# BMP280

[![Hex version]( "Hex version")](

Read temperature and pressure from Bosch
sensors in Elixir.

## Usage

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)
   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)

Subsequent altitude reports should be more accurate until the weather changes.

## Nerves Livebook Firmware

[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.

## Support for other Bosch barometric sensors

Other Bosch sensors tend to look similar, but they have enough differences that
they do not work yet. If you're using one of them, please help me by either
verifying that they work or adding support for them.