Supports Micro Crystal RV-1805-C3 extreme low power RTC module.

Search the library using the Library Manager of Arduino IDE, or download it directly via GitHub.

Connect an RV-1805-C3 device to your Arduino board according to the datasheet. There are three examples that come with the library:

• SetDateTime: Configures date and time to the RTC module via the serial console, and then prints the current date and time in ISO 8601 format every second.
• AlarmInterrupt: Sets an alarm based on calendar date and time, and triggers an interrupt.
• CountdownTimer: Sets a repeating countdown timer that triggers an interrupt.

You can find more API functions in src/RV1805C3.h, which are pretty much self-explanatory if you have read the datasheet.

This library has been tested on ESP8266 only. However, it should also be compatible with any architecture that provides Wire.h I²C support.

MIT