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Thread: Where to put CRLWDT?
www.piclist.com/techref/index.htm?key=where+put+crlwdt
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face BY : John Payson email (remove spam text)



|Under certain circumstances, it may be permissible to allow the WDT to
|reset your code periodically.

If periodic forced resets are acceptable, it may be useful to
have external hardware to enforce them.  For top reliability,
you may want to have an external device control the PIC's power
so that even if it goes into CMOS latch-up, it will come out of
that condition "guaranteed".  If your code is supposed to do a
tiny bit of work once per second, you could use a simple timer
circuit to turn the PIC on for 3/4 second and off for 1/4 second
or somesuch.  As a slightly-related alternative, you could have
your external hardware pull down on MCLR briefly while discon-
necting the supply to the PIC's bypass/filter caps; if the PIC is
not in CMOS latchup, decent-sized caps may keep it powered enough
to maintain RAM contents, but if it goes into CMOS latchup the
caps would drain out and the device would get a true power-down,
thereby ending the latch-up condition (internal RAM contents would
be hosed in such a case, naturally, but the device would still be
operable).

<01BDED28.3E3EA6D0@JOHN_WKST1> 7bit

See also: www.piclist.com/techref/index.htm?key=where+put+crlwdt
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