The DS-1307 is often the default choice for an RTC. However, if you need advanced features like alarms or square wave outputs, it’s best to look upmarket. The DS1307 has the proud title of being ...

only implementation of a synchronization core allowing to read and write a I2C Realtime Clock (RTC) like the DS1307 or MCP7941x. Access to the RTC is done from the FPGA without software interaction.

For the most part, the build is what you would expect: a 16×8 LED Matrix display driven by a TLC5920 LED driver, with an Arduino that uses a DS1307 RTC (real-time clock) with a coin cell ...