How to put your Arduino to sleep to save power (and wake up again)
See the accompanying videos #115 & #116 at https://www.youtube.com/ralphbacon
(Direct link to part 1 video: https://youtu.be/jqFl8ydUzZM)
(Direct link to part 2 video: https://youtu.be/8fiYvnBDsDE)
Note: the video to actually construct the bare bones Arduino (using an ATmega328P chip and a handful of components) can be found in this GitHub repository under Bare Bones Arduino https://github.com/RalphBacon/Bare-Bones-Arduino, see YouTube video #117.
There are two ways to put your Arduino ATMEGA328P (UNO or Nano, for example) to sleep - or more accurately, two ways to wake it up after it has been put to sleep in order to save (battery) power.
So we have TWO sketches here: one to wake up using a switch (which triggers an INTERRUPT), and another to wake up every few seconds (8 seconds max) using an inbuilt TIMER.
They are very similar and I suggest you start with the interrupt driven one first (using two switches) as it's easier to get your head round what's actually going on!
It's all very well saving power by putting your ATMEGA328P board to sleep, but what are we going to do about the supporting circuitry? We cover that in part two by putting together a bare-bones Arduino using a handful of components. Easy to do and cheap.
Also, have a look at Thijs Ruiter's Kickstarter campaign - if he reaches his goal I'll do a proper review of his sound module:
http://kck.st/2M2KeRr
The 18650 Battery Charge Shield:
https://www.aliexpress.com/item/ESP32-ESP32S-For-Wemos-For-Raspberry-Pi-18650-Battery-Charge-Shield-Board-V3-Micro-USB-Port/32870411748.html
The official ATmega28P data sheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega328_P%20AVR%20MCU%20with%20picoPower%20Technology%20Data%20Sheet%2040001984A.pdf
The FP6298 PWM converter datasheet:
http://www.feeling-tech.com.tw/km-master/ezcatfiles/cust/img/img/24/fp6298v063.pdf
Arduino pin mapping (GPIO numbers vs Chip numbers):
https://www.arduino.cc/en/Hacking/PinMapping168
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