/*
 * main.c
 *
 * Created: 4/3/2014 8:36:43 AM
 *  Author: razius
 */

#include <avr/io.h>
#include <avr/interrupt.h>

uint8_t SECONDS = 0x00;

int main(void){
    // Clear Timer on Compare Match (CTC) Mode with OCRnA as top.
    TCCR1A |= _BV(WGM12);

    // clk / (2 * prescaler * (1 + OCRnA))
    OCR1AH = 0x7A;
    OCR1AL = 0x12;

    // Setup Timer 0 pre-scaler to clk/256
    TCCR1B |= _BV(CS12);

    // Enable Timer/Counter4 overflow interrupt.
    TIMSK1 = _BV(TOIE1);

    // Setup PH3 to output
    DDRH = 0xFF;

    // Enable MCU interrupt (set I-flag)
    sei();

    while (1) {
        PORTH = ~SECONDS;
    }

    return 0;
}

ISR(TIMER1_OVF_vect){
    // Setup PH3 to output
    // DDRH |= _BV(DDH3);
    // PORTH = PORTH << 1;
    if (SECONDS < 60) {
        SECONDS++;
    }
    else {
        SECONDS = 0x00;
    }
}

/*
 * main.c
 *
 * Created: 4/3/2014 8:36:43 AM
 *  Author: razius
 */

#include <avr/io.h>
#include <avr/interrupt.h>

int main(void){
    // Clear Timer on Compare Match (CTC) Mode with OCRnA as top.
    TCCR4B |= _BV(WGM42);

    // Toggle OCnA on compare match
    TCCR4A |= _BV(COM4A0);

    // clk / (2 * prescaler * (1 + OCRnA))
    OCR4AH = 0x7A;
    OCR4AL = 0x12;

    // Setup Timer 0 pre-scaler to clk/256
    TCCR4B |= _BV(CS42);

    // Setup PH3 to output
    DDRH |= _BV(DDH3);

    // Enable MCU interrupt (set I-flag)
    sei();

    while (1) {
    }

    return 0;
}

--- 
+++ 
@@ -8,28 +8,43 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
 
+uint8_t SECONDS = 0x00;
+
 int main(void){
     // Clear Timer on Compare Match (CTC) Mode with OCRnA as top.
-    TCCR4B |= _BV(WGM42);
-
-    // Toggle OCnA on compare match
-    TCCR4A |= _BV(COM4A0);
+    TCCR1A |= _BV(WGM12);
 
     // clk / (2 * prescaler * (1 + OCRnA))
-    OCR4AH = 0x7A;
-    OCR4AL = 0x12;
+    OCR1AH = 0x7A;
+    OCR1AL = 0x12;
 
     // Setup Timer 0 pre-scaler to clk/256
-    TCCR4B |= _BV(CS42);
+    TCCR1B |= _BV(CS12);
+
+    // Enable Timer/Counter4 overflow interrupt.
+    TIMSK1 = _BV(TOIE1);
 
     // Setup PH3 to output
-    DDRH |= _BV(DDH3);
+    DDRH = 0xFF;
 
     // Enable MCU interrupt (set I-flag)
     sei();
 
     while (1) {
+        PORTH = ~SECONDS;
     }
 
     return 0;
 }
+
+ISR(TIMER1_OVF_vect){
+    // Setup PH3 to output
+    // DDRH |= _BV(DDH3);
+    // PORTH = PORTH << 1;
+    if (SECONDS < 60) {
+        SECONDS++;
+    }
+    else {
+        SECONDS = 0x00;
+    }
+}
Increment seconds and show them using LED's.
