//**********************************************************************
//
//  Version   YY/MM/DD     Comments
//  1.01      18/12/01     Running code
//
//  Adjust two potentiometers to clculate a sum value.
//
//**********************************************************************

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
//   LCD pins:  RS  EN DB4 DB5 DB6 DB7
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

//i/o
const byte firstNumberPot  = A0;
const byte secondNumberPot = A1;

//sram
int firstNumberPotReading;
int firstValue;
int secondNumberPotReading;
int secondValue;

//timing stuff
unsigned long firstValueMillis;
unsigned long secondValueMillis;
unsigned long printMillis;


//**********************************************************************
void setup()
{
  Serial.begin(9600);

  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);

  //         0123456789111111
  //                   012345
  lcd.print("Pot.  Calculator");

  delay(2000);

} //END of setup()

//**********************************************************************
void loop()
{
  //*********************************************
  //adjust the first variable
  firstNumberPotReading = analogRead(firstNumberPot);

  //don't adjust
  if (firstNumberPotReading > 450 && firstNumberPotReading < 550)
  {
    //do nothing
  }

  //slow increment
  else if (firstNumberPotReading > 550 && firstNumberPotReading < 700)
  {
    if (millis() - firstValueMillis >= 500)
    {
      //restart timer
      firstValueMillis = millis();

      firstValue++;
    }
  }

  //slow decrement
  else if (firstNumberPotReading < 400 && firstNumberPotReading > 300)
  {
    if (millis() - firstValueMillis >= 500)
    {
      //restart timer
      firstValueMillis = millis();

      firstValue--;
    }
  }

  //fast increment
  else if (firstNumberPotReading > 700)
  {
    if (millis() - firstValueMillis >= 100)
    {
      //restart timer
      firstValueMillis = millis();

      firstValue++;
    }
  }

  //fast decrement
  else if (firstNumberPotReading < 300)
  {
    if (millis() - firstValueMillis >= 100)
    {
      //restart timer
      firstValueMillis = millis();

      firstValue--;
    }
  }

  //*********************************************
  //adjust the second variable
  secondNumberPotReading = analogRead(secondNumberPot);

  //don't adjust
  if (secondNumberPotReading > 450 && secondNumberPotReading < 550)
  {
    //do nothing
  }

  //slow increment
  else if (secondNumberPotReading > 550 && secondNumberPotReading < 700)
  {
    if (millis() - secondValueMillis >= 500)
    {
      //restart timer
      secondValueMillis = millis();

      secondValue++;
    }
  }

  //slow decrement
  else if (secondNumberPotReading < 400 && secondNumberPotReading > 300)
  {
    if (millis() - secondValueMillis >= 500)
    {
      //restart timer
      secondValueMillis = millis();

      secondValue--;
    }
  }

  //fast increment
  else if (secondNumberPotReading > 700)
  {
    if (millis() - secondValueMillis >= 100)
    {
      //restart timer
      secondValueMillis = millis();

      secondValue++;
    }
  }

  //fast decrement
  else if (secondNumberPotReading < 300)
  {
    if (millis() - secondValueMillis >= 100)
    {
      //restart timer
      secondValueMillis = millis();

      secondValue--;
    }
  }

  //*********************************************
  if (millis() - printMillis >= 500)
  {
    //restart timer
    printMillis = millis();

    Serial.print(firstValue);
    Serial.print(" + ");
    Serial.print(secondValue);
    Serial.print(" = ");
    Serial.println(firstValue + secondValue);

    lcd.setCursor(0, 0); 
    //clear the line
    //                   111111
    //         0123456789012345
    lcd.print("                ");

    lcd.setCursor(0, 0); 
    lcd.print(firstValue);
    lcd.print(" + ");
    lcd.print(secondValue);
    lcd.print(" = ");
    lcd.print(firstValue + secondValue);
  }
} //END of loop()

//***