51键盘显示程序自动化技术网-plc单片机微机.txt

51单片机键盘显示应用程序

                  51键盘显示程序 


                         
                        主程序: 
                        start:
                              call disp
                              lcall keyscan
                              cjne a,#0ffh,nex
                              sjmp start
                        nex:
                              mov 20h,a
                              sjmp start
                        ;显示函数,显示从20h开始的3个单元的内容
                        disp:
                              mov r0,#20h
                              mov r1,#1
                              mov r2,#01
                        lop: 
                              mov a,@r0
                              lcall displ
                              mov a,@r0
                              lcall disph
                              inc r0
                              djnz r1,lop
                              ret
                        disph:
                             swap a
                        displ:
                             anl a,#0fh
                             mov dptr,#tab
                             movc a,@a+dptr
                             mov dptr,#pb
                             movx @dptr,a
                             mov a,r2
                             mov dptr,#pa
                             movx @dptr,a
                             rl a
                             mov r2,a
                             lcall delay
                             clr a
                             movx @dptr,a
                             ret  
                          ;键盘扫描子程序
                        keyscan:
                            mov a,#0
                            mov dptr,#4f02
                            movx @dptr,a
                         
                            lcall testkey
                            jnz kn1
                            sjmp fret
                        kn1:
                            lcall getkey
                            mov r7,a
                            lcall aga
                            cjne r2,#0FFH,fret
                            lcall delay
                            lcall getkey
                            xrl a,r7
                            jnz fret
                        wait:
                            call testkey
                            jnz wait
                            mov a,r7
                            ret
                        fret:
                            mov a,#0FFH
                            ret
                         
                        ;测试是否有键按下 
                        testkey:
                            mov dptr,#4f01
                            clr a
                            movx @dptr,a
                            mov dptr,#4f03
                            movx a,@dptr
                            cpl a
                            anl a,#0fh
                            ret
                        ;延时
                        delay:
                            mov r0,#0
                            djnz r0,$
                            ret
                        ;取得按下键的键值
                        getkey:
                            mov r5,#8
                            mov r3,#0FEH
                        lop1: 
                            mov dptr,#4f01H
                            mov a,r3
                            movx @dptr,a
                         
                            ;mov b,a
                            rl a
                            mov r3,a
                            mov dptr,#4F03H
                            movx a,@dptr
                            anl a,#0fh
                            cjne a,#0fh,nex1
                        aga: 
                            djnz r5,lop1
                            mov r2,#0ffh
                            ret
                        nex1:
                            mov r1,a
                            mov a,#9
                            subb a,r5
                            rl a
                            rl a
                            mov r2,a
                            mov a,r1
                            mov r1,#4
                            cpl a
                        lop2: 
                            rrc a
                            jc exit
                            inc r2
                            djnz r1,lop2
                        exit:
                            mov a,r2
                            mov dptr,#keytable
                            movc a,@a+dptr
                            ret
                        ;键值表
                        keytable:
                           DB     00H,04H,08H,0CH
                           DB     10H,14H,18H,1CH
                           DB     01H,05H,09H,0DH
                           DB     11H,15H,19H,1DH
                           DB     02H,06H,0AH,0EH
                           DB     12H,16H,1AH,1EH
                           DB     03H,07H,0BH,0FH
                           DB     13H,17H,1BH,1FH 
                         ;8段码表
                        tab: