First version of the blinking LEDS with interrupts.

Blinks on and off every 10 seconds.
Next step is to have day and night cycles

arduino/ledCycleInterrupt/ledCycleInterrupt.ino

@@ -0,0 +1,48 @@
+// Arduino timer CTC interrupt example
+//
+// avr-libc library includes
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#define LEDPIN 8
+
+volatile byte seconds;
+
+void setup()
+{
+  pinMode(LEDPIN, OUTPUT);
+  // initialize Timer1
+  cli();          // disable global interrupts
+  TCCR1A = 0;     // set entire TCCR1A register to 0
+  TCCR1B = 0;     // same for TCCR1B
+  
+  // set compare match register to desired timer count:
+  OCR1A = 15624;
+  
+  // turn on CTC mode:
+  TCCR1B |= (1 << WGM12);
+  
+  // Set CS10 and CS12 bits for 1024 prescaler:
+  TCCR1B |= (1 << CS10);
+  TCCR1B |= (1 << CS12);
+  
+  // enable timer compare interrupt:
+  TIMSK1 |= (1 << OCIE1A);
+  
+  // enable global interrupts:
+  sei();
+}
+
+void loop()
+{
+// main program
+}
+
+ISR(TIMER1_COMPA_vect)
+{
+  seconds++;
+  if(seconds == 10)
+  {
+    seconds = 0;
+    digitalWrite(LEDPIN, !digitalRead(LEDPIN));
+  }
+}