4 digit 7 segment countdown timer...help!

Projects General Guidance
1

Hello all! im new here and to arduino, so im a little slow in all this stuff.

I got tasked to build a prop bomb for a film, this bombs need to coundown from 59.59 to zero and need to have a restart button and a stop button, but first things first, im stuck with the counting, i have counting from 999.9 (being 999 seconds and 9 ms) to zero, but i cant find how to change that to 59.59 (minutes, seconds)

The second advice i need is how to setup a second button there to make it pause the counting and use the pther button to reset the counting, if its not possible it can be the same button like ''clic'' pause, another ''clic'' reset...

I have and arduino uno and my display is a 5641AS type common cathode this is the code i found on internet and make it work on my hardware

//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

int a = 5;
int b = 7;
int c = 9;
int d = 11;
int e = 12;
int f = 6;
int g = 8;
int p = 10;

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

int startStopReset = 13; 

long n = 999000; //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 = 999000; //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);
}

Thanks in advance for the help!

2 
  clearLEDs();
  pickDigit(1);
  pickNumber((n/x/1000)%10);
  delayMicroseconds(del);

This repeated code displays a single digit of n to a single digit on a selected ("picked") display.

Rather than countdown a single number of seconds, countdown a variable number of seconds and minutes, and display the constituent digits in the same manner.
Hint: you will need to manage the rollover from zero to fifty-nine seconds/minutes in code, either using the modulo operator %, or using a simple "if"

3

I would use two variables: one for the minutes, one for the seconds. Every second decrease seconds. Decrease minutes when seconds goes below 0, and correct seconds to 59. Make sure seconds is a signed integer type, or it won't go negative. Something like this:

if (millis() - lastTick) >= 1000) {
  lastTick += 1000;
  seconds--;
  if (seconds < 0) {
    seconds = 59;
    minutes--;
  }
  if (seconds == 0 && minutes == 0) {
    doBoom();
  }
}