SD Card Libary¶

Key Features¶

• Read and write data operations on SD cards using either the SPI interface or native 4bit interface
• Port of FatFS - FAT file system module R0.09 (C)ChaN, 2011 (http://elm-chan.org/fsw/ff/00index_e.html).
• Beware: FAT with long file names may be covered by various patents (in particular those held by Microsoft). Use of this code may require licensing from the patent holders
• Beware: 4bit SD protocol is subject to petents of the SD Association. When enabled on commercial products a license may be required. (see: https://www.sdcard.org/developers/howto/ )
• Benchmark with 4bit interface multiblock read speed is about 4MBytes/sec. 1.2MBytes/sec with SPI.

To Do¶

• Initialization at low clock speed (400KHz max) for the 4bit interface.
• Test with SDXC card, SD physical layer ver 1.0 compliant card and MMC card (currently supported only with SPI interface).
• support for MMC/eMMC at 4 and 8bit bus.
• Date/Time function for files timestamp returning real date/time.

Firmware Overview¶

This module provides functions to initialize SD cards, read and write data. To enable the 4bit SD native bus interface functions it is necessary to uncomment the “//#define BUS_MODE_4BIT” in the “module_FatFs/src/diskio.h”. Resources (ports and clock blocks) used for the interface need to be specified in either “module_sdcardSPI/SDCardHostSPI.xc” or “module_sdcard4bit/SDCardHost4bit.xc” in the initialization of the SDif structure.

Known Issues¶

• Initialization for the 4bit protocol not done at correct clock speed of 400KHz maximum.

Required Repositories¶

• xcommon git@github.com:xcore/xcommon.git

Support¶

Issues may be submitted via the Issues tab in this github repo. Response to any issues submitted are at the discretion of the maintainers of this component.