原创 3、多路开关状态指示

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

如图4.3.1所示，AT89S51单片机的P1.0－P1.3接四个发光二极管L1－L4，P1.4－P1.7接了四个开关K1－K4，编程将开关的状态反映到发光二极管上。（开关闭合，对应的灯亮，开关断开，对应的灯灭）。

2． 电路原理图

3、程序实现

1． 方法一（汇编源程序）

                                      ORG 00H

START:                        MOV A,P1         ；

                                      RR A

                                      RR A

                                      RR A

                                      RR A

                                      ORL A,#0F0H

                                      MOV P1,A

                                      SJMP START

                                      END

2． 方法一（C语言源程序）

#include <AT89X51.H>

unsigned char temp;

void main(void)

{

  while(1)

    {

      temp=P1>>4;        //P1.76543210=0000+四个开关状态

      temp=temp | 0xf0; //P1.76543210=1111+四个开关状态

      P1=temp;

    }

}

3． 方法二（汇编源程序）

                                      ORG 00H

START:                         JB P1.4,NEXT1

                                      CLR P1.0

                                      SJMP NEX1

NEXT1:                       SETB P1.0

NEX1:                          JB P1.5,NEXT2

                                      CLR P1.1

                                      SJMP NEX2

NEXT2:                       SETB P1.1

NEX2:                          JB P1.6,NEXT3

                                      CLR P1.2

                                      SJMP NEX3

NEXT3:                       SETB P1.2

NEX3:                          JB P1.7,NEXT4

                                      CLR P1.3

                                      SJMP NEX4

NEXT4:                       SETB P1.3

NEX4:                          SJMP START

                                      END

4． 方法二（C语言源程序）

#include <AT89X51.H>

void main(void)

{

  while(1)

    {

      if(P1_4==0)

        {

          P1_0=0;

        }

        else

          {

            P1_0=1;

          }

      if(P1_5==0)

        {

          P1_1=0;

        }

        else

          {

            P1_1=1;

          }

      if(P1_6==0)

        {

          P1_2=0;

        }

        else

          {

            P1_2=1;

          }

      if(P1_7==0)

        {

          P1_3=0;

        }

        else

          {

            P1_3=1;

          }

    }

}

4、总结

  多个LED和多个开关在同一个IO口上，最简便的方法是通过左右移位、与或操作来实现。汇编和C语言编程思想是相同的