This document contains code for interfacing with an LCD display using a Hitachi HD44780 controller in 4-bit mode. It includes function definitions for initializing the LCD, writing data, clearing the screen, writing strings and characters to specific positions on the LCD. The main function calls lcd_init() to initialize the LCD, then uses printf() to write strings at different positions on the LCD to display text for testing the LCD interface.

1. /*website : http://picnelectronic.blogspot.com/
compiler : HI-TECH C compiler version 9.82
Programmer : HF
*/
#include <htc.h> //to include content before compiling
#define _XTAL_FREQ 20000000 //DEFINE CRYSTAL VALUE
__CONFIG(FOSC_HS & WDTE_OFF & PWRTE_ON & BOREN_OFF & MCLRE_ON &
LVP_OFF);
/*High speed crystal oscillator
Disable Watchdog Timer
Enable Power Up Timer
Disable Brown Out Reset
MCLR function is enabled
Disable Low Voltage Programming*/
/****************LCD FUNCTION START*************************/
/*
* LCD interface example
* This code will interface to a standard LCD controller
* like the Hitachi HD44780. It uses it in 4 bit mode, with
* the hardware connected as follows (the standard 14 pin
* LCD connector is used):
*
*
* To use these routines, set up the port I/O (TRISD) then
* call lcd_init(), then other routines as required.
* printf function (stdio.h) to write data to LCD
*/
#include <stdio.h>
#define LCD_RS RD0 //LCD configuration
#define LCD_EN RD1
#define LCD_D4 RD2
#define LCD_D5 RD3
#define LCD_D6 RD4
#define LCD_D7 RD5
#define LCD_PULSE() ((LCD_EN = 1),(LCD_EN=0))
/* write a byte to the LCD in 4 bit mode */
void lcd_write(unsigned char c)
{
__delay_us(40);
LCD_D4=(c>>4)&1; //LCD High nibble
LCD_D5=(c>>5)&1;
LCD_D6=(c>>6)&1;
LCD_D7=(c>>7)&1;

2. LCD_PULSE();
LCD_D4=(c>>0)&1; //LCD low Nibble
LCD_D5=(c>>1)&1;
LCD_D6=(c>>2)&1;
LCD_D7=(c>>3)&1;
LCD_PULSE();
}
void lcd_clear(void) //Clear and home the LCD
{
LCD_RS = 0;
lcd_write(0x1);
__delay_ms(2);
}
void lcd_string(const char * s) /* write a string of chars to
the LCD */
{
LCD_RS = 1; // write characters
while(*s)
lcd_write(*s++);
}
/* write one character to the LCD */
void lcd_char(char c)
{
LCD_RS = 1; // write characters
lcd_write( c );
}
void putch(char c)
{
LCD_RS = 1; // write characters
lcd_write( c );
}
/*
* Go to the specified position
*/
void lcd_goto(unsigned char row, unsigned char pos)
{
LCD_RS = 0;
switch(row){
case 0:{lcd_write(0x80+pos);break;}
case 1:{lcd_write(0xC0+pos);break;}
case 2:{lcd_write(0x94+pos);break;}
case 3:{lcd_write(0xD4+pos);break;}
}

3. }
/* initialise the LCD - put into 4 bit mode */
void lcd_init()
{
LCD_RS = 0;
LCD_EN = 0;
__delay_ms(15); // wait 15mSec after power applied,
LCD_D4=1;
LCD_D5=1;
LCD_D6=1;
LCD_D7=0;
LCD_PULSE();
__delay_ms(5);
LCD_PULSE();
__delay_us(200);
LCD_PULSE();
__delay_us(200);
// Four bit mode
LCD_D4=0;
LCD_D5=1;
LCD_D6=0;
LCD_D7=0;
LCD_PULSE();
lcd_write(0x28); // Set interface length
lcd_write(0x0C); // Display On, Cursor On, Cursor Blink
lcd_clear(); // Clear screen
lcd_write(0x6); // Set entry Mode
}
/*******************LCD FUNCTION END************************/
void main(void) // the main function
{
TRISD = 0b00000000; //Set PORTD as output
lcd_init(); //initialize LCD display
lcd_goto(0,0); //row 1 pos 1
printf("Tutorial LCD"); //display on LCD
lcd_goto(1,0); //row 2 pos 1
printf("Hitachi HD44780");
while(1){
}
}