https://wiki.dfrobot.com/dfr0386/
DS1307 RTC Module with Battery for Raspberry Pi | Precise Timekeeping | DFRobot Wiki
Integrate the DS1307 RTC Module with Battery for Raspberry Pi to achieve accurate timekeeping. Compatible with Raspberry Pi models B/A+/B+/2/3/4B. Explore...
rtc module
https://indruino.com/electronics/interface-module/enth-to-uart-rtc
Interface Module : ENTHERNET TO UART/RTC CONVERTER
ENTHERNET TO UART/RTC CONVERTER Interface Module This is a serial TTL to Ethernet module, used for data transparent transmission, converting TCP or UDP socket...
interface moduleuartrtcconverter