/******************************************************************************
Filename: StopWatch.ino
Developer(s): Nelson Guevara- Popayán Colombia
              Corporación Universitaria Autónoma del Cauca
 
Language: C
Abstract: This file provides the code for a StopWatch with 3 buttons: Start, Stop and Reset.
************************************************************************************/

/***********************************************************************************
USER INCLUDES
***********************************************************************************/
#include <LiquidCrystal_I2C.h>

/***********************************************************************************
CONSTANT DEFINITIONS
***********************************************************************************/
#define START_BUTTON  26
#define STOP_BUTTON   27
#define RESET_BUTTON  12

/***********************************************************************************
GLOBAL DECLARATION
***********************************************************************************/
unsigned long startTime     = 0;
unsigned long elapsedTime   = 0;
unsigned long pausedTime    = 0;  
unsigned long centiseconds  = 0;
unsigned long totalSeconds  = 0;
unsigned long milliseconds  = 0;
unsigned long seconds       = 0;
unsigned long minutes       = 0;
bool isRunning              = false; 
bool Stop_flag              = false;

/* LCD */
/* Create an LCD object */    
LiquidCrystal_I2C lcd(0x27, 16, 2);

/* TIMER */
/* Create an TIMER object */
hw_timer_t *timer = NULL;

/***********************************************************************************
GLOBAL FUNCTION DECLARATION 
***********************************************************************************/
void IRAM_ATTR Start_Button_ISR();
void IRAM_ATTR Stop_Button_ISR();
void IRAM_ATTR Reset_Button_ISR();
void IRAM_ATTR Timer_ISR();
void startStopwatch();
void stopStopwatch();
void resetStopwatch();


/*******************************************************************************
  Function that sets up external interrupt
*******************************************************************************/
void IRAM_ATTR Start_Button_ISR()
{
  if(!isRunning)
  {
    timerAlarmEnable(timer); 
    startStopwatch();
  }
}

/**********************************************************************************************
 Function that sets up external interrupt
**********************************************************************************************/
void IRAM_ATTR Stop_Button_ISR()
{
  if(isRunning)
  {
    stopStopwatch();
  }
}

/**********************************************************************************************
 Function that sets up external interrupt
**********************************************************************************************/
void IRAM_ATTR Reset_Button_ISR()
{
  resetStopwatch();
}

/**********************************************************************************************
 Function that sets up internal interrupt
**********************************************************************************************/
void IRAM_ATTR Timer_ISR() 
{

  if(!Stop_flag)
  {
    isRunning = true;
  }   
}

/*******************************************************************************
  startStopwatch function
*******************************************************************************/
void startStopwatch() 
{
  startTime = millis();
}

/*******************************************************************************
  stopStopwatch function
*******************************************************************************/
void stopStopwatch() 
{
  pausedTime += millis() - startTime;
  isRunning = false;
  Stop_flag = true;
}

/*******************************************************************************
  resetStopwatch function
*******************************************************************************/
void resetStopwatch() 
{
  startTime = 0;
  pausedTime = 0;
  elapsedTime = 0;
  centiseconds = 0;
  totalSeconds = 0;
  milliseconds = 0;
  seconds = 0;
  minutes = 0;
  isRunning = true;
  Stop_flag = true;
  startStopwatch();
}

/*********************************************************************************
Function in arduino structure to configure initial parameters of
microcontroller and peripherals.
*********************************************************************************/
void setup() {
  Serial.begin(115200);
  pinMode(START_BUTTON, INPUT_PULLUP); 
  pinMode(STOP_BUTTON, INPUT_PULLUP); 
  pinMode(RESET_BUTTON, INPUT_PULLUP); 

  attachInterrupt(START_BUTTON, Start_Button_ISR, RISING);
  attachInterrupt(STOP_BUTTON, Stop_Button_ISR, RISING);
  attachInterrupt(RESET_BUTTON, Reset_Button_ISR, RISING);

  lcd.init(); 
  lcd.backlight(); 
  lcd.setCursor(3, 0);
  lcd.print("STOPWATCH");
  delay(2e3);

  /* Timer configuration */
  timer = timerBegin(0, 80, true);                  
  timerAttachInterrupt(timer, &Timer_ISR, true);    
  timerAlarmWrite(timer, 1e3, true);                

}

/*******************************************************************************
  Main program loop
*******************************************************************************/
void loop() {

  while (isRunning) 
  {
    elapsedTime = millis() - startTime + pausedTime;
    centiseconds = (elapsedTime / 10) % 100;
    totalSeconds = elapsedTime / 1000;
    milliseconds = elapsedTime % 1000;
    seconds = totalSeconds % 60;
    minutes = totalSeconds / 60;

    lcd.setCursor(3, 1);
    lcd.print(String(minutes) + ":" + String(seconds) + ":" + String(centiseconds)+ ":" + String(milliseconds));
  }
  isRunning = false;
}