/*******************************************************************************
*                                                                              *
*    File       : uP51s002.asm                                                 *
*    Date       : 2004-9-5                                                     *
*    Version    : 1.0                                                          *
*                                                                              *
*    Author     : kevin           kevin@dz51.com                               *
*    Company    : Http://www.dz51.com                                          *
*                                                                              *
********************************************************************************
*    Descriptoon:                                                              *
*                報警聲程序                                                    *
*                                                                              *
*                                                                              *
*                                                                              *
*                                                                              *
*                                                                              *
*******************************************************************************/
#include <reg51.h>
#include <intrins.h>

sbit	SPK = P3^7;

unsigned char frq; 

void delayms(unsigned char ms);

main()
{
	TMOD = 0x01;
	frq = 0x00;
	TH0 = 0x00;
	TL0 = 0xff;	
	TR0 = 1;
	IE = 0x82;
	
	while(1)
	{
		frq++;
		delayms(1);
	}
}

void timer0() interrupt 1 using 1
{
	TH0 = 0xfe;
	TL0 = frq;
	SPK = ~SPK;	
}

void delayms(unsigned char ms)	
// 延時子程序
{						
	unsigned char i;
	while(ms--)
	{
		for(i = 0; i < 120; i++);
	}
}