[phatcddt08a]

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

cách này quá thủ công .bạn cho vào mảng rồi dùng vòng lặp ghi ra một lượt cho dễ