Quote Originally Posted by flotulopex View Post
Hello,

I need to record temperature & humidity over days with a sample frequency of 15 minutes.

Since the PIC will be battery powered, I think about putting it to SLEEP until the next sample record happens.

According to my PIC's data sheet (16F88 - 4MHz), the TMR0 won't be able to wakeup during SLEEP mode.

What is the best way to time the PIC for long sleep periods?
Watchdog Timer at max time out is about 268 seconds, set up a counter, 3 time outs will get you 13.4 minutes (give or take). The watchdog timer isn't all that accurate. You can however use TMR1 with a low power crystal on it and prescale that a bunch, but again, you'll end up waking every so often and using that same counter to get your 15 minutes.

You could use a 4 wind up clocks and some lever switches to reset your PIC every 15 minutes