I would like to control the activation of a Pico using the PiicoDev or Makerverse RTC.
Unfortunately the RV2038 RTC generates a low interrupt output and both Makeverse Nano power timers require a high logic level for the power to be switched on.
I’m currently wiring up a Sparkfun Battery Babysitter to be controlled by the Makerverse RTC - incurring the usual mechanical hassles.
While doing so, it occurred to me that a version of the Makerverse Nano power timer HAT using the already available Makerverse RV2038 logic instead of the current clunky timer logic would offer a better way to control the scheduling logic in a sensor monitoring environment.
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Hi Roger - sounds like you’re onto something!
I’m not sure if the RV-3028 will generate interrupt signals while only powered by the backup capacitor. It sounds like you want to generate an interrupt signal to trigger a power-on.
Something to look up in the datasheet might be whether the RV-3028 requires full Vcc for that behaviour.
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G’day Michael,
It specifically mentions in the application manual that the interrupt is available when in backup state. The documentation seems to indicate that the interrupt is action is performed by means of a MOS-FET pulling an externally supplied load to ground.
I’m actually preparing for a breadboard test of the interrupt at the present time.
I’ll keep you posted on my progress which, however, is often delayed by higher priority (non-electronic) interrupts.
Oh great @Roger74966 
Looking forward to hearing about the outcome.
G’day Michael,
Hmm… this project has taken a long time - lots of breaks.
I now have a functioning time-switched battery power saving control for my Pico project.
It consists of a Makerverse USB-C LiPo charger which provides permanent power from the connected battery to a Makerverse RTC RV3028 and a Polulu MOSFET Slide switch (LV) 2810. The latter has a low active “switch” input and a high active “ON” input. Power is switched on to the Pico when an alarm condition in the RTC causes the RTC INT pin to go low. The Pico holds the switch ON input high to ensure that switch remains ON regardless of the state of the RTC INT output. The remainder of the connected circuitry is powered from the Pico.
I’d like to make a block diagram of it. Do you have any suggestions for a suitable application to do that? (Preferably for MS-Win but for Linux is OK too)
Hi @Roger74966 - I’ve been out of the office for a few weeks so apologies for the lengthy delay there!
Sounds like great progress, and a useful, flexible approach that can be used in many projects
If all you want to make is a block diagram there are plenty of (free) illustrating programs like;
KiCad, is my go-to for schematic and PCB design. Its a free, open source PCB design tool, but has schematic tools that are useful for block diagramming as well.
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Thanks Michael, I’ll check them out.
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