Arduino Stopwatch




About: If it moves and it isn't supposed to move, Duct Tape it. If it doesn't move and its supposed to move, WD40 it. Hack with Sugru. Conor is a participant in the Amazon Services LLC Associates Program, an affi...

This Instructable will show you how to make a stop watch out of an Arduino.

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Step 1: What You Will Need

Please buy through these Amazon links as it helps me to keep making these Instructables (A small cut of Amazon's profit from the sale is given to me - It doesn't cost you anything!)

You Will Need:

- 1x Arduino Uno:

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- 1x LCD Keypad Shield:

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- 1x USB A - B Connector Cable:

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What I Recommend:

- Amazon Prime so you can get all your items the next day:

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- You could attach some of these magnets to attach the stopwatch onto nearly anything metal:

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- Arduino For Dummies (very helpful when learning code):

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- Arduino Projects For Dummies:

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Step 2: Slot the LCD Display Onto the Arduino

This step is very simple just slot the LCD display onto the Arduino.

Step 3: Connect and Install the Program

Just connect your Arduino to The Computer and install the program.

Update - Please use the Modified Stopwatch Program.

Step 4: Run Your Stopwatch

Now just run your stopwatch.

5 People Made This Project!


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39 Discussions

Conor Mrandim19

Reply 7 months ago

Sorry about the late replay.
Of course you can as long as you credit this page and me!


4 years ago on Introduction

Very cool idea and a great starting point, thanks!!!

I did a bit of rewrite to make it more accurate and display the time as it progresses plus other tweaks :


Standalone Arduino StopWatch

By Conor M - 11/05/15

Modified by Elac - 12/05/15


// call the necessary libraries
#include <SPI.h>
#include <LiquidCrystal.h>
// these are the pins used on the shield for this sketch
LiquidCrystal lcd(8, 13, 9, 4, 5, 6, 7);
// variables used on more than 1 function need to be declared here
unsigned long start, finished, elapsed;
boolean r = false;
// Variables for button debounce time
long lastButtonPressTime = 0; // the last time the button was pressed
long debounceDelay = 50; // the debounce time; keep this as low as possible

void setup()
lcd.begin(16, 2); // inicialize the lcd (16 chars, 2 lines)

// a little introduction :)
lcd.setCursor(4, 0); // set the cursor to first character on line 1 - NOT needed (it sets automatically on lcd.begin()
lcd.setCursor(3, 1); // set the cursor to 4th character on line 2
delay(2000); // wait 2 seconds
lcd.clear(); // clear the display
lcd.print("Press select for");
lcd.setCursor(2, 1); // set the cursor to 3rd character on line 2
lcd.print("Start & Stop");

void loop()

void CheckStartStop()
int x = analogRead (0); // assign 'x' to the Arduino's AnalogueInputs (Shield's buttons)
if (x < 800 && x > 600 ) // if the button is SELECT
if ((millis() - lastButtonPressTime) > debounceDelay)

if (r == false)
lcd.setCursor(2, 0); // needed
lcd.print("Elapsed Time");
start = millis(); // saves start time to calculate the elapsed time
else if (r == true)
lcd.setCursor(2, 0); // needed
lcd.print(" Final Time ");
r = !r;
lastButtonPressTime = millis();

void DisplayResult()
if (r == true)
finished = millis(); // saves stop time to calculate the elapsed time
// declare variables
float h, m, s, ms;
unsigned long over;

// MATH time!!!
elapsed = finished - start;

h = int(elapsed / 3600000);
over = elapsed % 3600000;
m = int(over / 60000);
over = over % 60000;
s = int(over / 1000);
ms = over % 1000;
// display the results
lcd.setCursor(0, 1);
lcd.print(h, 0); // display variable 'h' - the 0 after it is the number of algorithms after a comma (ex: lcd.print(h, 2); would print 0,00
lcd.print("h "); // and the letter 'h' after it
lcd.print(m, 0);
lcd.print("m ");
lcd.print(s, 0);
lcd.print("s ");
if (h < 10)
lcd.print(ms, 0);
lcd.print("ms ");

2 replies

Reply 2 years ago


I only want to count time while the button or another input is present , how would I go about this?


2 years ago

thank you very much

WhatsApp Image 2017-05-20 at 11.10.05 PM.jpeg

2 years ago

I'm struggling to get external buttons to work - I want to add a start and stop but keep getting stuck! Anybody done this with the modified code? :)


2 years ago

Welcome to join the group :)


3 years ago

how to install the program I don't see anything on my computer after connecting the arduino to it. do we need some software like matlab or something?

1 reply
Conor Mjagdeep010

Reply 3 years ago

Make sure you have downloaded the arduino software from


3 years ago

I want a coding I want to connect ir sensor to micro servo so that if something pass from front of ir sensor servo rotates at a 90 degree angle and returns to its initial position. I have a ARDUINO UNO for the purpose.... Can anybody do coding for this..PLZ PLZ PLZ THANK YOU... HOPE U REPLY...

please reply here --

2 replies
Conor Mamans149

Reply 3 years ago

Check out one of my other instructables, how to make an arduino web server, it uses a servo, hope it helps

R Jordan Kreindler

3 years ago

Outstanding. I am using it and am happy to say it works without problem.

musi mumu

3 years ago

can somebody give me a version for measuring and displaying seconds,miliseconds and microseconds all on 3 digits each . If yes thanks in advance and contact me at


3 years ago

on the line elapsed = finished - start I am getting an error 'start' was not declared in this scope.

Any ideas?