I'm developing a product, that basically makes a measurement every day, and sends it over a network.
Measurement implies to act on a stepper motor, and use the analog input.
Network can be wifi (esp8266 as slave, or master MCU), GSM, or LPWAN (sigfox/lorawan).
Targeted power supply would be most available AA alkaline batteries, 3 or 4 of them (is it enough current for GSM? not tested yet, but at least ok for wifi and lpwan)
And the goal is to maximize battery life.
Energy optimization includes many factors, but one important is the current consumed in standby state between two measurements.
After some prototype with off-the-shelf boards, I started to create a custom board.
Strategy I chose for my 'deep sleep' function, is to use an external RTC, with a wakeup function. I chose in function of timekeeping current, price, etc.... : NXP's PCF8523, => 150nA on paper, 0.1µA measured (the minimum measurement of my basic multimeter).
This RTC is supplied directly by main batteries, no additional coin battery, and no energy-costly voltage regulator.
The wake up pin directly trigger the enable pin of my voltage regulator (LM3671, 3.3V output), this chip drinks 10nA in off state.
160nA sleep current on paper, pretty nice, uhh? Probably much less than self-discharge current of my battery.
Well, for a few reasons, I'm considering abandoning the idea of a custom board. (project will be more DIY-friendly with off-the-shelf boards, easier to switch to the next technology with modular shields, and I don't spend energy on producing custom boards)
Arduino UNO became de facto the standard for the idea of stacking up shields. Even if the MCU board is not an arduino, or even not with an ATMEGA328.
In this UNO shield format, I'll easily find a motor shield, GSM shield, Wifi shield, lora shield, sigfox shield, and the next-future-technology shield (5G?).
What I do not find, and I finally come to my root question, is a shield to do an efficient power management by waking up (and powering) the rest of the stack on a regular basis.
Datalogger shield that I find (adafruit) have an RTC (and the good one : PCF8523), have an SDCard slot (which might be an interesting option for me), but don't have the power management part.
For a prototype, I could easily add this feature to the adafruit board by adding my battery input and a mosfet or kind of SSR. But I'm potentially targeting people without soldering iron...
I'd be really surprised if I were the first to have this need....
If it really doesn't exist, but you think it might be interesting... we could push the idea to some shield maker (arduino/adafruit/sparkfun)
Many thanks, Pierre