at89s51을 이용한 스피커 제어(전화벨소리)

#include<reg51.h>

sbit speaker = P2^0;

void delay(unsigned int i)
{
 while(i--);
}

void main(void)
{
 unsigned char j,k;
 while(1)
 {
  for(k=1;k<=20;k++)
  {
   for(j=1;j<=12;j++)
   {
    speaker = 1;
    delay(0x5d);
    speaker = 0;
    delay(0x5d);
   }
   for(j=1;j<=8;j++)
   {
    speaker = 1;
    delay(0x8c);
    speaker = 0;
    delay(0x8c); 
   }
  }
  for(k=0;k<4;k++)delay(0xb100);
 }
}