blinking the LED using interrupts

src/timer2_dcc_gen/timer2_dcc_gen.pde

@@ -2,5 +2,45 @@
 // Generating a DCC Signal using Timer2 and the Waveform Generator
 //
 
+#include <avr/io.h>
+#include <avr/interrupt.h> 
+
+#define LED_PIN 5  // digital pin #13 (portb)
+#define LED_ON() PORTB |= _BV(LED_PIN)
+#define LED_OFF() PORTB &= ~_BV(LED_PIN)
+
+byte timer2_target = 128;
+unsigned int mycount = 0;
+
+void setup() {
+
+  // Enable Timer2 
+  OCR2A = timer2_target;
+  bitSet(TCCR2B, CS22);
+  bitSet(TCCR2B, CS21);
+  bitSet(TCCR2B, CS20);
+
+  pinMode(13,OUTPUT);
+
+  // Enable Timer2 interrupt
+  bitSet(TIMSK2, OCIE2A); 
+  sei();  
+}
+
+ISR( TIMER2_COMPA_vect ){
+  mycount += 1;
+
+  if( mycount == 128 ) {
+    LED_OFF();
+  } else if (mycount == 255 ) {
+    LED_ON();
+    mycount = 0;
+  }  
+
+};
+
+
+void loop(){
+}