MSP430F5529 SD Card interface with FATFS

Other Parts Discussed in Thread: MSP430F5529

Hello,

I am trying to interface my MSP430 Launchpad with an external SD Card for my senior design project. I was able to establish communication using Elm-Chan's FatFS module. The two main questions/problems I have is:

1. When I try using the FatFS mount method to unmount the work area, I try setting the work area to null and I get an error that identifier "null" is unidentified. I'm having trouble believing that null isn't defined. Does this mean that I have to set the work area to 0 to unmount?

2. Even in the data I have, it is set in a particular format. For example, from the original code I found, the data in the text file on the card was as follows: data (directory) (file name). I would like to know if it would be possible if I only write data to the card.  I am attaching my main file for reference

/*
 * SD_main.c
 *
 *  Created on: Jan 9, 2016
 *      Author: rajur
 */
/*The following code is a stripped down version of a previous project, there
 * may be parts of this code that are unnecessary. This example will create
 * text file and write a few letters. If you have any questions or would like
 * to learn more how to implement this project using more extensive commands
 * please contact me at OCB456@aol.com. Thanks!
 * */

#include <MSP430F5529.h>
#include "ff.h"
#include "diskio.h"

void initCLK(void);
void SetVcoreUp (unsigned int level);
FRESULT WriteFile(char*, char*, WORD);
void fat_init(void);

FIL file;                                               /* Opened file object */
FATFS fatfs;                                            /* File system object */
DIRS dir;                                               /* Directory object   */
DIRS dir2;
FRESULT errCode;                                        /* Error code object  */
FRESULT res;                                            /* Result object      */
UINT bytesRead;                                         /* Bytes read object  */
UINT read;                                              /* Read bytes object  */


FATFS test_for_new; // to check if a new file can be written
FIL test_file;

unsigned char MST_Data,SLV_Data;
BYTE buffer[32];
int result=1;

void main(void){

    WDTCTL = WDTPW+WDTHOLD;                     // Stop watchdog timer

    initCLK();

    __enable_interrupt();



    fat_init();                                 //mount, set directory to read from, assign file
    unsigned int bytesWritten;
    f_write(&file, "abcdefg \r\n", 32, &bytesWritten);
    f_write(&file, "ok", 32, &bytesWritten);
    f_close(&file);
//    f_closedir(&dir);
    f_mount(0,null);


   /* f_mount(0,&test_for_new); // f_mount(0,0);
    //new
    f_open(&test_file, "test_file.txt", FA_CREATE_NEW);
    f_write(&test_file, "Hi Mom", 32, &bytesWritten);
    f_close(&test_file);//new*/
 //   f_closedir(&dir2);
  //  f_mount(0,&test_for_new);
    while(1);
}

void fat_init(void){
    errCode = -1;

    while (errCode != FR_OK){                               //go until f_open returns FR_OK (function successful)
        errCode = f_mount(0, &fatfs);                       //mount drive number 0
        errCode = f_opendir(&dir, "/");				    	//root directory

        errCode = f_open(&file, "TESTE.txt", FA_CREATE_ALWAYS | FA_WRITE);
        if(errCode != FR_OK)
            result=0;                                       //used as a debugging flag
    }
}


void initCLK(void){
  volatile unsigned int i;

  // Increase Vcore setting to level3 to support fsystem=25MHz
  // NOTE: Change core voltage one level at a time..
  SetVcoreUp (0x01);
  SetVcoreUp (0x02);
  SetVcoreUp (0x03);

  UCSCTL3 = SELREF_2;                       // Set DCO FLL reference = REFO
  UCSCTL4 |= SELA_2;                        // Set ACLK = REFO

  __bis_SR_register(SCG0);                  // Disable the FLL control loop
  UCSCTL0 = 0x0000;                         // Set lowest possible DCOx, MODx
  UCSCTL1 = DCORSEL_7;                      // Select DCO range 50MHz operation
  UCSCTL2 = FLLD_1 + 762;                   // Set DCO Multiplier for 25MHz
                                            // (N + 1) * FLLRef = Fdco
                                            // (762 + 1) * 32768 = 25MHz
                                            // Set FLL Div = fDCOCLK/2
  __bic_SR_register(SCG0);                  // Enable the FLL control loop

  // Worst-case settling time for the DCO when the DCO range bits have been
  // changed is n x 32 x 32 x f_MCLK / f_FLL_reference. See UCS chapter in 5xx
  // UG for optimization.
  // 32 x 32 x 25 MHz / 32,768 Hz ~ 780k MCLK cycles for DCO to settle
  __delay_cycles(782000);

  // Loop until XT1,XT2 & DCO stabilizes - In this case only DCO has to stabilize
  do
  {
    UCSCTL7 &= ~(XT2OFFG + XT1LFOFFG + DCOFFG);
                                            // Clear XT2,XT1,DCO fault flags
    SFRIFG1 &= ~OFIFG;                      // Clear fault flags
  }while (SFRIFG1&OFIFG);                   // Test oscillator fault flag
}

void SetVcoreUp (unsigned int level)
{
  // Open PMM registers for write
  PMMCTL0_H = PMMPW_H;
  // Set SVS/SVM high side new level
  SVSMHCTL = SVSHE + SVSHRVL0 * level + SVMHE + SVSMHRRL0 * level;
  // Set SVM low side to new level
  SVSMLCTL = SVSLE + SVMLE + SVSMLRRL0 * level;
  // Wait till SVM is settled
  while ((PMMIFG & SVSMLDLYIFG) == 0);
  // Clear already set flags
  PMMIFG &= ~(SVMLVLRIFG + SVMLIFG);
  // Set VCore to new level
  PMMCTL0_L = PMMCOREV0 * level;
  // Wait till new level reached
  if ((PMMIFG & SVMLIFG))
    while ((PMMIFG & SVMLVLRIFG) == 0);
  // Set SVS/SVM low side to new level
  SVSMLCTL = SVSLE + SVSLRVL0 * level + SVMLE + SVSMLRRL0 * level;
  // Lock PMM registers for write access
  PMMCTL0_H = 0x00;
}

Thanks,

Ravi Raju