Simple library for timing in milliseconds, works with Atmega328P, Arduino UNO, may work for other AVRs. Uses TIMER0 and interrupts, can be easily modified to run on any timer, for that see documentation linked below. Timer can run without an overflow for almost 50 days.
void Init(void);Initialisation function, must be called before anything else.
unsigned long Get(void);Read current time.
void Reset(void);Resets milliseconds counter back to zero.
#include "timer.h"
#define DELAY 200 // in ms
Timer timer;
unsigned long lastReading;
int main(void)
{
// setup timer
timer.Init();
unsigned long lastReading = 0;
unsigned long currentTime = 0;
// enable interrupts
sei();
// main loop
while (1)
{
// get time at the start of a loop
currentTime = timer.Get();
// if enough time has passed
if (currentTime - lastReading > DELAY) {
/*
do something (e.g. blink LED)
*/
// reset timing
lastReading = currentTime;
}
}
}