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):
 *
 *  PORTC bits 0-3 are connected to the LCD data bits 4-7 (high nibble)
 *  PORTBA bit 4 is connected to the LCD RS input (register select)
 *  PORTA bit 6 is connected to the LCD EN bit (enable)
 *
 *  To use these routines, set up the port I/O (TRISA, TRISC) then
 *  call lcd_init(), then other routines as required.
 *
 */

#include    <pic.h>
#include    "lcd.h"
#include    "delay.h"

#define LCD_RS RA0
#define LCD_RW RA1
#define LCD_EN RA2

#define LCD_DATA    PORTC

#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)
{
    DelayUs(40);
    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);
    DelayMs(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_goto(unsigned char pos)
{
    LCD_RS = 0;
    lcd_write(0x80+pos);
}

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

    LCD_RS = 0;
    LCD_EN = 0;
    LCD_RW = 0;

    DelayMs(15);    // wait 15mSec after power applied,
    LCD_DATA     = init_value;
    LCD_STROBE();
    DelayMs(5);
    LCD_STROBE();
    DelayUs(200);
    LCD_STROBE();
    DelayUs(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
}