Published May 27, 2018 © GPL3+

Stopwatch with Arduino starter kit

Stopwatch with start/pause/lap/reset functions built with Arduino uno, LCD and two switches.

IntermediateShowcase (no instructions)12,264

Things used in this project

Hardware components

Arduino UNO

Adafruit Standard LCD - 16x2 White on Blue

Rotary potentiometer (generic)

SparkFun Pushbutton switch 12mm

Jumper wires (generic)

Resistor 221 ohm

Resistor 10k ohm

Story

Build from the ground up and improve step by step:

1. learn millis() and LCD (project book project 8 and 11)

2. program to enable timming and display

3. install two switches to realize start(button 1) and reset(button 2) function

4. add stop function to button 1

5. change stop function to pause function

6. add lap&display function to button 2 when timing

7. improve the stopwatch by display timming at row 0 col 0, display lap spilts at row 0 col 1 and row 1 col 1

Code

Untitled file

 //function: stopwatch with start/stop(button 1) and reset(button 2)
//start/pause button 1 
//add lap function success!!
//improve lap function scuuess!!
 #include<LiquidCrystal.h>
 LiquidCrystal lcd(12,11,7,6,5,4);

 int ss1 = 0, ss2 = 0;
 int pss1 = 0;
 int ms=0,sec =0, minute=0;
long interval = 98;
unsigned long last=0,dur,pre=0,last2=0,dur2;
 int num_rise=0;
bool reset=0,row=0;

void timeNprint(){
    unsigned long curr = millis();
    if (curr-pre>interval){
    pre=curr;
    ms++;
      if (ms==10) {sec++;ms=0;}
      if (sec==60) {sec=0;minute++;}
    lcd.setCursor(0,0);
      if (minute<10) lcd.print("0");
    lcd.print(minute);
    lcd.print(":");
    if (sec<10) lcd.print("0");
    lcd.print(sec);
    lcd.print(":");
    lcd.print(ms);
    }
}
void printTime(){
  lcd.setCursor(9,row);
  row=!row;
      if (minute<10) lcd.print("0");
    lcd.print(minute);
    lcd.print(":");
    if (sec<10) lcd.print("0");
    lcd.print(sec);
    lcd.print(":");
    lcd.print(ms);
  }
void resetNwelcome(){
  ms=0;minute=0;sec=0;
  lcd.setCursor(0,1);
  lcd.print("XW's Stopwatch");
  lcd.setCursor(0,0);
  lcd.print("Welcome to use");
}

void setup() {
lcd.begin(16,2);
pinMode(2,INPUT);
pinMode(3,INPUT);
}

void loop() {
  num_rise=0;
  resetNwelcome();
  ss1=digitalRead(2);
if (ss1 == HIGH) 
{
  num_rise++;
  last=millis();
  lcd.clear();
  while(1) //stop
  {
    switch(num_rise%2)
    {
      case 0:   //pause
      ss2=digitalRead(3);
      ss1=digitalRead(2);
      dur=millis()-last;
      if (ss2==HIGH) {reset=1;break;}
      else if(ss1==HIGH && dur>300) {
        num_rise++;
        last=millis();}
      break;
      case 1:   
      timeNprint();
      ss1=digitalRead(2);dur=millis()-last;
      if (ss1==HIGH &&dur>300) {
        num_rise++;
        last=millis();
        } 
      break;
      
     }
      ss2=digitalRead(3);
      dur2=millis()-last2;
    if(ss2==1 && dur2>300) 
    {
      last2=millis();
      printTime();
      }
    if(reset==1) 
    {reset=0;lcd.clear();row=0;break;}
   }
}
}