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EEPROM Read/Write AT89C51AC3

Tri Jatmiko

Hello,

I have the following code for writing/reading EEPROM of this device.

unsigned char eepromWrite (const unsigned int Address, unsigned char Data) {
    bit oldEA;
    unsigned char DataReadBack;

    if (Address <= 0x07ff)
    {
        oldEA = EA;
        EA = 0;

        EECON |= 0x02; // Enable EEPROM memory space
        XBYTE[Address] = Data;
        EECON &= 0xFD; // Disable EEPROM memory space
        EA = oldEA;

        EECON = 0x50; EECON = 0xA0;     // Programming...

        // wait programming...
        while(EECON & b00000001);

        // Byte re-read
        oldEA = EA;
        EA = 0;
        EECON |= 0x02; // Enable EEPROM memory space
        DataReadBack = XBYTE[Address];
        EECON &= 0xFD; // Disable EEPROM memory space
        EA = oldEA;
        if (DataReadBack != Data)
        {
            return(2);
        }
        return(0);
    }
    else
    {
        return(1);
    }
}

unsigned char eepromRead (const unsigned int Address, unsigned char* Data) {
bit oldEA;
	if (Address <= 0x07ff) {
	    oldEA = EA;
	    EA = 0;
		while(EECON & b00000001); //EEbusy
	    EECON |= 0x02; // Enable EEPROM memory space
	    *Data = XBYTE[Address];
	    EECON &= 0xFD; // Disable EEPROM memory space
	    EA = oldEA;
		return (0);
	}
    else
    {
        *Data = 0;
        return(1);
    }
}

Then I write the following code for write/read multiple byte (or structure)

void write_to_EEPROM (unsigned int EEPROM_address, void *buffer, unsigned char buffer_len) {
unsigned char *bp;
for (bp = buffer; buffer_len; buffer_len--, bp++, EEPROM_address++)
  {
	eepromWrite(EEPROM_address, *bp);
  }
  Wait20ms();
}

void read_from_EEPROM (unsigned int EEPROM_address, void *buffer, unsigned char buffer_len) {
unsigned char *bp;

for (bp=buffer; buffer_len; buffer_len--, bp++, EEPROM_address++)
  {
	eepromRead(EEPROM_address, bp);
  }
}

Most of the time it works. For example I could write/read a struct:
typedef struct    {
                     uchar       MotorMin;
		     uchar       MotorKnee;
                     uchar       MotorMax;
                  }  Blower_TYP;

//////////

write_to_EEPROM (FAN_ADDR, &BlowerNew, sizeof (Blower_TYP));

void readMotorConf (void) {
 Blower_TYP temp;
 read_from_EEPROM(FAN_ADDR, &temp, sizeof(Blower_TYP));
 Blower = temp;
}
}


Only sometime the read function give wrong reading of the blower. What could be the problem on above code? Thanks for advise!

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