Question

89C52单片机发出警笛声程序

要能发出警笛声的程序 不要音乐盒的 谢谢了~

Answer 1

#include <reg51.h>#include <intrins.h> sbit SPK = P3^4; unsigned char frq; void delayms(unsigned char ms) // 延时子程序{ unsigned char i; while(ms--) { for(i = 0; i < 120; i++); }} void timer0() interrupt 1 using 1{ TH0 = 0xfe; TL0 = frq; SPK = ~SPK; } main(){ TMOD = 0x01; frq = 0x00; TH0 = 0x00; TL0 = 0xff; TR0 = 1; IE = 0x82; while(1) { frq++; delayms(1); //改变此处可以改变报警声的节奏长度 }}

Answer 2

#include <reg52.h>
sbit SPK = P1^0;

unsigned char frq;
void delayms(unsigned char ms) // 延时子程序
{
unsigned char i;
while(ms--) for(i = 0; i < 120; i++);
}
void timer0() interrupt 1
{
TH0 = 0xfe;
TL0 = frq;
SPK = ~SPK;
}
main()
{
TMOD = 0x01;
frq = 0x00;
TH0 = 0xfe;
TL0 = 0;
TR0 = 1;
IE = 0x82;
while(1)
{ frq++;
delayms(1);
}
}

Answer 3

flag bit 00h
org 0h
ljmp start
org 30
start: jb p3.7,start
jnb flag,next mov r2,#200
sp0: cpl p3.0
lcall delay
lcall delay
djnz r2,sp0
cpl flagnext: mov r2,#200
sp1: cpl p3.0
lcall delay
djnz r2,sp1
cpl flag
sjmp start

delay: mov r7,#250
loop: nop
djnz r7,loop
ret
end