timer

Development Boards Arduino
1

hello,

i want to know how we can run a loop for specified time and then after the time ends it show us the result.

e.g = we have two variables “a=0” and “b=0” and i want to run program for 5 minutes and when someone press 1 it increments in “a” and when someone press 2 it increments in “b” and then after 5 minutes the loop ends and it print out us value of “a” and “b”. this way we will know how many times 1 is pressed and how may time 2 is pressed.

thanks.

2

Search is your friend. You might find the technique used here works for you:

https://forum.sparkfun.com/viewtopic.ph … er#p153727

3

For measuring seconds I have created an ISR interrupt routine at 50 Hz running on a 8mHz processor ATMega328p

void setupTimer()
{
  // Timer 1 is se to CTC mode, 16-bit timer
  TCCR1B = (1<<WGM12) | (1<<CS11);  // prescaler 8 for Timer
  OCR1A = 20000;                    // Timer 20.000 = 20ms repeat time
  TIMSK1 = (1<<OCIE1A);             // Enable interrupt on compare
}

Now we can use this to count time:

ISR(TIMER1_COMPA_vect)
{
count = (count + 1);			// prescaler from 20ms to seconds
if (count >= 50)
	{
	time = (time + run); count = 0;	// counts seconds when running, resets counter 
	}
}

In the main program you can change the value of run and time depending what you want to do.

run = 1; starts counting time in seconds

run = 0; stops counting time in seconds

time = 0; count = 0; resets time

Be aware that interrupts have priority so before using the variables used in the interrupt routine you should stop the interrupts and allow interrupts after you used this variable

4

An interrupt would work, but for most applications I think this would be easier to implement by sticking to standard Arduino functions.

Mee_n_Mac nailed it - using [millis() or [micros() to check the time on every loop and terminate if a target is exceeded may be the easiest way to approach the problem.](http://arduino.cc/en/Reference/Micros)](millis() - Arduino Reference)