SLVUDI2 September   2025

 

  1.   1
  2.   Description
  3.   Get Started
  4.   Features
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  7. 2Hardware
    1. 2.1 Board Overview
    2. 2.2 Key Features
      1. 2.2.1 Processor
      2. 2.2.2 Memory and Storage
      3. 2.2.3 Interface and Peripherals
      4. 2.2.4 Expansion Connectors and Expansion Headers to Support Application-Specific Capes
    3. 2.3 Power Requirements
      1. 2.3.1 Integrated Power Architecture
      2. 2.3.2 Advanced Power Management Features
    4. 2.4 Header Information
      1. 2.4.1 Cape Expansion Headers
      2. 2.4.2 65 Possible Digital I/Os
      3. 2.4.3 PWMs and Timers
      4. 2.4.4 Analog Inputs
      5. 2.4.5 UART
      6. 2.4.6 I2C
      7. 2.4.7 SPI
    5. 2.5 Detailed Hardware Design
      1. 2.5.1 USB Interface
        1. 2.5.1.1 USB 2.0 Type-A Interface
        2. 2.5.1.2 USB 2.0 Type-C® Interface
      2. 2.5.2 Ethernet Interface
      3. 2.5.3 Power Supply Interface
      4. 2.5.4 DDR3L SDRAM Interface
      5. 2.5.5 eMMC Flash Interface
      6. 2.5.6 Micro SD Card Slot Interface
      7. 2.5.7 Grove Connector Interfaces
        1. 2.5.7.1 Grove I2C Interface (J4)
        2. 2.5.7.2 Grove UART Interface (J5)
  8. 3Hardware Design Files
    1. 3.1 Schematics, PCB Layout and BOM
  9. 4Compliance Information
    1. 4.1 Compliance – FCC Requirement
  10. 5Additional Information
    1. 5.1 Known Hardware or Software Issues
    2. 5.2 Trademarks
    3. 5.3 Brand Uses Approval
  11. 6Related Documentation

2.5.6 Micro SD Card Slot Interface

BeagleBone Green Eco includes a standard microSD card slot (P10), providing users with expandable storage options and an alternative boot source. The card slot supports SD and SDHC cards up to 32GB, with SDXC cards also compatible when appropriately formatted.

The microSD interface connects to the AM335x processor through the MMC0 controller, utilizing a 4-bit data bus (SD_DAT0 through SD_DAT3) that allows for transfer rates up to 24MB/s. The interface includes command (SD_CMD) and clock (SD_CLK) lines required for SD protocol communication, with series resistors to maintain signal integrity.

A card detect switch (SD_CD) allows the system to sense when a card is inserted or removed, enabling hot-plug functionality. This detection mechanism permits the operating system to automatically mount or safely unmount the SD card when physical changes occur.

The SD card interface is powered by the 3.3V rail. Pullup resistors on the data and command lines maintain proper signal levels according to the SD card specification.

For embedded applications, the microSD slot provides several key advantages:

  • Alternative boot source when the onboard eMMC needs reprogramming
  • Easy data exchange between the BeagleBone.org and other systems
  • Storage expansion for applications requiring additional space
  • System recovery option in case of software corruption on the primary eMMC

To boot from the microSD card rather than the onboard eMMC, users can press the BOOT button while applying power to the board, which forces the AM335x processor to prioritize the SD card in the boot sequence.

BEAGL-BONE-GRN-ECO microSD Card Slot Interface Block Diagram Figure 2-9 microSD Card Slot Interface Block Diagram