Interfacing external memory with LPC2148 using I2C Protocol (PART 2)

Dummy write operation

So once your done with writing data into the EEPROM,you would want to read from the location where you have written into.

The diagram above clearly shows the steps how it needs to be done. 

CODE:

#include<lpc214x.h> // standard header file
#include”appdef.h” // defining bits,example:#define BIT0 0x01<<0
#include”armlcd.h” // initialisations for lcd
#define led_port BIT0+BIT1+BIT8+BIT9+BIT25+BIT15+BIT12+BIT28
int c=0;
int r=0,dw=1,ss=0,rs=0,j;
char ch;
__irq void led(void)
{
switch(I2C0STAT)
{
case 0x08 : //lcd(‘s’); // 1.start
                  I2C0CONCLR=BIT3; 
                  I2C0DAT=0xa0; // dummy write
                  break;
case 0x10 :// lcd(‘b’); // 4. repeated start condition status
                   I2C0CONCLR=BIT3+BIT5;
                  I2C0DAT=0xa1; // read
                  break;
case 0x18 : //lcd(‘a’); // 2. write  ack
                   I2C0CONCLR=BIT3+BIT5;
                   I2C0DAT=0x00; // memory address
                   break;
case 0x28 : //lcd(‘k’); // 3. ack
                   I2C0CONCLR=BIT3;
                   I2C0CONSET|=BIT5; // repeated start bit
                   break;
case 0x40 : //lcd(‘r’);  // 5.read ack
                   I2C0CONCLR=BIT3;
                   I2C0CONSET=BIT2; // aa flag
                   break;
case 0x48 : lcd(‘l’);
                   I2C0CONCLR=BIT3;
                   break;
case 0x50 : I2C0CONCLR=BIT3; // 6.start receiving data
                   ch=I2C0DAT;
                   lcd(ch);
                  if(dw==9)
                  {
                       I2C0CONCLR=BIT2;  // sending a no ack after reading 10 bytes
                  }
                  dw++;
                  break;
case 0x58 ://lcd(‘n’);   // 7.stop bit
                   I2C0CONCLR=BIT3;
                   I2C0CONSET=BIT4;
                   break;
default:lcd(‘f’);
             I2C0CONCLR=BIT3;
              break;
}

VICVectAddr=0x00;
}

int main()
{

rs_clr();
en_clr();
lcd_init();
rs_set();
en_clr();
//lcd(‘i’);
PINSEL0=BIT4+BIT6;
VICVectCntl0=0x29;
VICVectAddr0=(unsigned) led;
VICIntEnable=BIT9;

I2C0CONSET=BIT6;
I2C0CONCLR=BIT3;
I2C0SCLH=0x4B;
I2C0SCLL=0x4B;

I2C0CONSET|=BIT5; //start
while(1);
}
void lcd_init()
{
unsigned int i;
PINSEL0 = 0x00000000;

lcd_dir_write(); // output port
for (i=0;i<1000;i++);
lcd(0x33);
lcd(0x32);
lcd(0x28);
lcd(0x0e);
lcd(0x01);
lcd(0x06);
lcd(0x80);

for (i=0;i<1000000;i++);
}

void lcd(unsigned char val)
{
lcd1(val>>4);
lcd1(val);
}

void lcd1(unsigned char c)
{
unsigned int i;
IOCLR0 = 0x00f00000;
IOSET0 = (c<<20); // d4 connected to 20th port pin
en_set();
for (i=0;i<1000000;i++);
en_clr();

}