Steve, I need sleep to really conserve power. This thing gets its power from photovoltaics in daylight. It stores Vcc in large electrolytic caps!
Also, it only has to operate for about 20 seconds every 15 minutes or so. (wake by WDT) I also need to store data in the eeprom - but nothing in the registers can reset when it goes to sleep. Using sleepuncal to do that. Don't give a flip about the actual sleep time tolerance. I Think it will work, but not sure yet!!
Thanks
Ron