MicroSD Card SPI / SDIO Castellated Breakout Board

What is it?

Add high-capacity removable storage to your next embedded project with this compact MicroSD Card Breakout Board. Designed with castellated edge pads, the board can be easily soldered directly onto your PCB as a surface-mount module or used with standard headers for breadboard prototyping.

Unlike many MicroSD breakouts that only expose the SPI interface, this board provides access to both SPI and SDIO signals, allowing you to choose the interface that best fits your application. Use SPI for broad compatibility with virtually any microcontroller, or take advantage of SDIO for significantly higher data transfer speeds on supported devices such as STM32, ESP32, RP2040, and other modern MCUs.

Whether you're logging sensor data, storing images, playing audio, or streaming files, this breakout offers a clean and reliable way to integrate MicroSD storage into space-constrained designs.

Features:

• Supports both SPI and SDIO communication interfaces
• Compact footprint with castellated edge pads for direct PCB soldering
• Can also be used with standard pin headers for prototyping
• Ideal for embedded products, prototypes, and production designs
• Clearly labeled pinout for straightforward integration

The breakout board has the following pinouts:

• 3V3
• CLK
• D0 (DATA 0) / MISO
• D1 (DATA 1)
• D2 (DATA 2)
• CD (DATA 3)
• CMD / MOSI
• DET
• GND

It can be used with open source Arduino Libraries such as: SD Library for Arduino

Typical Applications:

• Data logging
• Audio playback and recording
• Image and graphics storage
• Firmware updates and file management
• IoT edge devices
• Portable instruments
• Robotics and automation
• DIY electronics and maker projects

Why Castellated?

Castellated modules provide a professional, low-profile solution for integrating reusable circuitry into your own PCB. Simply place the module onto matching PCB footprints and solder along the edges—no bulky headers required. This makes the breakout equally suitable for rapid prototyping and permanent product integration.

Whether you need the simplicity of SPI or the performance of SDIO, this breakout board gives you the flexibility to support both from a single compact module.