You can think of the WDT as a sort of a warm boot mechanism.  It is
designed to restart the processor, but without switching off the
power. A flag in the status register is set when it has been
triggered. When WDT is enabled, a builtin rc oscillator starts and
counts down to zero and reboots.  To prevent a reboot, use CLRWDT
instruction before it can happen.  Whether a watchdog timeout is a
Bad Thing depends on what you want to do.  For example, you can do a
temperature compensation for a pic by measuring how long in
crystal-oscillator ticks it takes to trigger the WDT, then adjust a
timing loop so it remains constant as the RC oscillator changes with
temperature, since sleep uses the RC oscillator.

it is tricky to learn, you need to experiment with loops that time
out on purpose to get a feel for it, and a way to reliably detect
whether the WDT occured or something else happened.

alice
>
> Can somebody please explain what is the watch dog timer and its uses...
> thanks.
> regards
>
>