-------------------------------------------------------------------------------
-- |
-- Module      :  System.Hardware.Arduino.SamplePrograms.Analog
-- Copyright   :  (c) Levent Erkok
-- License     :  BSD3
-- Maintainer  :  erkokl@gmail.com
-- Stability   :  experimental
--
-- Reads the value of an analog input, controlled by a 10K potentiometer.
-------------------------------------------------------------------------------

module System.Hardware.Arduino.SamplePrograms.Analog where

import Control.Monad       (when)
import Control.Monad.Trans (liftIO)

import System.Hardware.Arduino

-- | Read the value of an analog input line. We will print the value
-- on the screen, and also blink a led on the Arduino based on the
-- value. The smaller the value, the faster the blink.
--
-- The circuit simply has a 10K potentiometer between 5V and GND, with
-- the wiper line connected to analog input 3. We also have a led between
-- pin 13 and GND.
--
--  <<http://github.com/LeventErkok/hArduino/raw/master/System/Hardware/Arduino/SamplePrograms/Schematics/Analog.png>>
analogVal :: IO ()
analogVal :: IO ()
analogVal = Bool -> FilePath -> Arduino () -> IO ()
withArduino Bool
False FilePath
"/dev/cu.usbmodemFD131" (Arduino () -> IO ()) -> Arduino () -> IO ()
forall a b. (a -> b) -> a -> b
$ do
               Pin -> PinMode -> Arduino ()
setPinMode Pin
led PinMode
OUTPUT
               Pin -> PinMode -> Arduino ()
setPinMode Pin
pot PinMode
ANALOG
               cur <- Pin -> Arduino Int
analogRead Pin
pot
               liftIO $ print cur
               go cur
  where led :: Pin
led = Word8 -> Pin
digital Word8
13
        pot :: Pin
pot = Word8 -> Pin
analog Word8
3
        go :: Int -> Arduino b
go Int
cur = do Pin -> Bool -> Arduino ()
digitalWrite Pin
led Bool
True
                    Int -> Arduino ()
delay Int
cur
                    Pin -> Bool -> Arduino ()
digitalWrite Pin
led Bool
False
                    Int -> Arduino ()
delay Int
cur
                    new <- Pin -> Arduino Int
analogRead Pin
pot
                    when (cur /= new) $ liftIO $ print new
                    go new