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Mình đang cố đọc hiểu cách lập trình LCD qua C, nhưng mình không hiểu đoạn này lắm, rất mong được giải đáp:
mã lệnh "code" dùng để làm gì? và dấu "*" để diễn đạt điều gì?
Đoạn 2,
Nhất là cái câu LCD_PORT=cmd;
Đoạn 3:
Đặt tên biến kiểu *str là như thế nào?
Cả bài đó đây:
Code:
/* line1 to display on LCD */ code unsigned char *line1 = " noi dung 1 "; code unsigned char *line2 = " noi dung 2 "; code unsigned char *line3 = " noi dung 3 "; code unsigned char *line4 = " noi dung 4 ";
Đoạn 2,
Code:
void LCD_PutCmd(unsigned char cmd)
{
WaitReady(); // Wait for LCD ready
WriteCommand; // set LCD to send mode
LCD_PORT = cmd; // Prepare to send
LatchData; // latch data out
}
Đoạn 3:
Code:
void LCD_PrString(char *str)
{
while(*str!='\0')
{
LCD_PutChar(*str);
++str;
}
}
Cả bài đó đây:
Code:
/****************************************************************************/
/* */
/* File: lcd.c */
/* Author: Vu Ha Linh, Automatic Control Deparment */
/* Ha Noi university of technology */
/* */
/****************************************************************************/
/* */
/* Function: This module is a standard LCD (16x2) functions */
/* */
/* Input and Output parameters of those subroutines: */
/* void LCD_Init(void); */
/* void LCD_Position(unsigned char, unsigned char); */
/* void LCD_PutCmd(unsigned char); */
/* void LCD_PutChar(unsigned char); */
/* void LCD_PrString(char*); */
/* void LCD_Clear(void); */
/* void LCD_PrInteger(int); */
/* */
/* Note: Must be call LCD_Init() first at the begining of program */
/* */
/****************************************************************************/
/* */
/* History: */
/* Version: */
/* Date Writer Remark */
/* */
/* 30-07-2006 Vu Ha Linh Creating the first version */
/* */
/* */
/****************************************************************************/
#include <REGX51.H>
#include "lcd.h"
/*****************************************************************************
define Hardware address
it can changed by user
*****************************************************************************/
#define LCD_PORT P1
sbit LCD_RS = P3^2;
sbit LCD_RW = P3^3;
sbit LCD_EN = P3^4;
sbit LCD_D7 = P1^7;
#define ReadCommand {LCD_RS = 0; LCD_RW = 1;}
#define WriteCommand {LCD_RS = 0; LCD_RW = 0;}
#define WriteData {LCD_RS = 1; LCD_RW = 0;}
#define LatchData {LCD_EN = 1; LCD_EN = 0;}
/****************************************************************************
WaitReady function
Wait while LCD in execution time
*****************************************************************************/
void WaitReady(void)
{
ReadCommand; // Set Read command mode
LCD_D7 = 1;
while(LCD_D7){
LCD_EN = 0;
LCD_EN = 1; // Read bit D7
}
}
/****************************************************************************
LCD_PutCmd function
Write a control byte to LCD
Input : control byte
*****************************************************************************/
void LCD_PutCmd(unsigned char cmd)
{
WaitReady(); // Wait for LCD ready
WriteCommand; // set LCD to send mode
LCD_PORT = cmd; // Prepare to send
LatchData; // latch data out
}
/****************************************************************************
LCD_PutChar function
Write a ASCII symbol to LCD
Input: ASCII symbol
*****************************************************************************/
void LCD_PutChar(unsigned char ch)
{
WaitReady();
WriteData;
LCD_PORT = ch;
LatchData;
}
/*****************************************************************************
LCD_PrString function
Write a string to LCD
Input: string
******************************************************************************/
void LCD_PrString(char *str)
{
while(*str!='\0')
{
LCD_PutChar(*str);
++str;
}
}
/*****************************************************************************
LCD_Position function
Set the position of cursor on LCD
Input: row, column
******************************************************************************/
void LCD_Position(unsigned char row, unsigned char col)
{
LCD_PutCmd( (1<<7)|(row<<6)|col );
}
/*****************************************************************************
LCD_Clear function
Clear LCD
******************************************************************************/
void LCD_Clear()
{
LCD_PutCmd(LCD_CLEAR);
}
/*****************************************************************************
LCD_Init function
Prepare for display content. Must be called at first
******************************************************************************/
void LCD_Init()
{
LCD_PutCmd(0x30); // Data length setting, 8 bits
LCD_PutCmd(0x30); // Data length setting, 8 bits
LCD_PutCmd(0x30); // Data length setting, 8bits
LCD_PutCmd(LCD_FONT); // Function set: 8 bits, 2 lines, font 5x7
LCD_PutCmd(LCD_OFF); // Display and cursor OFF
LCD_PutCmd(LCD_CLEAR); // Clear display
LCD_PutCmd(LCD_MOVE_CURSOR); // Entry mode set: Increment mode, not shift
LCD_PutCmd(LCD_DISPLAY_ON); // Display ON
// LCD_PutCmd(LCD_BLINK_CURSOR); // Blink cursor
}
/****************************************************************************
LCD_PrInteger function
Display a integer decimal number on LCD
Input: a integer number
*****************************************************************************/
void LCD_PrInteger(int num)
{
int temp;
unsigned char i, c[5];
temp = num;
if (temp != 0) {
if (temp < 0) {
LCD_PutChar('-');
temp = -temp;
}
i = 0;
while(temp){
c[i++] = temp%10;
temp /= 10;
}
while(i) LCD_PutChar(c[--i] + '0');
}
else LCD_PutChar('0');
}
/************************* END OF FILE *******************************/
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