The SparkFun OpenLog is an open-source data logger that operates over a simple serial connection and supports microSD cards of up to 32 GB. The OpenLog is capable of storing a significant amount of serial data or "logging" and can serve as a kind of black box to store all serial data generated by your project for scientific or debugging purposes.
The SparkFun OpenLog utilizes an ATmega328 running at 16MHz thanks to its built-in resonator. In idle mode (when there's nothing to log), the OpenLog draws approximately 2-3mA. During full recording, the OpenLog can draw between 10 to 20mA, depending on the microSD card being used.
All data logged by the OpenLog is stored on the microSD card. It is compatible with microSD cards ranging from 512MB to 32GB and supports both FAT16 and FAT32 SD formats.