SD cards can be accessed with two modes. The first is the SDIO mode, which is what cameras, laptops, and other card readers use. The second mode is SPI mode. SPI is slower, but much, much simpler.

[Flux Axiom] is using an Arduino Mega in his setup along with a cornucopia of sensors and all their data is being logged onto an SD card. All the code used in his setup is available in his GitHub ...

A maker developer has squeezed an Arduino onto an SD card. He was inspired by Intel’s Edison compute module and he tried to go one better. The result is the SDuino, an ATMega328P processor-based ...

Meanwhile, the Arduino Mega is getting the same USB chip along with an ATMega2560 processor with twice the memory. Right now only 128K is available, but that's a software limitation and they're ...