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):
 *	
 *	PORTB bits 0-3 are connected to the LCD data bits 4-7 (high nibble)
 *	PORTB bit 4 is connected to the LCD RS input (register select)
 *	PORTB bit 5 is connected to the LCD EN bit (enable)
 *	
 *	To use these routines, set up the port I/O (TRISA, TRISD) then
 *	call lcd_init(), then other routines as required.
 *	
 */

#include	<htc.h>
#include	"lcd.h"

#define	LCD_RS RB4
#define LCD_EN RB5
#define LCD_DATA	PORTB
#define	LCD_STROBE()	((LCD_EN = 1),(__delay_ms(1)),(LCD_EN=0))

#define _XTAL_FREQ 20000000


/* write a byte to the LCD in 4 bit mode */

void
lcd_write(unsigned char c)
{
	__delay_us(40);
	LCD_DATA = (PORTB & 0xF0) | ( (c  >> 4) & 0x0F );
	LCD_STROBE();
	LCD_DATA = (PORTB & 0xF0) |  (c & 0x0F);
	LCD_STROBE();
}

/*
 * 	Clear and home the LCD
 */

void
lcd_clear(void)
{
	LCD_RS = 0;
	lcd_write(0x1);
	__delay_ms(2);
}

/* 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_gotorow(unsigned char pos)
{
	if(pos == 1){
	LCD_RS = 0;
	lcd_write(0x80 + 0);
	}

	if(pos == 2){
	LCD_RS = 0;
	lcd_write(0x80 + 0x40);
	}
	
}


void
lcd_goto(unsigned char pos)
{

	LCD_RS = 0;
	lcd_write(pos);
	
}


	
/* initialise the LCD - put into 4 bit mode */
void
lcd_init()
{
	char init_value;
	init_value = 0x3;

	LCD_RS = 0;
	LCD_EN = 0;
	
	__delay_ms(30);	// wait 15mSec after power applied,
	LCD_DATA	 = (PORTB & 0xF0) | (  0x3  & 0x0F  );
	LCD_STROBE();
	__delay_ms(20);
	LCD_STROBE();
	__delay_us(200);
	LCD_STROBE();
	__delay_us(200);
	LCD_DATA = (PORTB & 0xF0) | (  0x2   & 0x0F   );	// Four bit mode
	LCD_STROBE();

	lcd_write(0x10); // Set interface length 16
	lcd_write(0xC); // Display On, Cursor On, Cursor Blink
	lcd_clear();	// Clear screen
	lcd_write(0x6); // Set entry Mode
}