Example Summary

Example to read and write data onto an SD Card.

Peripherals & Pin Assignments

When this project is built, the SysConfig tool will generate the TI-Driver configurations into the ti_drivers_config.c and ti_drivers_config.h files. Information on pins and resources used is present in both generated files. Additionally, the System Configuration file (*.syscfg) present in the project may be opened with SysConfig’s graphical user interface to determine pins and resources used.

• CONFIG_GPIO_LED_0 - Indicates the driver was initialized within mainThread()
• CONFIG_SDFatFS_0 - Connection to SD card

BoosterPacks, Board Resources & Jumper Settings

This example requires a BOOSTXL-SHARP128 LCD & SD Card BoosterPack.

For board specific jumper settings, resources and BoosterPack modifications, refer to the Board.html file.

If you’re using an IDE such as Code Composer Studio (CCS) or IAR, please refer to Board.html in your project directory for resources used and board-specific jumper settings.

The Board.html can also be found in your SDK installation:

    <SDK_INSTALL_DIR>/source/ti/boards/<BOARD>

Example Usage

• Example output is generated through use of Display driver APIs. Refer to the Display driver documentation found in the SimpleLink MCU SDK User’s Guide.

• The SD card must be formatted for the FAT filesystem prior to running the example. Errors will occur otherwise.

• 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. CONFIG_GPIO_LED_0 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 TI-RTOS or FreeRTOS synchronization. Also included is an implementation of the “device I/O” model for the TI compiler C runtime support (RTS) library. This provides transparent support for using the C stdio.h library functions (fopen, fread, fwrite, etc…) instead of the raw, project-specific, API functions provided by FatFs (f_open, f_write).

• 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. Refer to the FatFS documentation for more information.

This application uses one thread:

mainThread performs the following actions:

1. Creates and initializes SDFatFS 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 SDFatFS 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.

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