This sketch is for a DigiSpark ATTiny85 or AdaFruit Trinket
Acts as a hardware watchdog on any host that has a reset pin which functions by being pulled LOW to ground.
Monitors hbPin, requiring a state change within hbTime.
Onboard LED mimics the state of the hbPin signal from the host, giving a visual heartbeat of both hosts with one LED.
If a state change is not detected, resetPin is pulled LOW to force a reset on the host. ResetPin on the watchdog needs to be connected to the RST pin on the host and both devices need to be on a common ground.
Can be used in conjunction with - https://github.com/sktaylortrash/HeartBeat
Dependant Libraries
http://playground.arduino.cc/Code/SimpleTimer
