Giving an Arduino a Heartbeat

How would one be able to restart a system that has been deployed in a remote area which gives no immediate access for human intervention? The answer is to give the system an ability to reset itself in case of a system crash. This is where a watchdog timer (WDT) comes into use. It is a hardware based timer capable of automatically resetting a system should the main program fail to periodically send out a heartbeat. Now, the Arduino does indeed have a WDT on board, as do probably all microcontrollers, but a small amount of reading will inform you that once it has started running a sketch, there is no software function that has the same effect as pressing the reset button.”