LCD1602

liquid crystal display 液晶显示屏，一种字符型液晶显示模块，可以显示 16*2 个字符，每个字符是 5*7 点阵。

P0 P2 会和数码管、LED 一定程度上冲突。

地。
Vcc。
调对比度的。
RS：数据指令端。1代表 DB 是数据，0代表是指令。
RW：1读0写。
E：类似时钟的使能。高电平有效，下降沿执行。
DB：并行输入。一个字节长。
BG：背光灯电源。

内部结构图

类似 SMG，想显示1并不是直接输入1，而是操纵数码管右侧一竖被点亮。字模库起的就是这个作用，里面有固定的 ROM 和用户课自定义的 RAM。

DDRAM 长于屏幕，可以通过移平实现滚动效果。

AC address controller，可以自动移位写入数据。

字模库中的数据大多数和 ASCII 码是一样的。

指令

初始化指令

初始化要做哪些操作？

规定显示区域（如8位数据接口，2行显示，5*7点阵，即为0011 10xx，如果取0即为 0x38.）。

显示的模式设置（如开启显示，关闭光标，关闭光标闪烁：0000 1101，即 0x0D）。

进入模式设置（如读写后光标++，屏幕不动：0000 0110,0x06。如果是滚动屏幕则为）。

清屏（0x01）。

显示指令

先设置 DDRAM 初始地址，0x80|AC（开头的8是 DDRAM 固定指令信息不能改。后面的全是0，与 AC 光标位置做与，AC 不同位置的值见 DDRAM 地址表）.

然后发送数据。

时序

模块化

第一阶段我们先编写 LCD1602 模块化编程代码，这一部分主要显示静态内容，用于程序编写过程中显示变量进行调试。

目标模块化函数：

//LCD1602.h
#ifndef __LCD1602_H__
#define __LCD1602_H__

#include "reg52.h"
#include "intrins.h"
sbit LCD_RS=P2^6;
sbit LCD_RW=P2^5;
sbit LCD_E=P2^7;
#define LCD_DATAPORT P0

void LCD_Delay1ms();		//@11.0592MHz
void LCD_WriteCommand(unsigned char Command);
void LCD_WriteData(unsigned char Data);
void LCD_Init();
void LCD_SetCursor(unsigned char line, unsigned char column);
unsigned int LCD_Pow(unsigned char x, unsigned char y);
void LCD_ShowChar(unsigned char line, unsigned char column, unsigned char c);
void LCD_ShowString(unsigned char line, unsigned char column, unsigned char str[]);
void LCD_ShowNum(unsigned char line, unsigned char column, unsigned int num, unsigned char length);
void LCD_ShowSignedNum(unsigned char line, unsigned char column, int num, unsigned char length);
void LCD_ShowHexNum(unsigned char line, unsigned char column, unsigned int num, unsigned char length);
void LCD_ShowBinNum(unsigned char line, unsigned char column, unsigned int num, unsigned char length);
#endif

//LCD1602.c
#include "LCD1602.H"

void LCD_Delay1ms()		//@11.0592MHz
{
	unsigned char i, j;

	_nop_();
	_nop_();
	_nop_();
	i = 11;
	j = 190;
	do
	{
		while (--j);
	} while (--i);
}

void LCD_WriteCommand(unsigned char Command){
	LCD_RS=0;
	LCD_RW=0;
	LCD_E=0;
	LCD_DATAPORT=Command;
	LCD_Delay1ms();
	LCD_E=1;
	LCD_Delay1ms();
	LCD_E=0;
}

void LCD_WriteData(unsigned char Data){
	LCD_RS=1;
	LCD_RW=0;
	LCD_E=0;
	LCD_DATAPORT=Data;
	LCD_Delay1ms();
	LCD_E=1;
	LCD_Delay1ms();
	LCD_E=0;
}

void LCD_Init(){
	LCD_WriteCommand(0x38);
	LCD_WriteCommand(0x0C);
	LCD_WriteCommand(0x06);
	LCD_WriteCommand(0x01);
}

void LCD_SetCursor(unsigned char line, unsigned char column){
	if(line==1){
		LCD_WriteCommand(0x80|(column-1));
	}
	else{
		LCD_WriteCommand(0x80|(column-1)+0x40);
	}
}

unsigned int LCD_Pow(unsigned char x, unsigned char y){
	unsigned char i=y;
	unsigned int res=1;
	for(;i>0;i--)res*=x;
	return res;
}

void LCD_ShowChar(unsigned char line, unsigned char column, unsigned char c){
	LCD_SetCursor(line, column);
	LCD_WriteData(c);
}

void LCD_ShowString(unsigned char line, unsigned char column, unsigned char str[]){
	unsigned int i=0;
	LCD_SetCursor(line, column);
	while(str[i]!='\0'){
		LCD_WriteData(str[i]);
		i++;
	}
}

void LCD_ShowNum(unsigned char line, unsigned char column, unsigned int num, unsigned char length){
	unsigned char i;
	unsigned base;
	LCD_SetCursor(line, column);
	for(i=length;i>0;i--){
		base=LCD_Pow(10, i-1);
		LCD_WriteData(num/base%10+'0');	
	}
}

void LCD_ShowBinNum(unsigned char line, unsigned char column, unsigned int num, unsigned char length){
	unsigned char i;
	unsigned char base;
	unsigned char single_num;
	LCD_SetCursor(line, column);
	for(i=length;i>0;i--){
		base=LCD_Pow(2, i-1);
		single_num=num/base%2+'0';
		LCD_WriteData(single_num);	
	}
}

void LCD_ShowHexNum(unsigned char line, unsigned char column, unsigned int num, unsigned char length){
	unsigned char i;
	unsigned char base;
	unsigned char single_num;
	LCD_SetCursor(line, column);
	for(i=length;i>0;i--){
		base=LCD_Pow(16, i-1);
		single_num=num/base%16;
		if(single_num<=9)single_num+='0';
		else single_num+='A'-10;
		LCD_WriteData(single_num);	
	}
}

void LCD_ShowSignedNum(unsigned char line, unsigned char column, int num, unsigned char length){
	unsigned char i;
	unsigned base;
	LCD_SetCursor(line, column);
	if(num>0)LCD_WriteData('+');
	else {LCD_WriteData('-');num=-num;}
	for(i=length;i>0;i--){
		base=LCD_Pow(10, i-1);
		LCD_WriteData(num/base%10+'0');	
	}
}