LCD.c
/*
* LCD interface example
* Uses routines from delay.c
* 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):
*
* PORTD bits 0-3 are connected to the LCD data bits 4-7 (high nibble)
* PORTC bit 0 is connected to the LCD RS input (register select)
* PORTC bit 2 is connected to the LCD EN bit (enable)
*
* To use these routines, set up the port I/O (TRISC, TRISD) then
* call lcd_init(), then other routines as required.
*
*/
#ifndef _XTAL_FREQ
// Unless specified elsewhere, 4MHz system frequency is assumed
#define _XTAL_FREQ 20000000
#endif
#include <htc.h>
#include "lcd.h"
__CONFIG( HS & WDTDIS & PWRTDIS & BORDIS & LVPDIS & WRTEN & DEBUGDIS & UNPROTECT);
#define LCD_RS RC0
#define LCD_RW RC1
#define LCD_EN RC2
#define LCD_DATA PORTD
#define LCD_STROBE() ((LCD_EN = 1),(LCD_EN=0))
/* write a byte to the LCD in 4 bit mode */
void
lcd_write(unsigned char c)
{
__delay_us(200);
LCD_DATA = ( ( c >> 4 ) & 0x0F );
LCD_STROBE();
LCD_DATA = ( c & 0x0F );
LCD_STROBE();
}
/*
* Clear and home the LCD
*/
void
lcd_clear(void)
{
LCD_RS = 0;
lcd_write(0x1);
__delay_ms(20);
}
/* write a string of chars to the LCD */
void
lcd_puts(const char * s)
{
LCD_RS = 1; // write characters
while(*s)
lcd_write(*s++);
}
/* write one character to the LCD */
void
lcd_putch(char c)
{
LCD_RS = 1; // write characters
lcd_write( c );
}
/*
* Go to the specified position
*/
void
lcd_goto(unsigned char pos)
{
LCD_RS = 0;
lcd_write(0x80+pos);
}
/* initialise the LCD - put into 4 bit mode */
void
lcd_init()
{
TRISC=0;
TRISD=0;
PORTC=0;
PORTD=0;
char init_value;
ADCON1 = 7; // Disable analog pins on PORTE
init_value = 0x3;
LCD_RS = 0;
LCD_EN = 0;
LCD_RW = 0;
__delay_ms(30); // wait 15mSec after power applied,
LCD_DATA = init_value;
LCD_STROBE();
__delay_ms(20);
LCD_STROBE();
__delay_us(200);
LCD_STROBE();
__delay_us(200);
LCD_DATA = 2; // Four bit mode
LCD_STROBE();
lcd_write(0x28); // Set interface length
lcd_write(0xF); // Display On, Cursor On, Cursor Blink
lcd_clear(); // Clear screen
lcd_write(0x6); // Set entry Mode
}
///////////////////////////////////////////////////////////////////////////////////////////
main.c
#include <htc.h>
#include "lcd.h"
void
main(void)
{
lcd_init();
lcd_goto(0); // select first line
lcd_puts("Welcome");
lcd_goto(0x40); // Select second line
lcd_puts("Hello world");
for(;
;
}
//////////////////////////////////////////////////////////////////