Build a Reliable Arduino Countdown Timer with SparkFun 7‑Segment Display

Apps and online services

Arduino IDE

About this project

This project was a project designed specifically because I did not have a timer on hand. To use this project you simply just upload the code to your arduino (any type will work) you will just need upload the code to the arduino and the countdown will automatically start. Should you want to change the total time you will need to change this part of code. REMEMBER!!! 1000= 1 sec. so 60000 = sec 60 or the equation (SECx1000) will give you your total number to insert into the place of the 60000. Finally when you press the reset button the counter automatically restarts.

long n = 60000; //start time -> CAN CHANGE TO WHATEVER TIME YOU WANT

Code

• The code

The codeArduino

//7 segement pin number - 7 segement light - arduino pin number

//pin 11 - A = 12
//pin 7 - B = 10
//pin 4 - C = 8
//pin 2 - D = 7
//pin 1 - E = 6
//pin 10 - F = 11
//pin 5 - G = 9

//pin 3 is decimal

/*
12 11  10  9 8 7
|   |   |  | | | 
    A
   ---
F |   | B
  | G |
   ---
E |   | C
  |   |
   ---  . dec
    D
| | | | | |
1 2 3 4 5 6
*/

//pin 12 - first digit = 1
//pin 9 - second digit = 2 
//pin 8 - third digit = 3
//pin 6 fourth digit = 4

const int a = 12;
const int b = 10;
const int c = 8;
const int d = 7;
const int e = 6;
const int f = 11;
const int g = 9;
int p = 0;

int startStopReset = 13; 

const int d1 =1;
const int d2 =2;
const int d3 =3;
const int d4 =4;

long n = 60000; //start time -> CAN CHANGE TO WHATEVER TIME YOU WANT
int x = 100; 
int del = 55; //delay value
 
void setup()
{
  pinMode(d1, OUTPUT);
  pinMode(d2, OUTPUT);
  pinMode(d3, OUTPUT);
  pinMode(d4, OUTPUT);
  pinMode(a, OUTPUT);
  pinMode(b, OUTPUT);
  pinMode(c, OUTPUT);
  pinMode(d, OUTPUT);
  pinMode(e, OUTPUT);
  pinMode(f, OUTPUT);
  pinMode(g, OUTPUT);
  pinMode(p, OUTPUT);
  pinMode(startStopReset, INPUT); 
  digitalWrite(startStopReset, HIGH); 
}
 
void loop()
{
  digitalWrite (p, HIGH);

  clearLEDs();
  pickDigit(1);
  pickNumber((n/x/1000)%10);
  delayMicroseconds(del);
 
  clearLEDs();
  pickDigit(2);
  pickNumber((n/x/100)%10);
  delayMicroseconds(del);
 
  clearLEDs();
  pickDigit(3);
  dispDec(3);
  pickNumber((n/x/10)%10);
  delayMicroseconds(del);
 
  clearLEDs();
  pickDigit(4);
  pickNumber(n/x%10);
  delayMicroseconds(del);
 
  n--; //'n++' for stopwatch
 
  if (digitalRead(13) == LOW)
  {
    n = 60000; //re-start time -> CHANGE TO WHATEVER TIME YOU ORIGONALLY SET (start time)
  }
}
 
void pickDigit(int x) //changes digit
{
  digitalWrite(d1, HIGH);
  digitalWrite(d2, HIGH);
  digitalWrite(d3, HIGH);
  digitalWrite(d4, HIGH);
 
  switch(x)
  {
  case 1: 
    digitalWrite(d1, LOW); 
    break;
  case 2: 
    digitalWrite(d2, LOW); 
    break;
  case 3: 
    digitalWrite(d3, LOW);
    digitalWrite(p, HIGH); //new 
    break;
  default: 
    digitalWrite(d4, LOW); 
    break;
  }
}
 
void pickNumber(int x) //changes value of number
{
  switch(x)
  {
  default: 
    zero(); 
    break;
  case 1: 
    one(); 
    break;
  case 2: 
    two(); 
    break;
  case 3: 
    three(); 
    break;
  case 4: 
    four(); 
    break;
  case 5: 
    five(); 
    break;
  case 6: 
    six(); 
    break;
  case 7: 
    seven(); 
    break;
  case 8: 
    eight(); 
    break;
  case 9: 
    nine(); 
    break;
  }
}
 
void dispDec(int x)
{
  digitalWrite(p, LOW);
}
 
void clearLEDs()
{
  digitalWrite(a, LOW);
  digitalWrite(b, LOW);
  digitalWrite(c, LOW);
  digitalWrite(d, LOW);
  digitalWrite(e, LOW);
  digitalWrite(f, LOW);
  digitalWrite(g, LOW);
  digitalWrite(p, LOW);
}
 
void zero()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(g, LOW);
}
 
void one()
{
  digitalWrite(a, LOW);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, LOW);
  digitalWrite(e, LOW);
  digitalWrite(f, LOW);
  digitalWrite(g, LOW);
}
 
void two()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, LOW);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, LOW);
  digitalWrite(g, HIGH);
}
 
void three()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, LOW);
  digitalWrite(f, LOW);
  digitalWrite(g, HIGH);
}
 
void four()
{
  digitalWrite(a, LOW);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, LOW);
  digitalWrite(e, LOW);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
}
 
void five()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, LOW);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, LOW);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
}
 
void six()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, LOW);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
}
 
void seven()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, LOW);
  digitalWrite(e, LOW);
  digitalWrite(f, LOW);
  digitalWrite(g, LOW);
}
 
void eight()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, HIGH);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
}
 
void nine()
{
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  digitalWrite(c, HIGH);
  digitalWrite(d, HIGH);
  digitalWrite(e, LOW);
  digitalWrite(f, HIGH);
  digitalWrite(g, HIGH);
}

Schematics