Old hat I think, as the 3v coin cell battery of a DS3231 is capable of being triggered by the alarm function to turn the battery power on to the pico via a mosfet transistor to awaken the pico to do whatever and then the pico can set the next alarm time and power down completely. Whether much, if any, is gained by the complete power down v a deep sleep would depend on the difference in power consumption for a cold restart against a slumber restart and the frequency of the power cycle.
I tried this power off with a DS3231 a couple of years ago in a scenario where the pico was woken up every 15 minutes, but the process of taking a few sensor reading, connecting to wifi, and sending mqtt messages took about 30 seconds if memory serves me well. It may have been a bit longer, and the 3 AA battery pack only lasted about a month and a half. I probably could have been more frugal on the use of the pico power on time, but I changed tack and laid on a POE cable to the location. Good old sledge hammer to crack the nut![:D]( "Very Happy")
I tried this power off with a DS3231 a couple of years ago in a scenario where the pico was woken up every 15 minutes, but the process of taking a few sensor reading, connecting to wifi, and sending mqtt messages took about 30 seconds if memory serves me well. It may have been a bit longer, and the 3 AA battery pack only lasted about a month and a half. I probably could have been more frugal on the use of the pico power on time, but I changed tack and laid on a POE cable to the location. Good old sledge hammer to crack the nut
Statistics: Posted by SirFico — Mon Jan 12, 2026 9:51 pm