s only as accurate as the offset you supply.

The built-in calculation is here:

github.com

pimoroni/enviro-phat/blob/614419a9a225687798a4a46c622a2b63953daddb/library/envirophat/bmp280.py#L154-L160


def altitude(self, qnh=QNH):
    """Return the current approximate altitude.


    :param qnh: Your local value for atmospheric pressure adjusted to sea level.


    """
    return 44330.0 * (1.0 - pow(self.pressure() / (qnh*100), (1.0/5.255))) # Calculate altitute from pressure & qnh

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Enviro pHAt: How precise is it?

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