原创 6．报警产生器

1． 实验任务<?XML:NAMESPACE PREFIX = O />

用P1.0输出1KHz和500Hz的音频信号驱动扬声器，作报警信号，要求1KHz信号响100ms，500Hz信号响200ms,交替进行，P1.7接一开关进行控制，当开关合上响报警信号，当开关断开告警信号停止，编出程序。

2． 电路原理图

<?XML:NAMESPACE PREFIX = V />

图1

图2

3．程序设计内容

（1．       信号产生的方法

500Hz信号周期为2ms，信号电平为每1ms变反1次，1KHz的信号周期为1ms，信号电平每500us变反1次；

4． 程序框图

图3

5． 汇编源程序

FLAG                           BIT 00H                                       ;用FLAG代替地址00H

                                      ORG 00H

START:                        JB P1.7,START

                         ;P1.7为1时跳转

                                      JNB FLAG,NEXT

                     ;FLAG(00H)为0时跳转

                                      MOV R2,#200

DV:                               CPL P1.0

                                     ;P1.0取反

                                      LCALL DELY500

                       ;跳转到DELY500延时

                                      LCALL DELY500

                                      DJNZ R2,DV

                              ;R2减1,不为0时转移到DV

                                      CPL FLAG

NEXT:                         MOV R2,#200

DV1:                   CPL P1.0

                                      LCALL DELY500

                                      DJNZ R2,DV1

                                      CPL FLAG

                                      SJMP START

DELY500:           MOV R7,#250

LOOP:                         NOP

                                       ;空操作，占1个机器周期

                                      DJNZ R7,LOOP

                                      RET

                                      END

6． C语言源程序

#include

#include

bit flag;

unsigned char count;

void dely500(void)

{

  unsigned char i;

  for(i=250;i>0;i--)

    {

      _nop_();

    }

}

void main(void)

{

  while(1)

    {

      if(P1_7==0)

        {

          for(count=200;count>0;count--)

            {

              P1_0=~P1_0;

              dely500();

            }

          for(count=200;count>0;count--)

            {

              P1_0=~P1_0;

              dely500();

              dely500();

            }

        }

    }

}

7． 仿真文件