Finally worked out deciseconds

Makefile.avr

@@ -39,4 +39,4 @@ clean:
 
 
 
-	
+	

blink.c

@@ -1,39 +1,42 @@
 #include <avr/io.h>
-#include <util/delay.h>
- 
- 
-int main (void)
+#include <avr/interrupt.h>
+
+/* This only works out for a 16MHz or 8MHz clock */
+#define CLOCK_HZ 16000000
+#define TICKS_PER_SECOND (CLOCK_HZ / 256)
+#define TICKS_PER_JIFFY (TICKS_PER_SECOND / 10)
+
+volatile uint32_t jiffies = 0;
+
+ISR(TIM1_COMPA_vect)
 {
-  unsigned char counter;
-  /* set PORTB for output*/
-  DDRB = 0xFF;
- 
-  while (1)
-    {
-      /* set PORTB.2 high */
-      PORTB = 0xFF;
- 
-      /* wait (10 * 120000) cycles = wait 1200000 cycles */
-      counter = 0;
-      while (counter != 10)
-	{
-	  /* wait (30000 x 4) cycles = wait 120000 cycles */
-	  _delay_loop_2(30000);
-	  counter++;
+	jiffies += 1;
+}
+
+int
+main(void)
+{
+	unsigned char counter;
+
+	/*
+	 * set PORTB for output
+	 */
+	DDRB = 0xFF;
+	PORTB = 0x00;
+
+	TCCR1A = 0;
+	TCCR1B = 0;
+	TCNT1 = 0;
+	OCR1A = TICKS_PER_JIFFY - 1;
+	TCCR1B |= (1 << WGM12);
+	TCCR1B |= (1 << CS12);
+	TIMSK1 |= (1 << OCIE1A);
+
+	sei();
+
+	while (1) {
+		PORTB = 0xFF * ((jiffies/ 10) % 2);
 	}
- 
-      /* set PORTB.2 low */
-      PORTB = 0x00;
- 
-      /* wait (10 * 120000) cycles = wait 1200000 cycles */
-      counter = 0;
-      while (counter != 10)
-	{
-	  /* wait (30000 x 4) cycles = wait 120000 cycles */
-	  _delay_loop_2(30000);
-	  counter++;
-	}
-    }
- 
-  return 1;
-}
+
+	return 0;
+}