[SOLVED] Error reading from EEPROM

[Raady Here]

dsPIC30F5011
24LC256(EEPROM)
MPLAB V8.8

Hi ,

I have written to read and write from EEPROM.
But when I am writing and integer to it I am not able to read it back exactly !
Help Required !

char HLVLineBuf[20];
static unsigned char *ptr;
unsigned int temp_HV = 0, temp_LV = 0;
unsigned int Voltage_Low,Voltage_High;
....
ptr = HLVLineBuf;
....
    temp_HV =  ConvertSTRING_Int(&HLVLineBuf[0],3);
    temp_LV =  ConvertSTRING_Int(&HLVLineBuf[3],3);
    printf("\n\rtemp_HV_CUT = %d", temp_HV);
    printf("\n\rtemp_LV_CUT = %d", temp_LV);
    Voltage_High = temp_HV;
    Voltage_Low  = temp_LV;
    ptr = (unsigned char*)&Voltage_High;
    Write_String_EEPROMx(2, ptr, EE_CUTOFF_HIGH);				// write default high voltage cutoff value
    ptr = (unsigned char*)&Voltage_Low ; 
    Write_String_EEPROMx(2, ptr, EE_CUTOFF_LOW);				// write default low voltage cutoff value
				
    Read_String_EEPROMx(2,ptr,EE_CUTOFF_HIGH);
    printf("\n EE_HV_CUT = %s", ptr);
    Read_String_EEPROMx(2,ptr,EE_CUTOFF_LOW);
    printf("\n EE_LV_CUT = %s", ptr);

void Write_String_EEPROMx(unsigned char length, unsigned char *arr,unsigned int Address)
{
	EEPROM_WP_Disable;
	WaitI2C(10000);							// Inital delay
	add.value = Address;
	IdleI2C();
	StartI2C();
	IdleI2C();
	MasterWriteI2C(EEPROM_WRITE_ID);                    // Write Control byte
	IdleI2C();
    while(I2CSTATbits.ACKSTAT);
	MasterWriteI2C(add.msb);				// Write MSB Address
   	IdleI2C();
    while(I2CSTATbits.ACKSTAT);
	MasterWriteI2C(add.lsb);				// Write LSB Address
	IdleI2C();
    while(I2CSTATbits.ACKSTAT);
    while(length--)
	{
		MasterWriteI2C(*arr++);       		// Write data byte
		IdleI2C();
	    while(I2CSTATbits.ACKSTAT);
	}			    						// Write String
    while(I2CSTATbits.ACKSTAT);
	StopI2C();
	IdleI2C();
	EEPROM_WP_Enable;
}


unsigned char Read_String_EEPROMx(unsigned int length, unsigned char *arr, unsigned int Address)
{
	
	if(length > 64)
		return 0;	
	WaitI2C(10000);							// bus free time 4.7 ms is required for every new transmission
	add.value = Address;
	IdleI2C();
	StartI2C();
	IdleI2C();
	MasterWriteI2C(EEPROM_WRITE_ID);       	// Write Control byte
	IdleI2C();
	MasterWriteI2C(add.msb);				// Write MSB Address
   	IdleI2C();
	MasterWriteI2C(add.lsb);				// Write LSB Address
	IdleI2C();
	RestartI2C();
   	IdleI2C();
	MasterWriteI2C(EEPROM_READ_ID);       	// Read Control byte
	IdleI2C();
   	while(length > 1 )
   	{
	    *arr++ = MasterReadI2C();
		IdleI2C();
    	Nop();
		AckI2C();
		IdleI2C();
		length--;
		*arr = '\0';
	}	
    *arr++ = MasterReadI2C();
    *arr = '\0'; 
	IdleI2C();
	NotAckI2C();
	IdleI2C();
	StopI2C();
	IdleI2C();
	return 1;

}	

unsigned int ConvertSTRING_Int(unsigned char *ptr, unsigned char noofbytes)
{
	unsigned int c = 0,i = 1;
	while(--noofbytes)
		i = i*10;
	while(*ptr)
	{
		c = c + i*(*ptr++ - 48);
		i = i/10;
	}
	return c;
}

I tried to print the string , and I expect that to be 222 and 111 respectively. Once I get the exact one I can convert back to integers.

 

[milind.a.kulkarni]

Couple of thing you need to do -

first of all check your HLVLineBuf contents I think some of them are not integer and when you are doing -48 will give you different value if it is not integer...... If I see your blog also your are counting for first three bytes ..... then I think you need to pass 0 to 2 indexing

Try this in your code to get an idea....

noofbytes1 = noofbytes
while(noofbytes1)
{
		i = i*10;
                noofbytes1 = noofbytes1 -1
}

 

[Raady Here]

They are not integers, it reads values from KEYPAD and its a char , so i m trying to convert to int and then type casting and then storing. but while retrieval I am not able see to the same. where could I have been wrong.

your bit of code is the same loop with an extra variable, if I am not wrong.

 

[jayanth.devarayanadurga]

Try linke this for EEPROM read and write functions.

---

Code C - [expand]
1
Write_String_EEPROMx(2, &ptr, EE_CUTOFF_LOW);

---

Edit: The above is wrong.

This is also incorrect. Voltage_High is 16 bits wide and ptr is a pointer to an unsigned char which is 8 bit wide. You are assigning the address of Voltage_High to ptr after typecasting. ptr contains the address of first byte of Voltage_High.

---

Code C - [expand]
1
ptr = (unsigned char*)&Voltage_High;

---

ptr has to be de-referenced with typecasting while reading from or writing to eeprom location.

 

[kripacharya]

They are not integers, it reads values from KEYPAD and its a char , so i m trying to convert to int and then type casting and then storing. but while retrieval I am not able see to the same. where could I have been wrong.

your bit of code is the same loop with an extra variable, if I am not wrong.

Hey there !!

Your posted code 'snippets' are wayyyy too long for me to decipher.
Could you just pull out the lines where your data of concern is being manipulated ?

It's most likely a problem of type conversion. But lets have a look first.... in a more condensed format.