visciang / nerves_dht

Elixir library to read the DHT sensors on Raspberry Pi boards

Nerves DHT

Elixir library to read the DHT series of humidity and temperature sensors on a Raspberry Pi. The library is supposed to be included in a nerves project.

If you want to build your project directly on a Raspberry (not in a crosscompiling nerves project) just export MIX_TARGET environment variable to you mix build. Valid values for MIX_TARGET are rpi, rp0, rp2, rp3, rp4.

• Supported sensors: DHT11, DHT22, AM2302
• Supported boards: Raspberry 0, 1, 2, 3, 4

Note: the library has no external dependencies and use a C executable to read the sensors data.

Installation

The package can be installed by adding nerves_dht to your list of dependencies in mix.exs:

def deps do
  [
    {:nerves_dht, git: "https://github.com/visciang/nerves_dht.git", tag: "xxx"}
  ]
end

Usage

iex> NervesDHT.read(:am2302, 17)
{:ok, 55.1, 24.719}

iex> NervesDHT.stream(:am2302, 17) |> Enum.take(2)
[{:ok, 55.1, 24.719}, {:ok, 55.12, 24.9}]

If you plan to read concurrently from the sensor, add NervesDHT to your application supervisor tree:

children = [
  {NervesDHT, [name: :my_sensor, sensor: :am2302, pin: 17]},
  ...
]
Supervisor.start_link(children, strategy: :one_for_one)

and read with:

NervesDHT.device_read(:my_sensor)
NervesDHT.device_stream(:my_sensor)

Test

$ export CI=true    # to build on a non RPI-nerves host
$ mix compile --warnings-as-errors
$ mix coveralls