Không hiển thị được LCD, giúp mình với

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Nguyên văn bởi ngdnhanbk

Mình làm mạch hiển thị theo sơ đồ nguyên lý sau

và sử dụng file lcd_lib_4bit.c đã được post ở diễn đàn

#include <stddef.h>

#define LCD_RS          PIN_D0
#define LCD_RW          PIN_D1
#define LCD_EN          PIN_D2
#define LCD_D4          PIN_D4
#define LCD_D5          PIN_D5
#define LCD_D6          PIN_D6
#define LCD_D7          PIN_D7

// misc display defines-
#define Line_1          0x80
#define Line_2          0xC0
#define Clear_Scr       0x01
#separate void LCD_Init ();// ham khoi tao LCD
#separate void LCD_SetPosition ( unsigned int cX );//Thiet lap vi tri con tro
#separate void LCD_PutChar ( unsigned int cX );// Ham viet1kitu/1chuoi len LCD
#separate void LCD_PutCmd ( unsigned int cX) ;// Ham gui lenh len LCD
#separate void LCD_PulseEnable ( void );// Xung kich hoat
#separate void LCD_SetData ( unsigned int cX );// Dat du lieu len chan Data


// prototype statements

// D/n Cong
#use standard_io (D)
//#use standard_io (D)

//khoi tao LCD**********************************************
#separate void LCD_Init ()
    {
    LCD_SetData ( 0x00 );
    delay_ms(20);       /* wait enough time after Vdd rise >> 15ms */
    output_low ( LCD_RS );// che do gui lenh
    LCD_SetData ( 0x03 );   /* init with specific nibbles to start 4-bit mode */
    LCD_PulseEnable();
    LCD_PulseEnable();
    LCD_PulseEnable();
    LCD_SetData ( 0x02 );   /* set 4-bit interface */
    LCD_PulseEnable();      /* send dual nibbles hereafter, MSN first */
    LCD_PutCmd ( 0x2C );    /* function set (all lines, 5x7 characters) */
    LCD_PutCmd ( 0x0C );    /* display ON, cursor off, no blink */
    LCD_PutCmd ( 0x06 );    /* entry mode set, increment & scroll left */
    LCD_PutCmd ( 0x01 );    /* clear display */

    // Init for BarGraph

    }

#separate void LCD_SetPosition ( unsigned int cX )
    {
    /* this subroutine works specifically for 4-bit Port A */
    LCD_SetData ( swap ( cX ) | 0x08 );
    LCD_PulseEnable();
    LCD_SetData ( swap ( cX ) );
    LCD_PulseEnable();
    }

#separate void LCD_PutChar ( unsigned int cX )
    {
    /* this subroutine works specifically for 4-bit Port A */
        output_high ( LCD_RS );
        LCD_PutCmd( cX );
        output_low ( LCD_RS );
    }

#separate void LCD_PutCmd ( unsigned int cX )
    {
    /* this subroutine works specifically for 4-bit Port A */
    LCD_SetData ( swap ( cX ) );     /* send high nibble */
    LCD_PulseEnable();
    LCD_SetData ( swap ( cX ) );     /* send low nibble */
    LCD_PulseEnable();
    }
#separate void LCD_PulseEnable ( void )
    {
    output_high ( LCD_EN );
    delay_us ( 3 );         // was 10
    output_low ( LCD_EN );
    delay_ms ( 3 );         // was 5
    }

#separate void LCD_SetData ( unsigned int cX )
    {
    output_bit ( LCD_D4, cX & 0x01 );
    output_bit ( LCD_D5, cX & 0x02 );
    output_bit ( LCD_D6, cX & 0x04 );
    output_bit ( LCD_D7, cX & 0x08 );
    }

Chương trình hiển thị

#include <16F887.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#include "lcd_lib_4bit.c"
void main()
{
set_tris_d(0x00);
LCD_init();
LCD_putchar('X');
delay_ms(100);
LCD_putchar('I');
delay_ms(100);
LCD_putchar('N');
delay_ms(100);
LCD_putchar(' ');
delay_ms(100);
LCD_putchar('C');
delay_ms(100);
LCD_putchar('H');
delay_ms(100);
LCD_putchar('A');
delay_ms(100);
LCD_putchar('O');
delay_ms(100);
}

Nhưng chỉ hiện ra cái màn hình trắng trơn, ai chỉ giúp mình sai chỗ nào. Cảm ơn

code này thiếu lệnh: lcd_gotoxy(0,0); // lệnh này đặt trước LCD_putchar('X');

lệnh này có tác dụng là thiết lập vị trí hiển thị