The RTC you ... in special modules designed for the Raspberry Pi’s particular form factor. They’re available in all kinds, from the humble DS1307 to the razor-sharp DS3231.

[Pete] wondered how real-time clock modules could be selling on eBay for $1.50 when the main component, the Maxim DS3231 RTC/TCXO chip, cost him more like $4 apiece. Could the cheap modules ...

Developers, makers and hobbyists looking for a real time clock module complete with an Arduino library, may be interested in the Kraztech Real Time Clock Module created by developer Christopher ...