write and read from eeprom using c (mplab ide)

[ese2709]

hi,

how can i read and write data into eeprom pic16f876a?

someone can help me?

 

[Ian Rogers]

Use this routine

unsigned char ReadEeprom(unsigned int badd )
	{
	EEADR = (badd & 0x0ff);
  	CFGS = 0;
	EEPGD = 0;
	RD = 1;
	return ( EEDATA );              // return with read byte
	}

void WriteEeprom( unsigned int badd,unsigned char bdata )
	{
	EEADR = (badd & 0x0ff);
  	EEDATA = bdata;
  	EEPGD = 0;
	CFGS = 0;
	WREN = 1;
	GIE = 0;  // if used remember re-enable, interrupts cannot be on
	0x55;
	0xAA;
	WR = 1;
	while(WR);
	//GIE = 1;  // if used remember re-enable
	WREN = 0;
	}

This writes / reads into internal eeprom

 

[ese2709]

{	
		delay(10000);

		while(location_enter==0)			//loop until location_enter flag is set
		{
		lcd_goto(0);						//set the lcd cursor to location 0		
		send_string("Choose User     ");	//display string
		lcd_goto(20);						//set the lcd cursor to location 20
		send_string("User ");				//display string
		lcd_goto(25);						//set the lcd cursor to location 25
		send_char(0x30 + location);			//display character (numerical digit which started from 0x30 or zero)
		if(!But1)							//if SW1 is pressed
			{	
				while(!But1);				//waiting for release
				if (location<5)				//if location is not reaching 5
				location++;					//increment by 1
				else
				location=1;					//reset back to 1
			}
		else if(!But2)						//if SW2 is pressed
		{		
			while(!But2);					//wait for release
			if (location>1)					//if location is not reaching 1
			location--;						//decrement by 1
			else
			location=5;						//reset back to 5			
		}
		else if(!But3)						//if SW3/Confirm is pressed
			{
				while(!But3);
				mem = 0x10 + location;				//waiting for release
				store_eeprom(mem,location); [B]//<<<<--------- this one,[/B]
				AddNew(location);			//function call for add new fingerprint into database at desired location
			}
		}
	}

void view_user(void)
{
	lcd_clr();						//clear lcd
	lcd_goto(0);     				//set the lcd cursor to location 0
	mem = 0x10;
	send_string("User 1 2 3 4 5 ");	//display string
	lcd_goto(24);					//set the lcd cursor to location 20
	unsigned char x;
	mem = 0x10;  [B]//<<<<----- memory location[/B]
	for(x=1; x<6; x++)		//loop 5 times for 5 days
	{	send_char(0x20);	//display " "
		mem = mem ++;
		TEMP=get_eeprom(mem);	//retrieve marking[B] <<<---- will read the eeprom[/B]
		send_char(TEMP);	//display marking
	}
	delay(500000);
	lcd_clr();			
}

//store data into specified location in EEPROM
void store_eeprom(unsigned char location,unsigned char data)
{
	EEPROM_WRITE(location,data);		//write data 
	while(WR)							//wait until it finish
	continue;
}

//access EEPROM to retrieve data
unsigned char get_eeprom(unsigned char mem)
{
	unsigned char value;
	value= EEPROM_READ(mem);		//read eeprom and assign the data to variable 
	return value;						//return data
}

can u check it... i`m not really know about c

 

[ese2709]

its ok now... i have done it.... i use 0x0ff ... thank you ian