Stopwatch Using Push Button By Arduino

Introduction

LCD Display:

LCD display is a flat panel display.
It does not emit light directly.
It will display arbitrary images or fixed images with low information.

Uses:

Computer Monitor
Televisions
Instrument Panels

Figure 1: LCD Display

Potentiometer:

It can have the three terminals.
It can have sliding or rotating contact that forms a adjustable voltage divider.
It act as a variable resistor (or) rheostat.

Figure 2: potentiometer

Push Button:

The push-button connects the two points.
The first pin in the push button are connected to 5Vc.
The second pin in the push button is connected to gnd.

Figure3: Push Button

Parts Of List:

Arduino Uno
LCD Display
Potentiometer
Push Button
Bread Board
Hookup Wire
USB cable

Connection:

Step 1: Fix the LCD display in the breadboard and connect it to the Arduino UNO board as per the following figure 4.

Figure 4: LCD Connection.

Step 2: Fix the push button on the breadboard and connect to the Arduino UNO board as per the following figure 5.

Figure5: Pushbutton Connection.

Step 3: Connect the potentiometer to the LCD display and breadboard. Potentiometer center leads to the LCD display 3pin.

Programming:

#include < LiquidCrystal.h >
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
int ledPin = 13;
int buttonPin = 2;
int value = LOW;
int buttonState;
int lastButtonState;
int blinking; // condition for blinking - timer is timing
int frameRate = 100; // the frame rate (frames per second) at which the stopwatch runs - Change to suit
long interval = (1000 / frameRate); // blink interval
long previousMillis = 0; // variable to store last time LED was updated
long startTime; // start time for stop watch
long elapsedTime; // elapsed time for stop watch
int fractional; // variable used to store fractional part of Frames
int fractionalSecs; // variable used to store fractional part of Seconds
int fractionalMins; // variable used to store fractional part of Minutes
int elapsedFrames; // elapsed frames for stop watch
int elapsedSeconds; // elapsed seconds for stop watch
int elapsedMinutes; // elapsed Minutes for stop watch
char buf[10]; // string buffer for itoa function
void setup()
{
lcd.begin(16, 2); // intialise the LCD.
pinMode(ledPin, OUTPUT); // sets the digital pin as output
pinMode(buttonPin, INPUT); // not really necessary, pins default to INPUT anyway
digitalWrite(buttonPin, HIGH); // turn on pullup resistors. Wire button so that press shorts pin to ground.
}
void loop()
{
digitalWrite(ledPin, LOW); // Initiate LED and Step Pin States
buttonState = digitalRead(buttonPin); // Check for button press, read the button state and store
if (buttonState == LOW && lastButtonState == HIGH && blinking == false)
{
startTime = millis(); // store the start time
blinking = true; // turn on blinking while timing
delay(10); // short delay to debounce switch
lastButtonState = buttonState; // store buttonState in lastButtonState, to compare next time
} else if (buttonState == LOW && lastButtonState == HIGH && blinking == true)
{
blinking = false; // turn off blinking, all done timing
lastButtonState = buttonState; // store buttonState in lastButtonState, to compare next time
// Routine to report elapsed time
elapsedTime = millis() - startTime; // store elapsed time
elapsedMinutes = (elapsedTime / 60000 L);
elapsedSeconds = (elapsedTime / 1000 L); // divide by 1000 to convert to seconds - then cast to an int to print
elapsedFrames = (elapsedTime / interval); // divide by 100 to convert to 1/100 of a second - then cast to an int to print
fractional = (int)(elapsedFrames % frameRate); // use modulo operator to get fractional part of 100 Seconds
fractionalSecs = (int)(elapsedSeconds % 60 L); // use modulo operator to get fractional part of 60 Seconds
fractionalMins = (int)(elapsedMinutes % 60 L); // use modulo operator to get fractional part of 60 Minutes
lcd.clear(); // clear the LDC
if (fractionalMins < 10)
{
lcd.print("0"); // add a zero
}
lcd.print(itoa(fractionalMins, buf, 10)); //convert the int to a string and print a fractional part of 60 Minutes to the LCD
lcd.print(":");
if (fractionalSecs < 10)
{
lcd.print("0"); // add a zero
}
lcd.print(itoa(fractionalSecs, buf, 10)); // convert the int to a string and print a fractional part of 60 Seconds to the LCD
lcd.print(":"); //print a colan.
if (fractional < 10)
{
lcd.print("0"); // add a zero
}
lcd.print(itoa(fractional, buf, 10)); // convert the int to a string and print a fractional part of 25 Frames to the LCD
} else
{
lastButtonState = buttonState; // store buttonState in lastButtonState, to compare next time
}
if ((millis() - previousMillis > interval))
{
if (blinking == true) {
previousMillis = millis(); // remember the last time we blinked the LED
digitalWrite(ledPin, HIGH); // Pulse the LED for Visual Feedback
elapsedTime = millis() - startTime; // store elapsed time
elapsedMinutes = (elapsedTime / 60000 L); // divide by 60000 to convert to minutes - then cast to an int to print
elapsedSeconds = (elapsedTime / 1000 L); // divide by 1000 to convert to seconds - then cast to an int to print
elapsedFrames = (elapsedTime / interval); // divide by 40 to convert to 1/25 of a second - then cast to an int to print
fractional = (int)(elapsedFrames % frameRate); // use modulo operator to get fractional part of 25 Frames
fractionalSecs = (int)(elapsedSeconds % 60 L); // use modulo operator to get fractional part of 60 Seconds
fractionalMins = (int)(elapsedMinutes % 60 L); // use modulo operator to get fractional part of 60 Minutes
lcd.clear(); // clear the LDC
if (fractionalMins < 10)
{
lcd.print("0"); // add a zero
}
lcd.print(itoa(fractionalMins, buf, 10)); // convert the int to a string and print a fractional part of 60 Minutes to the LCD
lcd.print(":"); //print a colan.
if (fractionalSecs < 10)
{
lcd.print("0"); // add a zero
}
lcd.print(itoa(fractionalSecs, buf, 10)); // convert the int to a string and print a fractional part of 60 Seconds to the LCD
lcd.print(":"); //print a colan.
if (fractional < 10)
{
lcd.print("0"); // add a zero
}
lcd.print(itoa((fractional), buf, 10)); // convert the int to a string and print a fractional part of 25 Frames to the LCD
} else
{
digitalWrite(ledPin, LOW); // turn off LED when not blinking
}
}
}