Read temperature and pressure from Bosch BMP180, BMP280, BME280, and BME680 sensors in Elixir.
Here's an example use (most sensors are at address 0x77, but some are at 0x76):
iex> {:ok, bmp} = BMP280.start_link(bus_name: "i2c-1", bus_address: 0x77)
{:ok, #PID<0.29929.0>}
iex> BMP280.measure(bmp)
{:ok,
%BMP280.Measurement{
altitude_m: 138.96206905098805,
dew_point_c: 2.629181073094435,
gas_resistance_ohms: 5279.474749704044,
humidity_rh: 34.39681642351278,
pressure_pa: 100818.86273677988,
temperature_c: 18.645856498100876,
timestamp_ms: 885906
}}
Depending on your hardware configuration, you may need to modify the call to
BMP280.start_link/1. See t:BMP280.options/0 for parameters.
All measurements are reported in SI units.
The altitude measurement is computed from the measured barometric pressure. To be accurate, it requires either the current sea level pressure or the current altitude. Here's an example:
iex> BMP280.force_altitude(bmp, 100)
:okSubsequent altitude reports should be more accurate until the weather changes.
Nerves Livebook Firmware contains BMP280 example, which shows you how to work with the BMP280 sensor on the Nerves projects with example code that is runnable from the comfort of your browser.
Please check out this other Elixir library BMP3XX for Bosch BMP388 and BMP390 sensors.
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