Self-waking PIC

Hi all,

Is there anyway that a PIC in sleep mode can wake-up periodically by way of an internal mechanism (say, every 30 seconds), perform a short routine and then re-enter Sleep again?

I'm using a 16F505, but this has no interrupts so I was wondering if I could use the internal timer to implement this function? I know the wake-up on input change would suit but this would mean adding an external timer and the loss of an I/O pin.

If this is not possible with the 505, is it possible with any other PIC and if so, do I still have to externally generate an interrupt every 30 seconds?

Thanks for any help, Simon

Reply to
PigPOg
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Hi Simon,

PigPOg schrieb:

Enable the watchdog, setup the wdt prescaler as you prefer. Every watchdog trigger puts the device out of reset. You can determine a WDT reset from a power-on-reset by using some STATUS bits provided. I have done that, works great. If you like some more details -> PM me (see below).

HTH Wolfgang

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Reply to
Wolfgang Mahringer

Wolfgang,

Thank you for the suggestion - I have no idea why I didn't think of this! It's the perfect solution for me.

Thanks once again, kind regards, Simon

Reply to
PigPOg

If you need really really low power draw, look at the nanopower devices like the

16F636 - these have a watchdog postscaler that allows WDT periods up to a few minutes, and have much lower watchdog current - about 3uA
Reply to
Mike Harrison

the 16F636 - these have

much lower watchdog

I'll follow that up - thanks Mike.

Simon

Reply to
PigPOg

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