how when the push button is pressed the timer starts?

Projects Programming
1

when the push button is pressed the timer starts? and timers that have been set to work. when the timer off the system will return to the initial conditions.

#include <LiquidCrystal.h>
int hours = 0 ; // start hours
int minutes = 2 ; //start min
int seconds = 0; //start seconds
//LiquidCrystal lcd(12, 11, 5, 4, 3, 2); //<--removed- Different LCD manufacture
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);//Pin Code for Arduino SainSmart LCD 1602 KeyPad

void setup() {
}

void loop() {
lcd.begin(16, 2);
lcd.print("Count Down Timer ");

// lcd.scrollDisplayLeft();
// wait a bit:
delay(150);

while (hours > 0 || minutes > 0 || seconds >= 0) {

lcd.setCursor(4, 2);
(hours < 10) ? lcd.print("0") : NULL;
lcd.print(hours);
lcd.print(":");
(minutes < 10) ? lcd.print("0") : NULL;
lcd.print(minutes);
lcd.print(":");
(seconds < 10) ? lcd.print("0") : NULL;
lcd.print(seconds);
lcd.display();
stepDown();
delay(1000);
}
}

void stepDown()
{
if (seconds > 0) {
seconds -= 1;
} else {
if (minutes > 0) {
seconds = 59;
minutes -= 1;
} else {
if (hours > 0) {
seconds = 59;
minutes = 59;
hours -= 1;
} else {
trigger();
}
}
}
}

void trigger() {
lcd.clear(); // clears the screen and buffer
lcd.setCursor(5, 1); // set timer position on lcd for end.

lcd.println("OFF");
delay(1000);

lcd.display();
}

2

First, open this link: How to use this forum - please read., scroll down to the item 7 and follow the steps.

(Put your code insided CODE brackets)

3

syahrisal:
when the push button is pressed the timer starts? and timers that have been set to work. when the timer off the system will return to the initial conditions.

That is not how to work it. There is a timer that counts milliseconds as an unsigned long since the board powered up. When you want to count time from some point, save the value of the counter

unsigned long markStart, timeElapsed;

.................... // code

markStart = millis();

.................... // some time later

timeElapsed = millis() - markStart;

The unsigned subtraction will always give the difference from now time back to that marked time. Rollover does not affect the result but the maximum interval you can time is 49.71-some days.