纯新手写的 51 单片机 矩阵键盘&数码管显示&定时器扫描 教程

下面是我的源代码（解析在后面）

//#include "STC15F2K60S2.H"
#include "reg52.h" 
#include "intrins.h"
#include "absacc.h"
//-----------------下方设置变量------------------

sfr P4=0xC0;

sbit R1=P3^0;
sbit R2=P3^1;
sbit R3=P3^2;
sbit R4=P3^3;   //R都是横向的

sbit C1=P3^4;
sbit C2=P3^5;
sbit C3=P4^2;
sbit C4=P4^4;   //C都是纵向的

sfr AUXR=0x8e;

unsigned char code SMG[18]={
   0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff};

unsigned char pos5,pos6,pos7;

unsigned char scanpoint=0;

unsigned char key_v,key_s=0;

int number=0;
//-----------------------------------------------

void Delay10ms()		//@11.0592MHz
{
   
	unsigned char i, j;

	i = 108;
	j = 145;
	do
	{
   
		while (--j);
	} while (--i);
}


void Select573(unsigned char channel)
{
   
	switch (channel) 
	{
   
		case 4:
		{
   
			P2=(P2&0x1f)|0x80;
		  break;}
		
			case 5:
		{
   
			P2=(P2&0x1f)|0xa0;
		  break;}
		
			case 6:
		{
   
			P2=(P2&0x1f)|0xc0;
		  break;}
		
			case 7:
		{
   
			P2=(P2&0x1f)|0xe0;
		  break;}
	}
	
	P2=(P2&0x1f);
}

void Initsystem()
{
   
	P0=0x00;
	Select573(5);
	P0=0xff;
	Select573(4);
}

void Timer0Init(void)		//1000微秒@11.0592MHz==1ms
{
   
	AUXR |= 0x80;		//定时器时钟1T模式
	TMOD &= 0xF0;		//设置定时器模式
	TL0 = 0xCD;		//设置定时初值
	TH0 = 0xD4;		//设置定时初值
	TF0 = 0;		//清除TF0标志
	TR0 = 1;		//定时器0开始计时
	
	ET0=1;
	EA=1;
}

void Display(unsigned char pos,unsigned char num)
{
   
	P0=0xff;
	Select573(7);
	P0=0x01<<pos;
	Select573(6);
	P0=SMG[num];
	Select573(7);
}


void DisplayAll()
{
   
	Display(5,pos5);
	Display(6,pos6);
	Display(7,pos7);
	P0=0xff;
	Select573(7);
}

void Timer0()	interrupt 1
{
   
	if(++scanpoint==10)//10ms 扫描一次
	{
   
		scanpoint=0;
	}

	if(number>99)
	{
   
	pos5=number/100;
	pos6=(number/10)%10;
	pos7=number%10;
	}
	
	if((number>9)&&(number<100))
	{
   
	pos5=10;
	pos6=(number/10)%10;
	pos7=number%10;
	}
	
	if(number<10)
	{
   
	pos5=10;
	pos6=10;
	pos7=