Possible to power RTC separately?

Using Arduino Project Guidance
1

Hi all

I am building a watch with a mini arduino. I have found that the ATMega328 has a built-in RTC, which is great, but I have a question involving its usage.

I would like to be able to power this RTC without powering the arduino. Why? If the watch user just doesn't charge their watch, I want the RTC to still keep time, even when the arduino goes into sleep mode (since I'm using LiPo batteries, and need to go into low power mode when the charge is low). I'm hoping that this can be done like it is in a watch; that is, using a button cell.

Is this possible, or should I use an external RTC module?

2

The SAM3x in the Arduino Due has a built-in RTC. The ATMega328 in the Arduino Uno doesn't.

On the Arduino Due boards, it's impossible to use the RTC as there is no crystal for it and the independent power supply isn't set up.

Get an external RTC module.