PeterH:
Doesn't this assume that the board remains capable of handling watchdog interrupts? There are failure modes where that would not be the case, so as a hard recovery option this would be less robust than using a watchdog to trigger a reset directly.
FWIW, according to the datasheet, using the watchdog interrupt can be useful for things like saving essential data before reset. So apparently someone at Amtel thought that watchdog interrupts would be at least somewhat reliable.
What failure modes might cause the board to not be able to handle watchdog interrupts? Is there a failure mode that might corrupt the watchdog status registers and control bits, too, thus killing the dog and its reset capability, too?
Using external components to reset after inactivity would be the most reliable approach. I don't need that for this project.