Blink an external LED with elixir_ale

README.md

Blinky

blinky_ale.ex

defmodule BlinkyAle do
  require Logger

  def start do
    {ok,pid} = Gpio.start_link(4,:output)
    blink_forever(pid)
  end
  
  def blink_forever(pid) do
    Logger.debug "Turning ON"
    Gpio.write(pid,1)
    :timer.sleep 1000
    Logger.debug "turning OFF"
    Gpio.write(pid,0)
    :timer.sleep 1000
    blink_forever(pid)
  end

end

blinky_prox.ex

defmodule BlinkyProx do
  require Logger

  #register       address
  @cmd            0x80
  @prox_result_h  0x87
  @prox_result_l  0x88

  def start do
    {:ok,led_pid} = Gpio.start_link(4,:output)
    #blink_forever(led_pid)

    {:ok,prox_pid} = I2c.start_link("i2c-1", 0x13)
    IO.inspect prox_pid 

    # what is the current value of the command register?
    I2c.write_read(prox_pid,<<@cmd>> ,1) |> Base.encode16 |> IO.inspect

    # turn on proximity sensing by setting bits 0 and 1
    I2c.write(prox_pid, <<@cmd, 0x03>> )

    # check the command register
    I2c.write_read(prox_pid,<<@cmd>> ,1) |> Base.encode16 |> IO.inspect

    # use this to loop and print out proximity values
    # measure(prox_pid)
    
    prox_led(prox_pid,led_pid)
  end

  # turn the led on and off depending on proximity
  def prox_led(prox_pid,led_pid) do

    # binary pattern matching to get the two bytes as an int
    << val :: 16 >> = I2c.write_read(prox_pid,<<@prox_result_h>> ,2) 
    IO.inspect val 
 
    # value determined by running measure/1 and observing the output
    if val > 2100 do
      Logger.debug "ON"  
      Gpio.write(led_pid,1)
    else
      Logger.debug "OFF"
      Gpio.write(led_pid,0)
    end

    :timer.sleep 513
    prox_led(prox_pid,led_pid)
  end

  def measure(prox_pid) do
    # read the 2 bytes of proximity data and loop
    val = I2c.write_read(prox_pid,<<@prox_result_h>> ,2) 
    # display the value in different ways
    val |>  IO.inspect(binaries: :as_binaries)
    val |> Base.encode16 |> IO.inspect
    << my_int :: 16 >> = val
    IO.inspect my_int
    IO.puts ""
    # by default the VCNL4010 reads data about twice a second
    :timer.sleep 513 
    measure(prox_pid)  
  end

end

mix.exs

defmodule Blinky.Mixfile do

end