Need Help with I2C!!!

[hemnath]

I'm reading the 16 bit ADC value and displaying in LCD using MCP3421. When i use inbuilt I2C functions in CCS, everything works good. But I'm trying to use the registers and displaying the value. Below program shows how i configured. But in the display, it shows different value what i expect. Please help

#include "18F2520.h"
#include "f2520_regs.h"
#fuses INTRC
#use delay(clock=4000000)

#define RS PIN_A2
#define EN PIN_A1

void lcd_init();
void lcd_cmd(unsigned char);
void lcd_data(unsigned char);

/********** I2C functions**********/
void I2C_INIT();
void I2C_IDLE();
void I2C_START();
void I2C_RESTART();
void I2C_STOP();

unsigned char READ_ADC();
unsigned int16 high_data, low_data, final_data, value,byte2; 

/*****************************************************************
						Main Function
*****************************************************************/
void main()
{
lcd_init();
I2C_INIT();

printf(lcd_data,"switzer");
lcd_cmd(0x01);
delay_ms(1000);
while(1)
{
value = READ_ADC();
lcd_cmd(0x80);
printf(lcd_data,"%lu",value);
delay_ms(200);
}
}


/**********************************************************************
						I2C Initialization
**********************************************************************/
void I2C_INIT()
{
TRIS_C3 = 1;		//	configures SCL and SDA pins as inputs
TRIS_C4 = 1;

SSPCON1	=	0x38;	//	Set I2C master mode
SSPCON2	=	0x00;	

SSPADD	=	10;		//	100Khz at 4Mhz clock

CKE	=	0;			//	Disable SMBus specific inputs
SMP	=	1;			//	Slew rate control disabled 
}

void I2C_IDLE()
{
while((SSPCON2 & 0x1F) | R_W);	//	wait for idle and not writing
}

void I2C_START()
{
I2C_IDLE();
SEN	=	1;
}

void I2C_RESTART()
{
I2C_IDLE();
RSEN	=	1;
}

void I2C_STOP()
{
I2C_IDLE();
PEN	=	1;
}

unsigned char I2C_WRITE (unsigned char I2C_WRITEDATA)
{
I2C_IDLE();
SSPBUF	=	I2C_WRITEDATA;
return (!ACKSTAT);	//	returns 1 if transmission is acknowledged
}

int I2C_READ (unsigned char ACK)
{
unsigned char I2C_READDATA;
RCEN	=	1;
I2C_IDLE();
I2C_READDATA	=	SSPBUF;
I2C_IDLE();

if(ACK)
{
ACKDT	=	0;
}
else 
{
ACKDT	=	1;
}
ACKEN	=	1;
return (I2C_READDATA);
}

unsigned char READ_ADC()
{
I2C_START();
I2C_WRITE(0xD0);
I2C_WRITE(0x88);
I2C_RESTART();

I2C_WRITE(0xD1);
high_data = I2C_READ(1);
low_data = I2C_READ(1);
byte2 = I2C_READ(0);

I2C_STOP();

final_data = (high_data * 256) + low_data;

return final_data;
}

void lcd_init()
{
lcd_cmd(0x30);      // Configure the LCD in 8-bit mode, 1 line and 5x7 font
lcd_cmd(0x0c);      // display on and cursor off
lcd_cmd(0x01);      // clear display screen
lcd_cmd(0x06);      // increment cursor
lcd_cmd(0x80);      // set cursor to 1st line
}

void lcd_cmd(unsigned char c)
{
output_b(c);
output_low(RS);
output_high(EN);
delay_ms(15);
output_low(EN);
}

void lcd_data(unsigned char z)
{
output_b(z);
output_high(RS);
output_high(EN);
delay_ms(15);
output_low(EN);
}

What I'm doing wrong?