#include <reg51.h>
//
	sbit P1_0=P1^7;				//DIP-SW
//          ^    ^ 上面的值依照腳位更改
	sbit P3_5=P3^5;				//BUZZER
	sbit P3_3=P3^3;				//BTN_SW
	unsigned int t=(65536 - 11059000/(12*2*998));			//F=998 Hz
                 //  上面的公式要背         ^上面的值依照頻率改
	void delay(int);
//
main()
{
 	IE=0x84;
	TMOD=0x01;
	TCON=0x00;	
loop:
	if(P1_0==0)
	{
       P2=0xf0;   //1111 0000     P2.7~P2.4暗，P2.3~P2.0亮
	   delay(32);
       P2=0x0f;   //0000 1111     P2.7~P2.4亮，P2.3~P2.0暗
	   delay(32);            //延遲0.4秒，這裡的數值大約給32
       P2=0xf0;   //1111 0000
	   delay(32);
       P2=0x0f;   //0000 1111
	   delay(32);
       P2=0xf0;   //1111 0000
	   delay(32);
       P2=0x0f;   //0000 1111
	   delay(32);
       P2=0xf0;   //1111 0000
	   delay(32);
       P2=0x0f;   //0000 1111
	   delay(32);
       P2=0xf0;   //1111 0000
	   delay(32);
       P2=0x0f;   //0000 1111
	   delay(32);

	}
	else
	{
	P2=0XFF;
	}
goto loop;
}
//
void delay(int count)
  {
  int i,j;
  for(i=0;i<count;i++)       
     for(j=0;j<2000;j++);
  }

void EX1_int(void) interrupt 2 
{
 int i;            //以下程式是固定的，請背起來
 for(i=0;i<200;i++)
   {
      P3_5 = 1;
	  TH0 = t/256;
	  TL0 = t%256;
	  TR0 = 1;
	  while(TF0==0);
	  TF0 = 0;
      P3_5 = 0;
	  TH0 = t/256;
	  TL0 = t%256;
	  TR0 = 1;
	  while(TF0==0);
	  TF0 = 0;
   }
}