1．實(shí)驗(yàn)任務(wù)

如圖所示，AT89S51單片機(jī)的P1.0－P1.3接四個(gè)發(fā)光二極管L1－L4，P1.4－P1.7接了四個(gè)開(kāi)關(guān)K1－K4，編程將開(kāi)關(guān)的狀態(tài)反映到發(fā)光二極管上。（開(kāi)關(guān)閉合，對(duì)應(yīng)的燈亮，開(kāi)關(guān)斷開(kāi)，對(duì)應(yīng)的燈滅）。

2．電路原理圖

 

 

3．系統(tǒng)板上硬件連線

（1．       把“單片機(jī)系統(tǒng)”區(qū)域中的P1.0－P1.3用導(dǎo)線連接到“八路發(fā)光二極管指示模塊”區(qū)域中的L1－L4端口上；

（2．       把“單片機(jī)系統(tǒng)”區(qū)域中的P1.4－P1.7用導(dǎo)線連接到“四路撥動(dòng)開(kāi)關(guān)”區(qū)域中的K1－K4端口上；

4．  程序設(shè)計(jì)內(nèi)容

（1．       開(kāi)關(guān)狀態(tài)檢測(cè)

對(duì)于開(kāi)關(guān)狀態(tài)檢測(cè)，相對(duì)單片機(jī)來(lái)說(shuō)，是輸入關(guān)系，我們可輪流檢測(cè)每個(gè)開(kāi)關(guān)狀態(tài)，根據(jù)每個(gè)開(kāi)關(guān)的狀態(tài)讓相應(yīng)的發(fā)光二極管指示，可以采用JB P1.X，REL或JNB P1.X，REL指令來(lái)完成；也可以一次性檢測(cè)四路開(kāi)關(guān)狀態(tài)，然后讓其指示，可以采用MOVA，P1指令一次把P1端口的狀態(tài)全部讀入，然后取高4位的狀態(tài)來(lái)指示。

（2．       輸出控制

根據(jù)開(kāi)關(guān)的狀態(tài)，由發(fā)光二極管L1－L4來(lái)指示，我們可以用SETB P1.X和CLR P1.X指令來(lái)完成，也可以采用MOV P1，＃1111XXXXB方法一次指示。

5．程序框圖 (略)

6．方法一（匯編源程序）

                                      ORG 00H

START:                        MOV A,P1

                                      ANL A,#0F0H

                                      RR A

                                      RR A

                                      RR A

                                      RR A

                                      XOR A,#0F0H

                                      MOV P1,A

                                      SJMP START

                                      END

7．方法一（C語(yǔ)言源程序）

#include

unsigned char temp;

 

void main(void)

{

  while(1)

    {

      temp=P1>>4;

      temp=temp | 0xf0;

      P1=temp;

    }

}

8．方法二（匯編源程序）

                                      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

9．方法二（C語(yǔ)言源程序）

#include

 

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;

          }

    }

}