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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。
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地。
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Vcc。
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调对比度的。
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RS：数据指令端。1代表 DB 是数据，0代表是指令。
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RW：1读0写。
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E：类似时钟的使能。高电平有效，下降沿执行。
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DB：并行输入。一个字节长。
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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 P0void 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'); }
}
如果希望屏幕滚动，一定时间执行一次LCD_WriteCommand(0x18); 屏幕左移指令。