I am interested in adding a real time clock (RTC) to the RPi. Core Electronics has so many RTC clocks available for sale at Core. Search for real time clock and there are 26 results. I have found the following features.
- breakout - all the boards seem to be breakout.
- communication to and from breakout - SPI, Are there IIC?
- button battery or running from the 5V or 3,3V supply - do all the RTC breakout boards have provision for a button battery? Or in other words, when the 5V or 3.,3 is off, do all breakout RTCs go to the button battery OR is it only some RTCs have provision for a button battery?
- accuracy - which are the least accurate and which are the most accurate
Please assist,
Thank you,
Anthony
