/*
  Analog input, analog output, serial output
  Reads an analog input pin, maps the result to a range from 0 to 255 and uses
  the result to set the pulse width modulation (PWM) of an output pin.
  Also prints the results to the Serial Monitor.
  The circuit:
  - potentiometer connected to analog pin 0.
    Center pin of the potentiometer goes to the analog pin.
    side pins of the potentiometer go to +5V and ground
  - LED connected from digital pin 9 to ground
  created 29 Dec. 2008
  modified 9 Apr 2012
  by Tom Igoe
  This example code is in the public domain.
  https://www.arduino.cc/en/Tutorial/AnalogInOutSerial
*/

// These constants won't change. They're used to give names to the pins used:
const int analogInPin = A0;  // Analog input pin that the potentiometer is attached to
const int analogOutPin = 9; // Analog output pin that the LED is attached to
int newSensorValue = 0;        // value read from the pot
int newOutputValue = 0;        // value output to the PWM (analog out)

//************************************************************************
// Relays alternately turn on/off when the potentiometer is past midpoint.
//************************************************************************
int newRelayRight = 2;
int newRelayLeft = 3;

int oldRelayRight, oldRelayLeft, oldOutputValue, oldSensorValue;

void setup() {
  // initialize serial communications at 9600 bps:
  Serial.begin(9600);

  //************************************************************************
  // Relays
  //************************************************************************
  pinMode(newRelayRight, OUTPUT);
  pinMode(newRelayLeft, OUTPUT);

  welcome();
}

void loop() {

  // read the analog in value:
  newSensorValue = analogRead(analogInPin);

  // map sersorValue to the range of the analog out:
  newOutputValue = map(newSensorValue, 0, 1023, 0, 255);

  //*******************************************************************************
  // LEFT relay ON if sensor < 480, RIGHT relay ON if sensor > 530, BOTH OFF 480 < relay < 530
  //*******************************************************************************
  if (newSensorValue < 480) {
    digitalWrite(newRelayRight, LOW);
    digitalWrite(newRelayLeft, HIGH);
  } else if (newSensorValue > 530) {
    digitalWrite(newRelayRight, HIGH);
    digitalWrite(newRelayLeft, LOW);
  } else { // deadband
    digitalWrite(newRelayRight, LOW);
    digitalWrite(newRelayLeft, LOW);
  }

  if (newSensorValue) { // the first sensor reading is probably zero... do not show zero

    // this checks the values and only if one of them changes will data be sent to the serial monitor
    if ((oldSensorValue != newSensorValue) || 
        (oldOutputValue != newOutputValue) || 
        (oldRelayLeft != newRelayLeft) || 
        (oldRelayRight != newRelayRight)) {
          
      // change the analog out value:
      analogWrite(analogOutPin, newOutputValue);

      // print the results to the Serial Monitor...
      Serial.print("Analog input = ");
      spacePad(newSensorValue);
      Serial.print(newSensorValue);

      Serial.print("\t PWM output = ");
      spacePad(newOutputValue);
      Serial.print(newOutputValue);

      Serial.print("\t Relay statuss = ");
      Serial.print(digitalRead(newRelayLeft));
      Serial.print(" | ");
      Serial.println(digitalRead(newRelayRight));
    }

    // store old values for checking if any changes on the next loop
    oldSensorValue = newSensorValue;
    oldOutputValue = newOutputValue;
    oldRelayLeft   = newRelayLeft;
    oldRelayRight  = newRelayRight;
  }
}

void spacePad(int value) { // for column formatting of three digits
  if (value < 100)
    Serial.print(" ");
  if (value < 10)
    Serial.print(" ");
}

void welcome() {
  Serial.println("* Adjust Analog In. * Only changes will be displayed. * Relays alternate states at midpoint.");
}