/*********************************************************************
  Project: Stopwatch with LCD Display
  Author: [Your Name]
  Date: [Date]
  Description: This Arduino sketch implements a simple stopwatch using
               an LCD display and two pushbuttons. One button starts
               the stopwatch, and the other button stops it. The elapsed
               time is displayed on the LCD.

  Components:
  - Arduino Uno or similar board
  - LiquidCrystal library
  - 16x2 LCD display
  - 2 pushbuttons

  Connections:
  - LCD:
    - RS (Register Select) pin to Arduino digital pin 7
    - Enable pin to Arduino digital pin 6
    - D4, D5, D6, D7 pins to Arduino digital pins 5, 4, 3, 2 respectively
  - Pushbuttons:
    - Start button connected between Arduino digital pin 8 and ground
      with a pull-up resistor
    - Stop button connected between Arduino digital pin 9 and ground
      with a pull-up resistor
  - Power:
    - Arduino board powered via USB or external power source

  Usage:
  1. Upload this sketch to the Arduino board.
  2. Press the Start button to start the stopwatch. The elapsed time 
     will be displayed on the LCD.
  3. Press the Stop button to pause the stopwatch. The elapsed time 
     will freeze on the LCD until the Start button is pressed again.
  4. Pressing the Start button again will resume the stopwatch from
     the point it was paused.

  Notes:
  - The stopwatch uses the millis() function to measure elapsed time.
  - The LCD displays the elapsed time in seconds.
  - The stopwatch can be reset by restarting the Arduino or by resetting
    the pushbuttons.

  References:
  - LiquidCrystal library: https://www.arduino.cc/en/Reference/LiquidCrystal
  - Arduino millis(): https://www.arduino.cc/reference/en/language/functions/time/millis/
*********************************************************************/

#include <LiquidCrystal.h>
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);
 
void setup(){
lcd.begin(16, 2);
lcd.clear();
 
Serial.begin(9600);
 
pinMode(8, INPUT);
digitalWrite(8, HIGH);
pinMode(9, INPUT);
digitalWrite(9, HIGH);
}
double i = 0;
double a = millis();
double c ;
 
void loop(){
lcd.clear();
lcd.print("press start");
delay(100);
 
if(digitalRead(8) == LOW){
 
lcd.clear();
a = millis();

while(digitalRead(9) == HIGH){
 
c = millis();
i = (c - a) / 1000;
lcd.print(i);
lcd.setCursor(7,0);
lcd.print("Sec's");
lcd.setCursor(0,0);
Serial.println(c);
Serial.println(a);
Serial.println(i);
Serial.println("......");
delay(100);
}
 
if(digitalRead(9) == LOW)
{
while(digitalRead(8) == HIGH)
{
lcd.setCursor(0,0);
lcd.print(i);
lcd.setCursor(11,0);
lcd.print("");
lcd.setCursor(0,0);
delay(100);
}
}
}
}