[Kevin] attached a MicroSD breakout board to an Arduino-compatible clone. When the clone starts up, it searches the SD card for a file called ‘program.hex.’ ...

The IDE to SD Card Adapter is available to buy online for $24.99 (about £12.50). You can find out full details on the device over at their website.

This isn't much different, and whether you are doing it to free up a USB port, or because you want to install an OS on your 16GB SD card, its not too expensive for what it does.

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 ...

A maker developer has squeezed an Arduino onto an SD card. His aim was to go one better than Intel’s Edison. Already dubbed SDuino, it is kodera2t’s entry for the Hackaday Prize. “Once I was excited ...

General issue report Description: I’m trying to use the SPI SD card example from ESP-IDF to mount a micro-SD card via an SPI SD card module. It works fine using Arduino-ESP32, but fails in ESP-IDF.

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.