Photoresistor

ピンを開く

{:ok, cs} = Circuits.GPIO.open("GPIO17", :output)
{:ok, clk} = Circuits.GPIO.open("GPIO18", :output)
{:ok, dio} = Circuits.GPIO.open("GPIO27", :output)

モジュール定義

defmodule ADC do
  import Bitwise

  def get_result(dio, clk, cs, channel \\ 0) do
    sel = if channel > 1, do: 1, else: 0
    odd = channel &&& 1

    Circuits.GPIO.write(cs, 0)

    start_adc(dio, clk)
    single_end_mode(dio, clk)
    set_odd(dio, clk, odd)
    set_sel(dio, clk, sel)

    Circuits.GPIO.set_direction(dio, :input)

    dat1 =
      0..7
      |> Enum.reduce(0, fn _i, acc ->
        Circuits.GPIO.write(clk, 1)
        :timer.sleep(2)
        Circuits.GPIO.write(clk, 0)
        :timer.sleep(2)

        Circuits.GPIO.set_direction(dio, :input)

        bit = Circuits.GPIO.read(dio)
        acc = acc <<< 1 ||| bit
        acc
      end)

    dat2 =
      0..7
      |> Enum.reduce(0, fn i, acc ->
        bit = Circuits.GPIO.read(dio)
        acc = acc ||| bit <<< i
        Circuits.GPIO.write(clk, 1)
        :timer.sleep(2)
        Circuits.GPIO.write(clk, 0)
        :timer.sleep(2)

        acc
      end)

    Circuits.GPIO.write(cs, 1)
    Circuits.GPIO.set_direction(dio, :output)

    if dat1 == dat2, do: dat1, else: 0
  end

  defp start_adc(dio, clk) do
    Circuits.GPIO.write(clk, 0)
    Circuits.GPIO.write(dio, 1)
    :timer.sleep(2)
    Circuits.GPIO.write(clk, 1)
    :timer.sleep(2)
  end

  defp single_end_mode(dio, clk) do
    Circuits.GPIO.write(clk, 0)
    Circuits.GPIO.write(dio, 1)
    :timer.sleep(2)
    Circuits.GPIO.write(clk, 1)
    :timer.sleep(2)
  end

  defp set_odd(dio, clk, odd) do
    Circuits.GPIO.write(clk, 0)
    Circuits.GPIO.write(dio, odd)
    :timer.sleep(2)
    Circuits.GPIO.write(clk, 1)
    :timer.sleep(2)
  end

  defp set_sel(dio, clk, sel) do
    Circuits.GPIO.write(clk, 0)
    Circuits.GPIO.write(dio, sel)
    :timer.sleep(2)
    Circuits.GPIO.write(clk, 1)
    :timer.sleep(2)
    Circuits.GPIO.write(clk, 0)
    :timer.sleep(2)
  end
end

アナログ値を取得する

analog_val = ADC.get_result(dio, clk, cs)

LEDの点灯

duty = round(analog_val * 1_000_000 / 255)
duty / 10000

Pigpiox.Pwm.hardware_pwm(12, 2000, duty)

フォトレジスタとLEDを連動させる

1..300
|> Enum.map(fn _i ->
  analog_val = ADC.get_result(dio, clk, cs)
  duty = round(analog_val * 1_000_000 / 255)
  IO.inspect(duty / 10000)
  Pigpiox.Pwm.hardware_pwm(12, 2000, duty)
end)

ピンを閉じる

Circuits.GPIO.close(cs)
Circuits.GPIO.close(clk)
Circuits.GPIO.close(dio)