So why does Raspberry Pi use more than 3V? Well, here’s a good answer.
20160731/http://raspberrypi.stackexchange.com/questions/46765/why-do-the-pi-gpio-pins-use-give-3-3v-and-not-5v
- UPDATE 2019-11-20: The primary reason why Raspberry Pi Zero has 5 V power input is because that is the voltage that is required for USB and HDMI. If you do not use those services, as I explain later, you can run straight off of 3 V.
JJJ TODO LINK TWO-WAY!!!