SD Card - Long File Name Support, PreScaler Formula

Hello Sukru,

For a PSCDIV of n, the formula is going to be 2⁽ⁿ⁺¹⁾ .

As far as extended filenames are concerned, let me look into this a bit and I will follow up.

Thanks, Micheal.

Michael,

Could you test  2⁽ⁿ⁺¹⁾  on your machine. I checked Timer0 with the values below. Basically I am counting the number of intterupts in the isr. The board is set up at 12288000 Hz. Timer period is set to 5DC000 h = 6144000, which is half of the system clock. So it should correspond to 1 s. but I get 30 seconds of run instead of 60s. The formula, according to the experiments here, should be 2ⁿ .

*CPU_TIM0_CTRL = 0x8002;

*CPU_TIM0_PLWR = 0xC000;

*CPU_TIM0_PHWR = 0x005D;

Timer1_Start();

while(1)

            if(Timer1_InterruptCounter == 60)

                      break;

Timer1_Stop();

printf("Timer1 Interrupt Counter = %d\n", Timer1_InterruptCounter);

ATA_fopen can very easily be modified to use long filenames. Here is an excerpt of the relevant section in my code :

    ata_error = ATA_findFirst(pAtaFile);

    // find the file, if it exists
    do
    {
        // get the file name for this entry
        ata_error = ATA_getLongName(pAtaFile, FileName, 0, 255);

        // file name is the same? (and file is not deleted)
        if ((strncmp(FileName, name, 255) == 0) && pAtaFile->Filename[0] != 0xE5)
            return ata_error; // We have a match

HTH,

- Thomas

I tried that but it did not work.

Maybe if you change some lines in your code then it will work...

Seriously though, you really need to provide more information / insight into what is happening if you want us to be able to help you. Try running the code step-by-step to see what is happening.

Yes, it may work. I think TI engineers should do this job for the sake of the completeness of the API.

Sukru

Hello All,

This solution probably will find an already created file.

But I would like to create a such file (with long file name). I have tried ATA_setLongFileName() and ATA_createLong() but the program stuck and after SD card  is no more detected as formated in my computer.

Can you help - how to create file with long file name?

Regards,

Markov

Hi Marcho,

Indeed, setLongFileName and createLong are the right functions in this case. See my code below which I have been using successfully for some time :

AtaError ATA_fopen(AtaFile *pAtaFile, const char *name, int create)
{
    char FileName[256];
    AtaError ata_error;

    ata_error = ATA_ERROR_NONE;

    // find the first file in this drive
    ata_error = ATA_fileInit(gpstrAtaDrive, pAtaFile);

    /* Set the temp write buffer */
    pAtaFile->pDrive->_AtaWriteBuffer = AtaWrBuf;

    ata_error = ATA_findFirst(pAtaFile);

    // find the file, if it exists
    do
    {
        // get the file name for this entry
        ata_error = ATA_getLongName(pAtaFile, FileName, 0, 255);

        // file name is the same? (and file is not deleted)
        if ((strncmp(FileName, name, 255) == 0) && pAtaFile->Filename[0] != 0xE5)
            return ata_error; // We have a match

        // if the file name is not the same, get the next entry
        ata_error = ATA_findNext(pAtaFile);
        // have we get the empty entry?
        if(ata_error==ATA_ERROR_FILE_NOT_FOUND)
        {
            break;
        }
    } while (1);

    // if the file does not exist, then create it using the empty entry and return the file descriptor
    if (ata_error==ATA_ERROR_FILE_NOT_FOUND && create)
    {
        // set the file name and extension name
        ata_error = ATA_setLongFileName(pAtaFile, (char*)name);

        /* Create a file, returns 0 for successful creation*/
        ata_error |= ATA_createLong(pAtaFile, (char*)name);
    }

    return ata_error;
}

The 'create' argument can be 1 to force creation, or 0 to return FILENOTFOUND error.

HTH,

- Thomas

EDIT: TI really need to add <code> tags to this editor...

Hello Thomas,

Thank you! This variant works! 

Thanks again!

Regards,

Marcho

How do you open a file in read mode? The fopen() in atafs_ext_func() creates a file.

Sukru,

The fopen() variant that I posted above will open a file in read mode, provided that file exists. So will the original one in the atafs example, IIRC.

Note that in my version, the filename is case-sensitive. If you need a case-insensitive one, you will have to modify the strncmp() call with your own, case-insensitive version of the function.

Regards,

- Thomas

Thanks, Thomas.  I will try.