单片机制作“ 叮咚”门铃,AT89S51 DOORBELL

单片机制作“ 叮咚”门铃,AT89S51 DOORBELL

关键字：AT89S51,门铃电路

 

1．实验任务

当按下开关SP1，AT89S51单片机产生“叮咚”声从P1.0端口输出到LM386，经过放大之后送入喇叭。

2．电路原理图

 

 

3．系统板上硬件连线

（1．       把“单片机系统”区域中的P1.0端口用导线连接到“音频放大模块”区域中的SPK IN端口上；

（2．       在“音频放大模块”区域中的SPK OUT端口上接上一个8欧或者是16欧的喇叭；

（3．       把“单片机系统”区域中的P3.7/RD端口用导线连接到“独立式键盘”区域中的SP1端口上；

4．程序设计方法

（1．       我们用单片机实定时/计数器T0来产生700HZ和500HZ的频率，根据定时/计数器T0，我们取定时250us，因此，700HZ的频率要经过3次250us的定时，而500HZ的频率要经过4次250us的定时。

（2．       在设计过程，只有当按下SP1之后，才启动T0开始工作，当T0工作完毕，回到最初状态。

（3．       “叮”和“咚”声音各占用0.5秒，因此定时/计数器T0要完成0.5秒的定时，对于以250us为基准定时2000次才可以。

6．汇编源程序

T5HZ                  EQU 30H

T7HZ                  EQU 31H

T05SA                EQU 32H

T05SB                 EQU 33H

FLAG                 BIT 00H

STOP                  BIT 01H

SP1                      BIT P3.7

                            ORG 00H

                            LJMP START

                            ORG 0BH

                            LJMP INT_T0

START:               MOV TMOD,#02H

                            MOV TH0,#06H

                            MOV TL0,#06H

                            SETB ET0

                            SETB EA

NSP:                   JB SP1,NSP

                            LCALL DELY10MS

                            JB SP1,NSP

                            SETB TR0

                            MOV T5HZ,#00H

                            MOV T7HZ,#00H

                            MOV T05SA,#00H

                            MOV T05SB,#00H

                            CLR FLAG

                            CLR STOP                  

                            JNB STOP,$

                            LJMP NSP

DELY10MS:       MOV R6,#20

D1:                      MOV R7,#248

                            DJNZ R7,$

                            DJNZ R6,D1

                            RET

INT_T0:             INC T05SA

                            MOV A,T05SA

                            CJNE A,#100,NEXT

                            MOV T05SA,#00H

                            INC T05SB

                            MOV A,T05SB

                            CJNE A,#20,NEXT

                            MOV T05SB,#00H

                            JB FLAG,STP

                            CPL FLAG

                            LJMP NEXT

STP:                    SETB STOP

                            CLR TR0

                            LJMP DONE

NEXT:                JB FLAG,S5HZ

                            INC T7HZ

                            MOV A,T7HZ

                            CJNE A,#03H,DONE

                            MOV T7HZ,#00H

                            CPL P1.0

                            LJMP DONE

S5HZ:                 INC T5HZ

                            MOV A,T5HZ

                            CJNE A,#04H,DONE

                            MOV T5HZ,#00H

                            CPL P1.0

                            LJMP DONE

DONE:                RETI

                            END

 

7．C语言源程序

#include

unsigned char t5hz;

unsigned char t7hz;

unsigned int tcnt;

bit stop;

bit flag;

void main(void)

{

  unsigned char i,j;

  TMOD=0x02;

  TH0=0x06;

  TL0=0x06;

  ET0=1;

  EA=1;

  while(1)

    {

      if(P3_7==0)

        {

          for(i=10;i>0;i--)

          for(j=248;j>0;j--);

          if(P3_7==0)

            {

              t5hz=0;

              t7hz=0;

              tcnt=0;

              flag=0;

              stop=0;

              TR0=1;

              while(stop==0);

            }

        }

    }

}

void t0(void) interrupt 1 using 0

{

  tcnt++;

  if(tcnt==2000)

    {

      tcnt=0;

      if(flag==0)

        {

          flag=~flag;

        }

        else

          {

            stop=1;

            TR0=0;

          }

    }

  if(flag==0)

    {

      t7hz++;

      if(t7hz==3)

        {

          t7hz=0;

          P1_0=~P1_0;

        }

    }

    else

      {

        t5hz++;

        if(t5hz==4)

          {

            t5hz=0;

            P1_0=~P1_0;

          }

      }

}