At 04:34 PM 11/7/97 -0600, Gennady Palitsky wrote:
>I am back with the question on PIC and power consumtion. I need to make
>measurements with PIC every 5 minutes, keeeping power consumption to the
>minimum between measurements. My first thought - to turn power to PIC
>off and to turn it on by external timer (what is 50-100 uA by itself).
>Does anybody know of better way to do it? And second - how can I keep
>track of what PIC is doing if I power it off and don't use NVRAM?

One solution that springs to mind is to use a seperate real-time clock module.
 If you put the PIC to sleep, and use the watchdog to wake up periodically and
 check the current time, that would probably keep power consumption to a
 minimum.  If the PIC's own EEPROM doesn't give you enough non-volatile storage,
 you might try one of the many I2C serial EEPROM chips.  You could power it up
 using a PIC port pin only when needed to further reduce power consumption.

I guess a lot depends on the accuracy of timekeeping needed.  If the 5-minute
 interval is somewhat flexible, you could simply count watchdog resets, and
 approximate your 5 minutes without adding an extra chip (the RTC module).

Hope this helps,

 - Rick "Pic'n up speed now" Dickinson

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