I have seen, that on some new µC the biggest disadvantage of internal watchdogs was removed.

Most older internal watchdogs are asleep after reset and can be disabled or stopped.

But now internal watchdogs exist, which can be enabled permanetly during programming the fuse bits.
Then they can never be disabled.
Furthermore they run from a separate internal RC oscillator and thus they are still running, even if the µC was in the sleep mode and main clock source was stopped.

So also internal watchdogs can now be named as useful and an external watchdog was no longer needed.


The only point, the internal µC design must be able to establish a proper power up in any case, e.g. the watchdog enable fuse must always be read correct.


Peter