Matthew Miller wrote :

> I tried two experiments. For both I used the 
WDT set the max 
> prescale value
> giving a delay of ~2 sec. The first 
experiment was using the external
> osc. with R=68k and C=0.0001uF; the 
measured instruction 
> clock was around
> 5kHz. During each wake-up 
the LED is turned on for about 4e-4 
> sec. (two
> nop's implimented 
this delay.) Current draw was very small, 
> around 10uA. The
> circuit 
operated for about 30 min. off the initial 3V charge 
> on a 4700uF
> 
cap!
> 
> For the next experiment, I used the 4MHz internal oscillator 
> and a delay
> subroutine to flash the LED on for 4e-4 sec. The 
performance in this
> configuration was much worse than I expected. The 
current 
> draw was around
> 92uA and the circuit only ran for two 
minutes powered by the 
> 4700uF cap.

So at 92 uA instead of 10 uA the 
processor
is doing aprox 800 times as much "work"
(processor cycles)

Not that bad, is it ?


Jan-Erik.



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