Elixir morse encoder example - step 6

morse_encoder.ex

  defp blink_led(nil, _l) do
    :ok
  end

  defp blink_led(gpio_num, l) do
    gpio = get_gpio()
    GPIO.set_direction(gpio, gpio_num, :output)

    Enum.each(l, fn e ->
      case e do
        ?\s ->
          GPIO.set_level(gpio, gpio_num, 0)
          :timer.sleep(120)

        ?. ->
          GPIO.set_level(gpio, gpio_num, 1)
          :timer.sleep(120)
          GPIO.set_level(gpio, gpio_num, 0)
          :timer.sleep(120)

        ?- ->
          GPIO.set_level(gpio, gpio_num, 1)
          :timer.sleep(120 * 3)
          GPIO.set_level(gpio, gpio_num, 0)
          :timer.sleep(120)
      end
    end)
  end

  defp get_gpio() do
    case Process.whereis(:gpio) do
      nil ->
        gpio = GPIO.open()
        Process.register(gpio, :gpio)
        gpio

      p ->
        p
    end
  end