Tìm lỗi code 8051 kết nối LCD

Code của em không cho khi chạy thì không xuất chữ ra màn hình ?? ai có thể giúp em ko?

#include"LCD4.h"
#include"Delay.h"
#include"main.h"
#include"Port.h"

/*----------------------------------------------
	_LCD_CLEAR: 0x01
	_LCD_RETURN_HOME: 0x02
	_LCD_ENTRY_MODE: 0x06
	_LCD_4BIT_2LINE_FONT_5x8: 0x28
	_LCD_TURN_ON: 0x0C
-*--------------------------------------------*/

void delay_us(unsigned char n){
	while(n--);
}

void lcdWriteHighNibble(unsigned char dat){
	LCD_D7 = dat & 0x80;
	LCD_D6 = dat & 0x40;
	LCD_D5 = dat & 0x20;
	LCD_D4 = dat & 0x10;
}

void lcdWriteLowNibble(unsigned char dat){
	LCD_D7 = dat & 0x08;
	LCD_D6 = dat & 0x04;
	LCD_D5 = dat & 0x02;
	LCD_D4 = dat & 0x01;
}

void lcdCmd(unsigned char cmd){
	LCD_RS = 0;

	lcdWriteHighNibble(cmd);
	LCD_RS = 1;
	LCD_RS = 0;

	lcdWriteLowNibble(cmd);
	LCD_RS = 1;
	LCD_RS = 0;

	if(cmd <= 0x02)
		delay_ms(2);
	else
		delay_us(37);
}

void initLCD(){

	LCD_RS = 0;

	delay_ms(20);

	lcdWriteLowNibble(0x03);
	LCD_EN = 1;
	LCD_EN = 0;
	delay_ms(5);

	lcdWriteLowNibble(0x03);
	LCD_EN = 1;
	LCD_EN = 0;
	delay_us(100);

	lcdWriteLowNibble(0x03);
	LCD_EN = 1;
	LCD_EN = 0;
	delay_ms(1);

	lcdWriteLowNibble(0x02);// khoi tao dung 4 bit
	LCD_EN = 1;
	LCD_EN = 0;
	delay_ms(1);


	//edit lcd
	lcdCmd(_LCD_4BIT_2LINE_FONT_5x7);
	lcdCmd(_LCD_TURN_ON);
	lcdCmd(_LCD_CLEAR);
	lcdCmd(_LCD_ENTRY_MODE);
}

void showChrCP(unsigned char dat){
	LCD_RS = 1;
	
	lcdWriteHighNibble(dat);
	LCD_EN = 1;
	LCD_EN = 0;

	lcdWriteLowNibble(dat);
	LCD_EN = 1;
	LCD_EN = 0;
   	
	delay_us(37 + 4);
}

hàm main

void main(void){
	initLCD();
	showChrCP('a');
}