README

Example Summary

Example to read and write data onto a SD Card (SPI interface)

Peripherals Exercised

• Board_GPIO_LED0 - Indicates that the board was initialized within mainThread()

• Board_SDSPI0 - Connection to SD card

Resources & Jumper Settings

If you’re using an IDE (such as CCS or IAR), please refer to Board.html in your project directory for resources used and board-specific jumper settings. Otherwise, you can find Board.html in the directory <SDK_INSTALL_DIR>/source/ti/boards/<BOARD>.

This example requires an external SD Card boosterpack.

Example Usage

• Open a serial session (e.g. PuTTY, etc.) to the appropriate COM port. *The COM port can be determined via Device Manager in Windows or via ls /dev/tty* in Linux.

The connection will have the following settings:

    Baud-rate:     115200
    Data bits:          8
    Stop bits:          1
    Parity:          None
    Flow Control:    None

• Run the example. Board_GPIO_LED0 turns ON to indicate driver initialization is complete.

• The example proceeds to read the SD card. If an input.txt file is not found, the file is created on the SD card with the following text:

  
  "***********************************************************************\n"
  "0         1         2         3         4         5         6         7\n"
  "01234567890123456789012345678901234567890123456789012345678901234567890\n"
  "This is some text to be inserted into the inputfile if there isn't     \n"
  "already an existing file located on the SDCard.                        \n"
  "If an inputfile already exists, or if the file was already once        \n"
  "generated, then the inputfile will NOT be modified.                    \n"
  "***********************************************************************\n"

• The input.txt file is then read and it’s contents are written to a new file called output.txt. If the file already exists on the SD card, it will be overwritten.

• The contents of the output.txt file are then written to the console.

Application Design Details

• The FatFs source is included and pre-built, together with support for SYS/BIOS or FreeRTOS synchronization. The raw, project-specific, API functions provided by FatFs (f_open, f_write) are used within this example.

• This application demonstrates how to use the SD Card driver to read and write data onto a SD Card using FatFS API calls (f_open, f_read, f_write, etc).

• Users also have the option of writing to a RAM disk using either the CIO runtime system calls or raw FatFS API’s. See the initial setup below to initialize the RAM disk prior to making any CIO or FatFS calls.

    #include <third_party/fatfs/ff.h>
    #include <third_party/fatfs/ffcio.h>
    #include <third_party/fatfs/diskio.h>

    unsigned int ramdiskData[RAMDISKSIZE];
    DRESULT result;

    result = ramdisk_start(ramdiskDriveId, ramdiskData, RAMDISKSIZE, 0);

    if (result != RES_OK) {
        /* ramdisk_start failed */
        while (1);
    }

If using both the RAM disk and SD card filesystems, separate drive ID’s must be used.

This application uses one thread:

mainThread performs the following actions:

1. Creates and initializes SDSPI driver object.

2. Prints the disk size and the amount of free space on it.

3. Open the input.txt file. If not found, create the file for reading and writing. Write the default message to the file.

4. Open the output.txt file. Content will be overwritten if found.

5. Copy the contents of input.txt to output.txt. Closes both files afterwards.

6. Open output.txt, read the file, print the contents to the display, and close output.txt.

7. Again, print the disk size and the amount of free space on it. If the disk was empty, the difference in free space can be observed.

8. Close the SDSPI driver and terminate the example.

TI-RTOS:

• The timespec structure must be initialized with the current UNIX seconds count in order to write files with accurate timestamps. This is due to the fact that the BIOS Seconds module rather than the RTS library time() function is used.

• When building in Code Composer Studio, the configuration project will be imported along with the example. The configuration project is referenced by the example, so it will be built first. These projects can be found under <SDK_INSTALL_DIR>/kernel/tirtos/builds/<BOARD>/(release|debug)/(ccs|gcc).

FreeRTOS:

• The compiler specific RTS library functions for time() and localtime() are used. It is not necessary to initialize the timespec structure.

• Please view the FreeRTOSConfig.h header file for example configuration information.

References

• The FatFS libraries in this example are configured for use without Long File Name (VFAT) or XFAT support. If you chose to reconfigure and build FatFS to include these features, you may be required to license the appropriate patents from Microsoft. For more information, please refer to: http://elm-chan.org/fsw/ff/en/appnote.html#lfn
  • The FatFs project homepage: http://elm-chan.org/fsw/ff/00index_e.html