to drive LCD in 4 bit function.

1. /********PIC16F887*******
HI-Tech C compiler
Programmer : http://vto22012.blogspot.com/
***********************************
*/
#include <htc.h>
#define _XTAL_FREQ 20000000 //crystal speed 20Mhz
__CONFIG(0X3F32); //set configuration bits. Refer to PIC datasheet.
#include <stdio.h> // standard I/O c language
/********LCD Driver start ************************************************/
/* LCD controller
// (max characters is 40)
// Initialization: lcd_init();
// To print a string: printf("Hello World");
// A few more formatting subroutines are available.
// See towards the end of this page.
// macros to isolate interface dependencies
// LCD is connected to PORTD */
#define LCDPort PORTD
#define LCDTris TRISD
#define Epin 6
#define RWpin 5
#define RSpin 4
#define BUSYpin 3
#define DATA0pin 0
#define DATA1pin 1
#define DATA2pin 2
#define DATA3pin 3
#define EHIGH bitset(LCDPort, Epin)
#define ELOW bitclr(LCDPort, Epin)
#define E_OUTPUT bitclr(LCDTris, Epin)
#define RSHIGH bitset(LCDPort, RSpin)
#define RSLOW bitclr(LCDPort, RSpin)
#define RS_OUTPUT bitclr(LCDTris, RSpin)
#define RWHIGH bitset(LCDPort, RWpin)
#define RWLOW bitclr(LCDPort, RWpin)
#define RW_OUTPUT bitclr(LCDTris, RWpin)
#define BUSY_FLAG bittst(LCDPort, BUSYpin)
#define DATA_DIR_RD
{bitset(LCDTris,DATA3pin);bitset(LCDTris,DATA2pin);bitset(LCDTris,DATA1pin);bits
et(LCDTris,DATA0pin);}
#define DATA_DIR_WR
{bitclr(LCDTris,DATA3pin);bitclr(LCDTris,DATA2pin);bitclr(LCDTris,DATA1pin);bitc
lr(LCDTris,DATA0pin);}
#define OUTPUT_DATA(x) {int aval=LCDPort&0xF0; x = x & 0x0F; LCDPort=aval+x;}
// some common defines
#define bitset(var,bitno) ((var) |= (1 << (bitno)))
#define bitclr(var,bitno) ((var) &= ~(1 << (bitno)))
#define bittst(var,bitno) (var & (1 << (bitno)))
void epulse(void){
__delay_us(1);

2. EHIGH;
__delay_us(1);
ELOW;
__delay_us(1);
}
void lcd_write(
unsigned char cmd, unsigned char data_flag, unsigned char chk_busy,
unsigned char dflag){
char bflag,c;
if (chk_busy) {
RSLOW; //RS = 0 to check busy
// check busy
DATA_DIR_RD; //set data pins all inputs
RWHIGH; // R/W = 1, for read
do {
EHIGH;
__delay_us(1); // upper 4 bits
bflag = BUSY_FLAG;
ELOW;
__delay_us(1);
epulse();
} while(bflag);
} else {
__delay_ms(10); // don't use busy, just delay
}
DATA_DIR_WR;
if (data_flag) RSHIGH; // RS=1, data byte
else RSLOW; // RS=0, command byte
// device is not busy
RWLOW; // R/W = 0, for write
c = cmd >> 4; // send upper 4 bits
OUTPUT_DATA(c);
epulse();
if (dflag) {
c = cmd & 0x0F; //send lower 4 bits
OUTPUT_DATA(c);
epulse();
}
}
void lcd_init(void) {
// configure, see control pins as outputs
// initialize as low
E_OUTPUT; RS_OUTPUT; RW_OUTPUT;
ELOW; RSLOW; RWLOW;
__delay_ms(25); //wait for device to settle
__delay_ms(25);
lcd_write(0x20,0,0,0); // 4 bit interface
lcd_write(0x28,0,0,1); // 2 line display, 5x7 font
lcd_write(0x28,0,0,1); // repeat
lcd_write(0x06,0,0,1); // enable display
lcd_write(0x0C,0,0,1); // turn display on; cursor, blink is off
lcd_write(0x01,0,0,1); // clear display, move cursor to home
__delay_ms(3); // wait for busy flag to be ready
}
// send 8 bit char to LCD
void putch (char c) {
lcd_write(c,1,1,1);
}

3. void lcd_clear(void){
lcd_write(0x01,0,0,1); // clear display, move cursor to home
}
/* go to the specified position */
void lcd_goto(unsigned char row, unsigned char pos)
{
switch(row){
case 1:{lcd_write(0x80+pos,0,1,1);break;}
case 2:{lcd_write(0xC0+pos,0,1,1);break;}
case 3:{lcd_write(0x94+pos,0,1,1);break;}
case 4:{lcd_write(0xD4+pos,0,1,1);break;}
}
}
void lcd_shiftleft(void){
lcd_write(0x18,0,1,1); // shift left
}
void lcd_shiftright(void){
lcd_write(0x1C,0,1,1); // shift right
}
void lcd_blinkcursor(void){
lcd_write(0x0F,0,1,1); // displays and blink a cursor
}
void lcd_printbar(int bar){
for(int i=0; i<bar; i++){
lcd_write(0xFF,1,1,1); // print bars on the LCD
}
}
void lcd_string(const char *s) //send a string to display
in the lcd
{
unsigned char i=0;
while (s && *s)lcd_write(*s++,1,1,1);
}
/********************LCD Driver
End****************************************************/
/*******************start main program *************************************/
void main(void)
{
TRISD = 0b00000000; // configure all RD pin as output
PORTD = 0b00000000; // reset all RD pin to 0 or off
condition
ANSEL = 0; // Configure AN pins as digital
ANSELH = 0;
C1ON = 0; // Disable comparators
C2ON = 0;
lcd_init(); // initialise LCD
while(1){ // loop forever
lcd_goto(1,0); //Display start at line 1 and position 0
printf("Tutorial PIC"); //display
lcd_goto(2,0); //Display start at line 2 position 0
printf("visit:vto22012");

4. //can use normal printf function like printf("Convert number %d",temp);
}
}
/***********************main program
end****************************************/