Adding an RTC (real-time clock) is an interesting thought.

By the way, this design is for an Arduino-based technology demonstrator for a meso-scale circuit technology.

I'd like the uC to sleep for 1s.  Most of the time, it would wake up, briefly check if there are inputs, sleep again.

I suppose, I could make this circuit, if nothing else.


But in truth, cyclic sleep is my plan B.  I'm doing a little survey of what Arduino/ATmega can do in the sleep department.  (Myself, I'm a PIC and MSP430 guy most of the time.)
Plan A is to wake up the controller through Anaren radio and external interrupt.

- Nick

Colleagues,

Is it possible to put Arduino into cyclic sleep and wake up periodically from Timer0, Timer1, Timer2 interrupts?  I’m especially interested in Timer1, because it can be set to overflow over longer period.

Here’s what I know so far:

•   It’s possible to do cyclic sleep with a WDT (watch dog timer).  WDT period can be up to 8s.  WDT can wake the Arduino from SLEEP_MODE_PWR_DOWN (the deepest sleep).  This doesn’t sound too bad.  The only down side is that contents of RAM are lost when WDT bites back.  After a reset, the code should figure out whether it’s WDT reset or fresh power-up.

•   I’ve read that Timer0-Timer2 are disabled in SLEEP_MODE_PWR_DOWN.  But in shallower sleep modes, timers should be enabled.  Couldn’t verify this myself, though.  Wrote a small test code, which - depending on the sleep mode - either doesn’t go to sleep, or doesn’t wake up from timer interrupt.  (I can post the code, for what it’s worth.)

Any suggestion, insight or reference is really appreciated!

Happy New Year!

- Nick

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