51的单片机的定时器程序，大神看看哪里错了。蜂鸣器不响，LED正常

#include<reg51.h> #include<intrins.h> #define GPIO_LED P2unsigned char time;void Delay10ms(unsigned int c);sbit deep=P1^5;void timer ();void fasheng(); void main () { time=0; P2=0x01; timer(); while(1) { Delay10ms(100); GPIO_LED=_crol_(GPIO_LED,1); if(time==20) { fasheng(); time=0; } } } void timer () { TMOD=0x01; TH0=0x3C; TL0=0xB0; EA=1; ET0=1; TR0=1; }void timerr() interrupt 0{ TH0=0x3C; TL0=0xB0; time++;}void fasheng(){ unsigned char i,j; for(j=700;j>0;j--) { deep=!deep; for(i=0;i<100;i++); } }void Delay10ms(unsigned int c) //误差 0us{ unsigned char a,b; for(;c>0;c--) for(b=38;b>0;b--) for(a=130;a>0;a--);}