原创 14．4×4矩阵式键盘识别技术

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

用AT89S51的并行口P1接4×4矩阵键盘，以P3.0－P3.3作输入线，以P3.4－P3.7作输出线；在数码管上显示每个按键的“0－F”序号。对应的按键的序号排列如图所示

2． 硬件电路原理图

3．  程序设计内容

（1．       4×4矩阵键盘识别处理

（2．       每个按键有它的行值和列值　，行值和列值的组合就是识别这个按键的编码。矩阵的行线和列线分别通过两并行接口和CPU通信。每个按键的状态同样需变成数字量“0”和“1”，开关的一端（列线）通过电阻接V_CC，而接地是通过程序输出数字“0”实现的。键盘处理程序的任务是：确定有无键按下，判断哪一个键按下，键的功能是什么；还要消除按键在闭合或断开时的抖动。两个并行口中，一个输出扫描码，使按键逐行动态接地，另一个并行口输入按键状态，由行扫描值和回馈信号共同形成键编码而识别按键，通过软件查表，查出该键的功能。

4、实现程序

1． 汇编源程序

KEYBUF    EQU 30H

            ORG 00H

START:      MOV KEYBUF,#2

WAIT:  

            MOV P3,#0FFH

            CLR P3.4

            MOV A,P3

            ANL A,#0FH 

            XRL A,#0FH

            JZ NOKEY1

            LCALL DELY10MS

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY1

            MOV A,P3

            ANL A,#0FH

            CJNE A,#0EH,NK1

            MOV KEYBUF,#0

            LJMP DK1

NK1:        CJNE A,#0DH,NK2

            MOV KEYBUF,#1

            LJMP DK1

NK2:        CJNE A,#0BH,NK3

            MOV KEYBUF,#2

            LJMP DK1

NK3:        CJNE A,#07H,NK4

            MOV KEYBUF,#3

            LJMP DK1

NK4:        NOP

DK1:   

            MOV A,KEYBUF

            MOV DPTR,#TABLE

            MOVC A,@A+DPTR

            MOV P0,A

DK1A:       MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JNZ DK1A

NOKEY1:

            MOV P3,#0FFH

            CLR P3.5

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY2

            LCALL DELY10MS

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY2

            MOV A,P3

            ANL A,#0FH

            CJNE A,#0EH,NK5

            MOV KEYBUF,#4

            LJMP DK2

NK5:        CJNE A,#0DH,NK6

            MOV KEYBUF,#5

            LJMP DK2

NK6:        CJNE A,#0BH,NK7

            MOV KEYBUF,#6

            LJMP DK2

NK7:        CJNE A,#07H,NK8

            MOV KEYBUF,#7

            LJMP DK2

NK8:        NOP

DK2:   

            MOV A,KEYBUF

            MOV DPTR,#TABLE

            MOVC A,@A+DPTR

            MOV P0,A

DK2A:       MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JNZ DK2A

NOKEY2:

            MOV P3,#0FFH

            CLR P3.6

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY3

            LCALL DELY10MS

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY3

            MOV A,P3

            ANL A,#0FH

            CJNE A,#0EH,NK9

            MOV KEYBUF,#8

            LJMP DK3

NK9:        CJNE A,#0DH,NK10

            MOV KEYBUF,#9

            LJMP DK3

NK10:       CJNE A,#0BH,NK11

            MOV KEYBUF,#10

            LJMP DK3

NK11:       CJNE A,#07H,NK12

            MOV KEYBUF,#11

            LJMP DK3

NK12:       NOP

DK3:

            MOV A,KEYBUF

            MOV DPTR,#TABLE

            MOVC A,@A+DPTR

            MOV P0,A

DK3A:       MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JNZ DK3A

NOKEY3:

            MOV P3,#0FFH

            CLR P3.7

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY4

            LCALL DELY10MS

            MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JZ NOKEY4

            MOV A,P3

            ANL A,#0FH

            CJNE A,#0EH,NK13

            MOV KEYBUF,#12

            LJMP DK4

NK13:       CJNE A,#0DH,NK14

            MOV KEYBUF,#13

            LJMP DK4

NK14:       CJNE A,#0BH,NK15

            MOV KEYBUF,#14

            LJMP DK4

NK15:       CJNE A,#07H,NK16

            MOV KEYBUF,#15

            LJMP DK4

NK16:       NOP

DK4:   

            MOV A,KEYBUF

            MOV DPTR,#TABLE

            MOVC A,@A+DPTR

            MOV P0,A

DK4A:       MOV A,P3

            ANL A,#0FH

            XRL A,#0FH

            JNZ DK4A

NOKEY4:

            LJMP WAIT

DELY10MS:

            MOV R6,#10

D1:         MOV R7,#248

            DJNZ R7,$

            DJNZ R6,D1

            RET

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

            DB 7FH,6FH,77H,7CH,39H,5EH,79H,71H

            END

2． C语言源程序

  #include <AT89X51.H>

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

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

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

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

unsigned char temp;

unsigned char key;

unsigned char i,j;

void main(void)

{

  while(1)

    {

      P3=0xff;

      P3_4=0;

      temp=P3;

      temp=temp & 0x0f;

      if (temp!=0x0f)

        {

          for(i=50;i>0;i--)

          for(j=200;j>0;j--);

          temp=P3;

          temp=temp & 0x0f;

          if (temp!=0x0f)

            {

              temp=P3;

              temp=temp & 0x0f;             

              switch(temp)

                {

                  case 0x0e:

                    key=0;

                    break;

                  case 0x0d:

                    key=1;

                    break;

                  case 0x0b:

                    key=2;

                    break;

                  case 0x07:

                    key=3;

                    break;

                }

              temp=P3;

              P0=table[key];

              temp=temp & 0x0f;             

              while(temp!=0x0f)

                {

                  temp=P3;

                  temp=temp & 0x0f;             

                }

            }

        }

      P3=0xff;

      P3_5=0;

      temp=P3;

      temp=temp & 0x0f;

      if (temp!=0x0f)

        {

          for(i=50;i>0;i--)

          for(j=200;j>0;j--);

          temp=P3;

          temp=temp & 0x0f;

          if (temp!=0x0f)

            {

              temp=P3;

              temp=temp & 0x0f;             

              switch(temp)

                {

                  case 0x0e:

                    key=4;

                    break;

                  case 0x0d:

                    key=5;

                    break;

                  case 0x0b:

                    key=6;

                    break;

                  case 0x07:

                    key=7;

                    break;

                }

              temp=P3;

              P0=table[key];

              temp=temp & 0x0f;             

              while(temp!=0x0f)

                {

                  temp=P3;

                  temp=temp & 0x0f;             

                }

            }

        }

      P3=0xff;

      P3_6=0;

      temp=P3;

      temp=temp & 0x0f;

      if (temp!=0x0f)

        {

          for(i=50;i>0;i--)

          for(j=200;j>0;j--);

          temp=P3;

          temp=temp & 0x0f;

          if (temp!=0x0f)

            {

              temp=P3;

              temp=temp & 0x0f;             

              switch(temp)

                {

                  case 0x0e:

                    key=8;

                    break;

                  case 0x0d:

                    key=9;

                    break;

                  case 0x0b:

                    key=10;

                    break;

                  case 0x07:

                    key=11;

                    break;

                }

              temp=P3;

              P0=table[key];

              temp=temp & 0x0f;              

              while(temp!=0x0f)

                {

                  temp=P3;

                  temp=temp & 0x0f;             

                }

            }

        }

      P3=0xff;

      P3_7=0;

      temp=P3;

      temp=temp & 0x0f;

      if (temp!=0x0f)

        {

          for(i=50;i>0;i--)

          for(j=200;j>0;j--);

          temp=P3;

          temp=temp & 0x0f;

          if (temp!=0x0f)

            {

              temp=P3;

              temp=temp & 0x0f;             

              switch(temp)

                {

                  case 0x0e:

                    key=12;

                    break;

                  case 0x0d:

                    key=13;

                    break;

                  case 0x0b:

                    key=14;

                    break;

                  case 0x07:

                    key=15;

                    break;

                }

              temp=P3;

              P0=table[key];

              temp=temp & 0x0f;             

              while(temp!=0x0f)

                {

                  temp=P3;

                  temp=temp & 0x0f;             

                }

            }

        }

    }

}