Create library for software timers and enable it

main.c

@@ -1,6 +1,6 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
-#include <util/delay.h>
+#include "ptimer.h"
 #include "i2c.h"
 #include "rtc.h"
 #include "led.h"
@@ -11,6 +11,7 @@
 
 int main() 
 {
+  ptimer_init();
   i2c_init(I2C_BITRATE); 
   rtc_int0_init();
   led_init();

ptimer.c

@@ -0,0 +1,23 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include "ptimer.h"
+
+volatile uint16_t timers[TIMERS_COUNT];
+
+void ptimer_init(void)
+{
+  for(uint8_t i=0; i<TIMERS_COUNT; ++i) timers[i] = 0;
+
+  TCCR2 |= (1<<WGM21); // CTC Mode
+	TCCR2 |= (1<<CS22) | (1<<CS21) | (1<<CS20); // Prescaler 1024
+	OCR2 = 78; // ~100Hz
+	TIMSK |= (1<<OCIE2); // Enable CTC interruptions
+}
+
+ISR(TIMER2_COMP_vect)
+{
+  for(uint8_t i=0; i<TIMERS_COUNT; ++i)
+  {
+    if(timers[i]) --timers[i];
+  }  
+}

ptimer.h

@@ -0,0 +1,10 @@
+#ifndef __PTIMER_H__
+#define __PTIMER_H__
+
+#define TIMERS_COUNT 0
+
+extern volatile uint16_t timers[TIMERS_COUNT];
+
+void ptimer_init(void);
+
+#endif