MMC Card Reader Development

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This wiki describes the development of the MMC Card Reader Project

Contents

Architecture

  • See here for block diagram


Development Roadmap

Phase 1

  • Create stdio.h wrapper for file system in freertos_posix
  • Use existing I2C EEPROM driver for development

Phase 2

  • Circuit design for interfacing MMC

Phase 3

  • SPI driver for MMC

Phase 4

  • Test for normal read/write function
  • hotswap (should not hang or cause voltage dip)
  • multiple file read/write (protection)


Circuit and PCB


Software Implementation

Comparison of FatFs and stdio API

  • selected list is described below
Comparison between FatFs and stdio API
Function stdio.h FatFs Remarks
Open
 FILE * 

fopen (

 const char * filename, 
 const char * mode
 

);

 FRESULT 

f_open (

 FIL* FileObject,       /* Pointer to the blank file object structure */
 const XCHAR* FileName, /* Pointer to the file neme */
 BYTE ModeFlags         /* Mode flags */

);

  • FILE matches FIL
  • filename matches FileName
  • mode matches ModeFlags
  • stdio.h has no equivalent FRESULT
Read 7.73 30
Write 7.85 30
Close 4.62 40
Seek 4.81 40
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