Ultra low power questions

Making a data logger, like many. So low speed and very low power.
I am using an 3V Pro Mini, DS3231(RTC), SDcard and a Dallas one wire sensor.

So far my low power initiatives are:

  • P-channel mosfet powering SDcard reader when required.
  • DS3231 is modified with LED and charging resistors removed and battery replaced
    with a CR2032 cell and powered on Data pin with resistor and .1 mF cap.

Okay… I have tried and have reviewed on line to make my RTC with no main 3V power
interrupt and wake the Arduino; no success. If anyone has a solution I would like to hear it.

So my current sketch has the following
sleep59(): Sleep the Arduino for 7 X 8 seconds
Sleep 2 seconds and sleep 1 second

Then SleepTillMin(): power up RTC and interrupt on the next min.
i.e. about <1 second later.

anyone got a better solution???

Looks good. Have you achieved your power goal? How far away are you?

(You didn’t tell us what battery you want to use, nor how long it must work between battery changes.)

Have you seen Nick Gammon's low power tutorial?