1、掌握变量的作用域及存储类别。

局部变量

函数内部声明的变量，只在函数内部有效，在本函数以外是不能使用的，叫局部变量。

全局变量

在函数外部声明的变量就是全局变量，一个源程序可以包含一个或多个函数，全局变量的作用范围是从它开始声明的位置一直到程序结束。

全局变量的副作用

1)降低函数的独立性，对任何一个函数的修改都可能影响到其他函数。

2）降低函数的通用性，不利于函数的重复利用。

3）降低程序的清晰度，每个函数执行都有可能改变全局变量值，无法清楚判断每个时刻的全局变量的值。

4)全局变量永久占用内存单元。

原则：能用局部变量就不用全局变量

全局变量和局部变量同名，在局部变量作用域范围内，局部变量有效。

自动变量

函数中的局部变量，如果不加static关键词修饰，都属于自动变量，也叫动态变量。

静态变量

所有的全局变量都属于静态变量，局部变量加了static关键词修饰的话，也是静态变量

2、了解点阵的显示原理，理解点阵动画显示原理。

点阵的显示原理是多个LED小灯组合在一起，点亮不同的LED小灯集合下来组成不同的图案，点阵的动画显示实际上就是不同图案的高帧变化。

3、独立完成点阵显示I❤U向下移动的程序。

clude <REGX52.H>
sbit addr0 = P1^0;
sbit addr1 = P1^1;
sbit addr2 = P1^2;
sbit addr3 = P1^3;
sbit ENLED = P1^4;
unsigned char code LedBuff[] = {
0xC3,0xE7,0xE7,0xE7,0xE7,0xE7,0xC3,0xFF,
0xE7,0xC3,0x81,0x00,0x00,0x99,0xFF,0xC3,
0x81,0x99,0x99,0x99,0x99,0x99,0xFF,0xFF,
};unsigned int flag1s = 0;
unsigned int cnt = 0,i = 0;void main()
{ENLED = 0;addr3 = 0;TMOD = 0x01;TH0 = 0xfc;TL0 = 0x67;TR0 = 1;while(1) 
{if(TF0 == 1){TF0 = 0;cnt++;if(cnt >= 5){cnt = 0;flag1s++;}}P0 = 0xff;switch (i){case 0 :addr0 = 0;addr1 = 0;addr2 = 0;P0 = LedBuff[flag1s + 7];i++;break;case 1 :addr0 = 1;addr1 = 0;addr2 = 0;P0 = LedBuff[flag1s + 6];i++;break;case 2 :addr0 = 0;addr1 = 1;addr2 = 0;P0 = LedBuff[flag1s + 5];i++;break;case 3 :addr0 = 1;addr1 = 1;addr2 = 0;P0 = LedBuff[flag1s + 4];i++;break;case 4 :addr0 = 0;addr1 = 0;addr2 = 1;P0 = LedBuff[flag1s + 3];i++;break;case 5 :addr0 = 1;addr1 = 0;addr2 = 1;P0 = LedBuff[flag1s + 2];i++;break;case 6 :addr0 = 0;addr1 = 1;addr2 = 1;P0 = LedBuff[flag1s + 1];i++;break;case 7 :addr0 = 1;addr1 = 1;addr2 = 1;P0 = LedBuff[flag1s + 0];i=0;break;default:break;}if(flag1s >= 16){flag1s = 0;}}
}

4、独立完成点阵显示I❤U向右移动的程序。

#include <REGX52.H>
sbit addr0 = P1^0;
sbit addr1 = P1^1;
sbit addr2 = P1^2;
sbit addr3 = P1^3;
sbit ENLED = P1^4;
unsigned char code LedBuff[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0x7D,0x01,0x01,0x7D,0xFF,0xFF,0xE3,0xC1,0x81,0x03,0x03,0x81,0xC1,0xE3,0xFF,0xFF,0x81,0x01,0x3F,0x3F,0x3F,0x01,0x81,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF
};unsigned int flag1s = 0;
unsigned int cnt = 0,i = 0;void main()
{ENLED = 0;addr3 = 0;TMOD = 0x01;TH0 = 0xfc;TL0 = 0x67;TR0 = 1;while(1) 
{if(TF0 == 1){TF0 = 0;cnt++;if(cnt >= 5){cnt = 0;flag1s++;}}P0 = 0xff;switch (i){case 0 :addr0 = 0;addr1 = 0;addr2 = 0;P0 = LedBuff[flag1s + 7];i++;break;case 1 :addr0 = 1;addr1 = 0;addr2 = 0;P0 = LedBuff[flag1s + 6];i++;break;case 2 :addr0 = 0;addr1 = 1;addr2 = 0;P0 = LedBuff[flag1s + 5];i++;break;case 3 :addr0 = 1;addr1 = 1;addr2 = 0;P0 = LedBuff[flag1s + 4];i++;break;case 4 :addr0 = 0;addr1 = 0;addr2 = 1;P0 = LedBuff[flag1s + 3];i++;break;case 5 :addr0 = 1;addr1 = 0;addr2 = 1;P0 = LedBuff[flag1s + 2];i++;break;case 6 :addr0 = 0;addr1 = 1;addr2 = 1;P0 = LedBuff[flag1s + 1];i++;break;case 7 :addr0 = 1;addr1 = 1;addr2 = 1;P0 = LedBuff[flag1s + 0];i=0;break;default:break;}if(flag1s >= 32){flag1s = 0;}}
}

5、用点阵做一个9到0的倒计时牌显示。

#include <REGX52.H>
sbit addr0 = P1^0;
sbit addr1 = P1^1;
sbit addr2 = P1^2;
sbit addr3 = P1^3;
sbit ENLED = P1^4;
unsigned char code LedBuff[][8] = {
0xFF,0xE7,0xE7,0xE7,0xE7,0xE7,0xE7,0xFF,0xFF,0xE3,0xDF,0xDF,0xEF,0xF7,0xC3,0xFF,
0xFF,0xC3,0xDF,0xDF,0xE3,0xDF,0xDF,0xC3,0xFF,0xEF,0xE7,0xEB,0xC1,0xEF,0xEF,0xEF,
0xFF,0xC3,0xFB,0xC3,0xDF,0xDF,0xDF,0xE3,0xFF,0xC3,0xDF,0xDF,0xC3,0xDB,0xDB,0xC3,
0xFF,0xC3,0xDF,0xEF,0xF7,0xF7,0xF7,0xF7,0xFF,0xC3,0xDB,0xDB,0xE7,0xDB,0xDB,0xC3,
0xFF,0xC3,0xDB,0xDB,0xC3,0xDF,0xDF,0xEF,0xFF,0xE7,0xDB,0xDB,0xDB,0xDB,0xDB,0xE7,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
};unsigned int flag1s = 0;
unsigned int cnt = 0,i = 0;void main()
{ENLED = 0;addr3 = 0;TMOD = 0x01;TH0 = 0xfc;TL0 = 0x67;TR0 = 1;while(1) 
{if(TF0 == 1){TF0 = 0;cnt++;if(cnt >= 10){cnt = 0;flag1s++;}}P0 = 0xff;switch (i){case 0 :addr0 = 0;addr1 = 0;addr2 = 0;P0 = LedBuff[flag1s][0];i++;break;case 1 :addr0 = 1;addr1 = 0;addr2 = 0;P0 = LedBuff[flag1s][1];i++;break;case 2 :addr0 = 0;addr1 = 1;addr2 = 0;P0 = LedBuff[flag1s][2];i++;break;case 3 :addr0 = 1;addr1 = 1;addr2 = 0;P0 = LedBuff[flag1s][3];i++;break;case 4 :addr0 = 0;addr1 = 0;addr2 = 1;P0 = LedBuff[flag1s][4];i++;break;case 5 :addr0 = 1;addr1 = 0;addr2 = 1;P0 = LedBuff[flag1s][5];i++;break;case 6 :addr0 = 0;addr1 = 1;addr2 = 1;P0 = LedBuff[flag1s][6];i++;break;case 7 :addr0 = 1;addr1 = 1;addr2 = 1;P0 = LedBuff[flag1s][7];i=0;break;default:break;}if(flag1s >= 10){flag1s = 0;}}
}

6、尝试实现流水灯、数码管和点阵的同时显

#include <REGX52.H>
sbit addr0 = P1^0;
sbit addr1 = P1^1;
sbit addr2 = P1^2;
sbit addr3 = P1^3;
sbit ENLED = P1^4;
unsigned int i = 0;void main()
{EA = 1;ENLED = 0;TMOD = 0x01;TH0 = 0xfc;TL0 = 0x67;ET0 = 1;TR0 = 1;while(1) 
{}	
}
void InterruptTimer0() interrupt 1
{TH0 = 0xfc;TL0 = 0x67;P0 = 0xff;switch (i){case 0 :addr3 = 0;addr0 = 0;addr1 = 0;addr2 = 0;P0 = 0;i++;break;case 1 :addr3 = 0;addr0 = 1;addr1 = 0;addr2 = 0;P0 = 0;i++;break;case 2 :addr3 = 0;addr0 = 0;addr1 = 1;addr2 = 0;P0 = 0;i++;break;case 3 :addr3 = 0;addr0 = 1;addr1 = 1;addr2 = 0;P0 = 0;i++;break;case 4 :addr3 = 0;addr0 = 0;addr1 = 0;addr2 = 1;P0 = 0;i++;break;case 5 :addr3 = 0;addr0 = 1;addr1 = 0;addr2 = 1;P0 = 0;i++;break;case 6 :addr3 = 0;addr0 = 1;addr1 = 0;addr2 = 1;P0 = 0;i++;break;case 7 :addr3 = 0;addr0 = 1;addr1 = 0;addr2 = 1;P0 = 0;i++;break;case 8 :addr3 = 1;addr0 = 0;addr1 = 0;addr2 = 0;P0 = 0;i++;break;case 9 :addr3 = 1;addr0 = 1;addr1 = 0;addr2 = 0;P0 = 0;i++;break;case 10 :addr3 = 1;addr0 =0;addr1 = 1;addr2 = 0;P0 = 0;i++;break;case 11 :addr3 = 1;addr0 = 1;addr1 = 1;addr2 = 0;P0 = 0;i++;break;case 12 :addr3 = 1;addr0 = 0;addr1 = 0;addr2 = 1;P0 = 0;i++;break;case 13 :addr3 = 1;addr0 = 1;addr1 = 0;addr2 = 1;P0 = 0;i++;break;case 14 :addr3 = 1;addr0 = 0;addr1 = 1;addr2 = 1;P0 = 0;i=0;break;default:break;}}