原创 17．99秒马表设计

1．             实验任务<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

（1．       开始时，显示“00”，第1次按下SP1后就开始计时。

（2．       第2次按SP1后，计时停止。

（3．       第3次按SP1后，计时归零。

5．           汇编源程序

TCNTA            EQU 30H

TCNTB           EQU 31H

SEC       EQU 32H

KEYCNT          EQU 33H

SP1       BIT P3.5

        ORG 00H

        LJMP START

           ORG 0BH

        LJMP INT_T0

START:    MOV KEYCNT,#00H

        MOV SEC,#00H

        MOV A,SEC

        MOV B,#10

        DIV AB

        MOV DPTR,#TABLE

        MOVC A,@A+DPTR

        MOV P0,A

        MOV A,B

        MOV DPTR,#TABLE

        MOVC A,@A+DPTR

        MOV P2,A

        MOV TMOD,#02H

        SETB ET0

        SETB EA

WT:       JB SP1,WT

        LCALL DELY10MS

        JB SP1,WT

        INC KEYCNT

        MOV A,KEYCNT

        CJNE A,#01H,KN1

        SETB TR0

        MOV TH0,#06H

        MOV TL0,#06H

        MOV TCNTA,#00H

        MOV TCNTB,#00H

        LJMP DKN

KN1:      CJNE A,#02H,KN2

        CLR TR0

        LJMP DKN

KN2:      CJNE A,#03H,DKN

        MOV SEC,#00H

        MOV A,SEC

        MOV B,#10

           DIV AB

        MOV DPTR,#TABLE

        MOVC A,@A+DPTR

        MOV P0,A

        MOV A,B

        MOV DPTR,#TABLE

        MOVC A,@A+DPTR

        MOV P2,A

        MOV KEYCNT,#00H

DKN:    JNB SP1,$

        LJMP WT

DELY10MS:

           MOV R6,#20

D1:        MOV R7,#248

        DJNZ R7,$

        DJNZ R6,D1

        RET

INT_T0:

        INC TCNTA

        MOV A,TCNTA

        CJNE A,#100,NEXT

        MOV TCNTA,#00H

        INC TCNTB

        MOV A,TCNTB

        CJNE A,#4,NEXT

        MOV TCNTB,#00H

        INC SEC

        MOV A,SEC

        CJNE A,#100,DONE

        MOV SEC,#00H

DONE:             MOV A,SEC

        MOV B,#10

        DIV AB

        MOV DPTR,#TABLE

        MOVC A,@A+DPTR

        MOV P0,A

        MOV A,B

        MOV DPTR,#TABLE

        MOVC A,@A+DPTR

        MOV P2,A

NEXT:   RETI

TABLE:  DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH

        END

6．           C语言源程序

#include <AT89X51.H>

unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,

                               0x66,0x6d,0x7d,0x07,

                               0x7f,0x6f,0x77,0x7c,

                               0x39,0x5e,0x79,0x71,0x00};

unsigned char second;

unsigned char keycnt;

unsigned int tcnt;

void main(void)

{

  unsigned char i,j;

  TMOD=0x02;

  ET0=1;

  EA=1;

  second=0;

  P0=dispcode[second/10];

  P2=dispcode[second%10];

  while(1)

    {

      if(P3_5==0)

        {

          for(i=20;i>0;i--)

          for(j=248;j>0;j--);

          if(P3_5==0)

            {

              keycnt++;

              switch(keycnt)

                {

                  case 1:

                    TH0=0x06;

                    TL0=0x06;

                    TR0=1;

                    break;

                  case 2:

                    TR0=0;

                    break;

                  case 3:

                    keycnt=0;

                    second=0;

                    P0=dispcode[second/10];

                    P2=dispcode[second%10];

                    break;

                }

              while(P3_5==0);

            }

        }

    }

}

void t0(void) interrupt 1 using 0

{

  tcnt++;

  if(tcnt==4000)

    {

      tcnt=0;

      second++;

      if(second==100)

        {

          second=0;

        }

      P0=dispcode[second/10];

      P2=dispcode[second%10];

    }

}