Ledx

Ledx is a simple library for interfacing with LEDs on embedded platforms.

Installation

1. Add ledx to your list of dependencies in mix.exs:

    def deps do
      [{:ledx, "~> 0.0.1"}]
    end
   

2. Ensure ledx is started before your application:

    def application do
      [applications: [:ledx]]
    end
   

Ledx depends on elixir-ale for interfacing with GPIO. Follow the instructions on getting-started if you are cross-compiling.

Usage

Configure your LEDs

You can configure your LEDs easily in your config.exs file.

config :ledx, leds:
  [{:led1, :gpio, %{pin: 18}},
   {:led2, :gpio, %{pin: 17}}]

This will make :led1 and :led2 be available when your app is started.

Start a LED after application start

You can also start a LED from your code. Just pass the led name, the led type, and the led configuration.

{:ok, _pid} = Ledx.start_led(:my_led, :gpio, %{pin: 18})

Currently only :gpio is supported, see advanced if you want to implement your own types.

Turning on/off a led

Given our previously started led, we could turn it on doing:

Ledx.turn_on(:my_led)
# the led is on!

Then turn it off calling:

Ledx.turn_off(:my_led)
# the led is off

We could also toggle it:

Ledx.toggle(:my_led)
# the led is on
Ledx.toggle(:my_led)
# the led is off

Pulses

Sometimes you want to turn on a LED just for a certain time:

Ledx.turn_on(:my_led, 100)
# the led is on for 100 ms
# then off

Or turn it off for a certain time:

Ledx.turn_off(:my_led, 100)
# the led is off for 100 ms
# then on

Or toggle it for a certain time:

Ledx.toggle(:my_led, 100)
# the led toggles for 100 ms
# then toggles again

Blink

It's also really easy to repeatedly blink a led:

Ledx.blink(:my_led, 100, 50)
# the led is on for 100 ms
# then off for 50 ms
# then on for 100 ms
# ...

Examples

You can find examples in the examples directory.

Advanced

Implementing you own drivers

You just need to implement the Ledx.Driver behaviour:

defmodule MyDriver do
  @behaviour Ledx.Driver

  def init(config) do
    # your init code here
    config
  end

  def on(config) do
    # your code that turns the led on
    config
  end

  def off(config) do
    # your code that turns the led off
    config
  end
end

You can check the implementation of Ledx.Drivers.Gpio to see an example.

Starting LEDs using your own drivers

To start a led, you need to call start_led/3 passing a name for the led, a driver module, and the configuration needed for the driver.

{:ok, _pid} = Ledx.start_led(:my_led, MyDriver, %{pin: 18})

You can also start LEDs with your own drivers, using the config.exs file:

config :ledx, leds:
  [{:led1, MyDriver, %{path: "/dev/led/led1"}},
   {:led2, MyDriver, %{path: "/dev/led/led2"}}]