The WDT is a bit power hungry.
Another possibility is to use a micropower reset chip and an RC
network to make a long-duration software-controllable one-shot to
provide a wakeup

On Fri, 21 Jun 2002 10:56:40 -0600, you wrote:

>At 11:54 PM 6/20/02 -0300, Gabriel Caffese wrote:
>>Hello everyone,
>>
>>         I have a project where I have to take GREAT care of battery =
life.
>>         It=B4s a portable system with a 16F627, that has to make some=20
>> measurements
>>every
>>          300 seconds, and stay on for 20 seconds.
>>         Once the system is turned on, it will NEVER be turned off.
>>         So, system=B4s life depends on batteries life. When batteries =
die,=20
>> the whole
>>system is disposed.
>
>How accurate does the 300 seconds have to be?  If you can tolerate some=20
>variation, I would consider using the watchdog timer.  You will have to=20
>calibrate the watchdog on a periodic basis - this is easily done by =
setting=20
>the watchdog to no pre-scaler, running the PIC, then timing how long it =
for=20
>the watchdog to trigger.  Use that measured time as the basis for =
setting=20
>how many watchdog timeouts you need to achieve 300 seconds.
>
>dwayne
>
>--
>Dwayne Reid   <dwayner@planet.eon.net>
>Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
>(780) 489-3199 voice          (780) 487-6397 fax
>
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