No, that's the phone itself transmitting in its TDMA timeslots. https://en.wikipedia.org/wiki/Time-division_multiple_access#...

Otherwise great post, though I'd love to have seen the images!

https://web.archive.org/web/20210615000000*/https://makecade...

* https://minac.github.io/2015-05-20-s3-cloudfront-access-deni...

It can sleep and only use ~66 microamps at 5V with the watchdog timer enabled. That's 330 microwatts. A 1000 mA lithium cell (3.6 watt-hours) could then run it for ~10909 hours, or 454 days (~1 1/3 years).

Almost every microprocessor made these days has some sort of low-power sleep. The ATmega series aren't even particularly good at being low-power.

Of course, you then realize the "arduino" is really just a badly designed development board for an atmega, and they went and used cheap voltage regulators that have an idle current consumption of > 1 mA, and give up on the whole project.

i.e. https://ww1.microchip.com/downloads/en/devicedoc/39941d.pdf

For more standard cases, the 43uA from the article is roughly the same order of magnitude you'll get from pretty much any micro in sleep mode, after doing your first pass low power optimisation. The stuff I normally work with gets about 10. The thing is just, most of the time, that's low enough already - for this project 2500mAh/43uA = 6 years of sleeping. The bigger factor is the current it consumes while awake - and that's where the Arduino's a bit of a letdown, the stuff I normally use is only in the order of 100uA while awake.