On Tue, Jan 24, 2006 at 09:45:08AM +1300, Jinx wrote:
> > I'll be running my PIC chip at the absolute lowest possible
> > speed. It doesn't take much processor power to count
> 
> BTW, I didn't mention what I thought might be the lowest Iq
> option
> 
> The alive part of the circuit could be the guts from a digital
> watch without the display. I've got a tiny one on a shelf in
> the shed that goes for years off a button cell, and it would go
> for even longer without the LCD. If you got one that has a
> daily alarm to wake the PIC, that's very slow counting

Absolutely. I've seen papers on the designs of those things... Just
insane. It really makes me want to try another posters suggestion of
running it off of RF, like an old crystal radio.

Perhaps I could use a pre-built RTC? I vaguely remember seeing some
reference timed alarms in their datasheets... Have the RTC turn the PIC
on every week or something.

My understanding is that much of the ability of watch circuits and what
not to operate at such low power is controlling leakage currents. It's
why you can never make a modern CPU operate at nanowatts, the process
technology just won't allow it. PICs are pretty good, but I can only
assume even better would be something designed to run at 32khz rather
than up to 20mhz...

-- 
pete@petertodd.ca http://www.petertodd.ca
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist