More info that I should've added before ...
- PIC 16F628.
- Internal oscillator at 4Mhz.
- Also 32.768khz oscillator on Timer 1.
- Comparator off.
- WDT off.
- Timer 0 automatically off during sleep
- Timer 1 oscillator on during sleep
- Timer 2 off (by default)
- CCP off (by default)
- V.Ref off (by default)
- UART off (by default)
- PWRT on
- BOD off
- MCLR disabled (I'm using RA5 as an input)
- Port B pull-ups explicitly set off.
- 5V supply.  I'm measuring current at the output of the 7805.

BTW, I'm using a super-duper high-class Radio-Shack mutltimeter, so the 0=
=2E12mA=20
figure may have a noticeable tolerance.  I expect this to be significant =
at=20
these lower mA values, but hopefully the error is not in the hundreds of=20
percent!  =3D8-0

Schematic ...
   http://www.narwani.org/neil/stuff/WST1.00_revA.gif

Before the sleep instruction, RA4 is explicitly set to "1", and all other=
=20
outputs are set to 0.  RA5 is the only input, and externally pulled to=20
ground.

Cheers,
-Neil.




On Friday 20 June 2003 14:24, Picdude scribbled:
> Hi all,
>
> Got my timer/clock working and tuned down for low power, but from vario=
us
> archive posts, I feel like I should be able to go lower.  In a nutshell=
,
> think of it as a digital clock w/3 switches, 4 LED digits and a buzzer.
> Normal operation is internal clock at 4Mhz, AND external osc (Timer 1) =
at
> 32.768kHz.  There are 2 modes -- normal and sleep.
>
> In normal operation, I get ~52mA.  No prob.
>
> In sleep mode, the internal osc is shut down and all LED's are off, and
> only Timer 1 wakes up every 1/2 second (which wakes up the internal osc=
),
> runs about 50 instructions and goes to sleep.  During all this time, RA=
4
> (open drain) is such that it draws no power during the brief wake up.  =
In
> this mode, I get 0.12mA average.
>
> Is lower possible?  Or am I asking too much?  I don't *need* it to be l=
ess,
> but would be nice to know/learn if any other optimizations are possible=
=2E
>
> Cheers,
> -Neil.

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