Replacing SD Card Readers with SD NAND Chips

Adding an SD card reader to a circuit is an easy way to add tons of storage for your electronics projects. It is an inexpensive solution, and existing libraries make reading and writing data on SD cards a snap. But when size is a big consideration, an SD card reader could be too bulky. As small as they are, they aren’t well suited for the tiniest of projects.

If you find yourself in this situation, there is a simple solution that was recently pointed out by DIY GUY Chris. Chris built a custom breakout board that uses a tiny NAND flash chip that can be accessed in the same way as a traditional SD card. Using this board—or a similar one of your own design—the same existing software libraries can be used, but without a card reader.

The project is built around the XTX XTSD04GLGEAG, a surface-mount NAND flash chip that behaves exactly like a standard removable SD card, but is designed to be soldered directly onto a PCB. Despite its tiny footprint, the chip supports common SD protocols and can be read by computers, 3D printers, and other devices with no special drivers. Once mounted, it effectively becomes permanent storage embedded into the hardware itself.

Chris walks through the full process, starting with the schematic and PCB design. The breakout board is laid out to mirror the electrical connections of a standard SD card while exposing all signals through 2.54 mm pin headers for breadboard use. Special attention is paid to physical constraints, such as using a 0.6 mm-thick PCB so the finished board can slide into a normal SD card reader for testing. Fine trace widths, clear pin labeling, and an ENIG surface finish help ensure reliability and solderability.

Assembly is the most challenging part of the build. The chip comes in a QFN package, requiring solder paste and a hotplate or reflow oven for proper installation. After reflow, the board is carefully inspected under magnification to check for bridges or misalignment before adding the pin headers. While this step requires some patience, it is well within reach of experienced hobbyists.

Once assembled, the board connects to an Arduino using a standard SPI interface and works seamlessly with the popular SdFat library. Chris demonstrates a serial-based menu system that allows users to list files, create and delete text files, write data, and read it back, all from a simple terminal window.

Because multiple interfaces are available, files created on the Arduino appear instantly when the board is plugged into a computer’s SD card reader, and files copied from a PC can be read back by the microcontroller. For data loggers, embedded controllers, or space-constrained designs, this approach offers the convenience of SD storage without the bulk of a socket.