Elastic Sheep

Could be useful sometime in the future:
http://wiblocks.luciani.org/docs/app-notes/software-reset.html

#include <avr/wdt.h>
 
void reboot() {
  wdt_disable();  
  wdt_enable(WDTO_15MS);
  while (1) {}
}

The watchdog is enabled with the minimum time-out of 15ms. Then a system reset is triggered when the time-out is reached.

Note: the reset source can be determined at boot time by reading the MCUSR register (watchdog system reset, brown-out reset, external reset or power-on reset).