Build Your Own SD Card Chip | Arduino Compatible

Have you ever wanted to integrate permanent storage directly into your PCB designs without using bulky SD card slots? Meet the XTX XTSD04GLGEAG - a tiny SD card chip that works exactly like a standard SD card but can be soldered directly to your circuit board!

In this Instructable, I'll show you how to create a custom breakout board for this chip, interface it with Arduino using SPI, and build a user-friendly serial menu system to manage files. This project is perfect for embedded systems, data loggers, or any application where space is at a premium.

The best part? Once assembled, this chip works seamlessly with computers, 3D printers, and any device that reads standard SD cards - no drivers needed!

Hardware Components:

1. XTX XTSD04GLGEAG SD card chip
2. Arduino board (Uno, Nano, or compatible)
3. Custom PCB (design files provided)
4. 2.54mm SIL pin headers (2x5 pins)
5. Solder paste (type 4 recommended)
6. Soldering iron with fine tip
7. Hotplate or reflow oven
8. Breadboard and jumper wires
9. SD card reader (for initial testing)

Software Tools:

1. Arduino IDE (latest version)
2. SdFat library by Bill Greiman
3. Altium Designer (or your preferred PCB design tool)
4. Serial terminal program (like PuTTY or Arduino Serial Monitor)

Manufacturing Services:

1. JLCPCB or similar PCB fabrication service
2. (Optional) 3D printer for enclosure

Start by designing the breakout board in your preferred PCB design software. I used Altium Designer for this project, but you can use KiCad, Eagle, or any other tool you're comfortable with.

Design Considerations:

1. Create a schematic that duplicates the XTSD chip for top and bottom assembly
2. Connect all chip pins to SIL connectors for easy breadboard compatibility
3. Follow standard SD card layout for the edge connection if you want reader compatibility
4. Set PCB thickness to 0.6mm - this is crucial for fitting into standard SD card readers
5. Use 0.2mm trace width for signal lines
6. Add clear pin labeling for easy wiring reference

Manufacturing Preparation:

1. Generate Gerber files from your design
2. Choose a solder mask color (I went with JLCPCB's signature blue)
3. Select ENIG (Gold Nickel) surface finish for better solderability
4. Verify all design rules before submission

Pro Tip: You can access my complete design files through the GitHub repository linked at the end of this guide.

Once your PCBs arrive, it's time for assembly. The XTSD chip has a QFN package, which requires careful soldering.

Soldering the XTSD Chip:

1. Apply solder paste to all chip pads using a stencil or careful manual application
2. Use tweezers to precisely place the chip on the pads
3. Heat the board using a hotplate or reflow oven until the solder melts and reflows
4. Allow the board to cool naturally - don't force cool it!

Microscopic Inspection:

After soldering, use a microscope or magnifying glass to check for:

1. Bridging between pins
2. Proper solder fillets
3. Chip alignment

Adding Connectors:

1. Insert SIL pin headers into a breadboard
2. Place the PCB on top, aligning the holes with the pins
3. Solder each pin using a fine-tip soldering iron
4. Use copper braid to clean up any excess solder

Safety Note: Work in a well-ventilated area and use ESD protection when handling the chip.

The XTSD chip uses standard SPI interface, making Arduino integration straightforward.

SPI Connection Diagram:

XTSD04GLGEAG → Arduino Pin

─────────────────────────

CS (Chip Select) → D10

MOSI (Master Out) → D11

MISO (Master In) → D12

SCK (Clock) → D13

VCC (Power) → 3.3V

GND (Ground) → GND

Breadboard Setup:

1. Place the breakout board on your breadboard
2. Connect power lines first (3.3V and GND)
3. Connect the four SPI signals (CS, MOSI, MISO, SCK)
4. Double-check all connections before powering on

Important: The chip requires 3.3V power! Do not connect it to 5V as this will damage the chip.

Upload the Code:

1. Install the SdFat library via Arduino Library Manager
2. Open the provided Arduino sketch
3. Select your board and port
4. Upload the code to your Arduino

Serial Interface Test:

1. Open Serial Monitor at 9600 baud
2. You should see the main menu with 8 options
3. Test each function:
4. List files (should show any existing files)
5. Create a new text file
6. Write data to the file
7. Read back the data
8. Delete files (with confirmation)
9. View SD card information

Cross-Platform Testing:

1. Remove the board from Arduino
2. Insert it into a computer's SD card reader
3. Verify the computer recognizes it as a standard SD card
4. Check that files created via Arduino are accessible
5. Try copying files from your computer to the chip