Arduino Data Logger Shield with RTC and SD Card Interface

Turning an Arduino into a proper data logger

This data logger shield combines two things a real logging project needs: reliable storage and accurate timekeeping. Its SD card interface works with FAT16 or FAT32 formatted cards, and includes 3.3V level shifter circuitry that protects the card from the voltage mismatch that can otherwise damage an SD card connected directly to a 5V Arduino. Data saved this way can be read back later by most plotting, spreadsheet or analysis programs, since it's stored as ordinary files on a standard SD card rather than a proprietary format.

Alongside the SD card interface sits a real-time clock, which keeps ticking even when the Arduino is unplugged or between logging sessions, backed by a battery that lasts around 2 years, so every logged data point can be timestamped accurately without the Arduino needing to be told the current time each time it starts up.

Setup and build

Included libraries and example code for both the SD card and RTC functions mean a working logging setup can be running quickly, without writing low-level SD or RTC handling code from scratch. An onboard 3.3v regulator serves double duty, acting as a reliable reference voltage for the shield's circuitry while also reliably powering the SD card itself.

A prototyping area on the shield gives room to solder additional connectors, circuitry or sensors directly onto the board, useful for adding whatever sensor a specific logging project actually needs to read. It works with Arduino UNO, Duemilanove, Diecimila, Leonardo, or ADK/Mega R3 and higher.

Who it suits

Anyone building a weather station, an environmental monitor, or any project that needs to record sensor readings over time with an accurate timestamp will find this shield combines the two essential pieces, storage and timekeeping, on a single board.

Questions buyers ask

What card formats does it support?

FAT16 or FAT32 formatted SD cards.

Does the clock keep running when the Arduino is off?

Yes, a backup battery keeps the RTC running for about 2 years.

Which Arduino boards is it compatible with?