Help me with MSP430G2233 Flash Memory

You should start with code examples for the processor - they can be found here:

This is the example for writing to the info segments in the flash:

//******************************************************************************
//  MSP430G2xx3 Demo - Flash In-System Programming, Copy SegC to SegD
//
//  Description: This program first erases flash seg C, then it increments all
//  values in seg C, then it erases seg D, then copies seg C to seg D.
//  Assumed MCLK 771kHz - 1428kHz.
//  //* Set Breakpoint on NOP in the Mainloop to avoid Stressing Flash *//
//
//               MSP430G2xx3
//            -----------------
//        /|\|              XIN|-
//         | |                 |
//         --|RST          XOUT|-
//           |                 |
//
//  D. Dang
//  Texas Instruments Inc.
//  December 2010
//   Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************

#include <msp430.h>

char  value;                                // 8-bit value to write to segment A

// Function prototypes
void write_SegC (char value);
void copy_C2D (void);

int main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer
  if (CALBC1_1MHZ==0xFF)					// If calibration constant erased
  {											
    while(1);                               // do not load, trap CPU!!	
  }
  DCOCTL = 0;                               // Select lowest DCOx and MODx settings
  BCSCTL1 = CALBC1_1MHZ;                    // Set DCO to 1MHz
  DCOCTL = CALDCO_1MHZ;
  FCTL2 = FWKEY + FSSEL0 + FN1;             // MCLK/3 for Flash Timing Generator
  value = 0;                                // initialize value

  while(1)                                  // Repeat forever
  {
    write_SegC(value++);                    // Write segment C, increment value
    copy_C2D();                             // Copy segment C to D
    __no_operation();                       // SET BREAKPOINT HERE
  }
}

void write_SegC (char value)
{
  char *Flash_ptr;                          // Flash pointer
  unsigned int i;

  Flash_ptr = (char *) 0x1040;              // Initialize Flash pointer
  FCTL1 = FWKEY + ERASE;                    // Set Erase bit
  FCTL3 = FWKEY;                            // Clear Lock bit
  *Flash_ptr = 0;                           // Dummy write to erase Flash segment

  FCTL1 = FWKEY + WRT;                      // Set WRT bit for write operation

  for (i=0; i<64; i++)
  {
    *Flash_ptr++ = value;                   // Write value to flash
  }

  FCTL1 = FWKEY;                            // Clear WRT bit
  FCTL3 = FWKEY + LOCK;                     // Set LOCK bit
}

void copy_C2D (void)
{
  char *Flash_ptrC;                         // Segment C pointer
  char *Flash_ptrD;                         // Segment D pointer
  unsigned int i;

  Flash_ptrC = (char *) 0x1040;             // Initialize Flash segment C pointer
  Flash_ptrD = (char *) 0x1000;             // Initialize Flash segment D pointer
  FCTL1 = FWKEY + ERASE;                    // Set Erase bit
  FCTL3 = FWKEY;                            // Clear Lock bit
  *Flash_ptrD = 0;                          // Dummy write to erase Flash segment D
  FCTL1 = FWKEY + WRT;                      // Set WRT bit for write operation

  for (i=0; i<64; i++)
  {
    *Flash_ptrD++ = *Flash_ptrC++;          // copy value segment C to segment D
  }

  FCTL1 = FWKEY;                            // Clear WRT bit
  FCTL3 = FWKEY + LOCK;                     // Set LOCK bit
}

Try to understand that and then build your own code based on this.

I conplied with other codes.  Seem like i need to clear up or reorganize code so it won't use up much of memory.  Or is there another way can solve?  Thanks for you reply

I just reduced some code. Should be fine now. Thank you
however, it is not everytime will write into flash. here is my code.

one question, why do we need to loop 64 times to copy the flash?

void flash_write_low(int fLow)
{
_DINT(); // Disable interrupts(IAR workbench).
FCTL2 = FWKEY + FSSEL_1 + FN0; // Clk = SMCLK/4
FCTL1 = FWKEY + ERASE; // Set Erase bit
FCTL3 = FWKEY; // Clear Lock bit
*FlashLow = 0; //Clear Flash
FCTL1 = FWKEY + WRT; // Set WRT bit for write operation
*FlashLow = fLow; // copy value to flash

FCTL1 = FWKEY; // Clear WRT bit
FCTL3 = FWKEY + LOCK; // Set LOCK bit
_EINT();
}

Please advice. Thank you!