通过加减键设置数字0～9

  1     CURR_NUM    EQU    30H　　　　　　　　　　；定义一个变量EQU
  2 
  3     DAT_74164    bit    P0.6  　　　　　　　　；3～10行：属于头文件，显示定义硬件资源与硬件引脚
  4     CLK_74164    bit    P0.7
  5 
  6     KEY_COMMON    bit    P3.2
  7     KEY_1        bit    p0.5
  8     KEY_2        bit    p0.4
  9 
 10     DIG_6        bit    p0.0
 11 
 12     org    0000H        
 13     jmp    MAIN
 14 
 15 ;*******************************************    
 16     org    0030H        ;Start program from 0030H        
 17 MAIN:
 18     mov    P0,#0FFH    ;Initialize the port    
 19     mov    P1,#0FFH    
 20     mov    P2,#0FFH    
 21     mov    P3,#0FFH
 22     
 23     mov    CURR_NUM,#00H    ;Initilize the var，给变量赋值0
 24     clr    KEY_COMMON    ;Clear the common line，公共端清零
 25 
 26 MAIN_LOOP:
 27     jb    KEY_2,LAB_KEY_1    ;Wait for key down,ADD
 28     call    DELAY
 29     call    NUM_ADD
 30     jmp    NEXT_LOOP
 31     
 32 LAB_KEY_1:
 33     jb    KEY_1,NEXT_LOOP    ;Wait for key down,SUB
 34     call    DELAY
 35     call    NUM_SUB
 36     jmp    NEXT_LOOP    
 37 
 38 NEXT_LOOP:
 39     call    DISPLAY_NUM
 40     call    DELAY_DISP
 41     jmp    MAIN_LOOP
 42 
 43     ret
 44 ;****************************************************
 45 DISPLAY_NUM:
 46     ;Get the code of led
 47     mov    a,CURR_NUM
 48     mov    dptr,#TAB_LED　　　　　　；48，49行查断码
 49     movc    a,@a+dptr
 50 
 51     ;Display the number
 52     call    sendTo74164
 53     clr    DIG_6    
 54         
 55     ret
 56 ;*******************************************
 57 ;Send data of A to chip 74LS164
 58 sendTo74164:
 59     push    07h
 60     push    acc
 61 
 62     mov    r7,#08        ;send 8 bits      
 63 SEND164_LOOP:
 64     clr    CLK_74164    ;clear clock-line for reading data
 65     rlc    a
 66     mov    DAT_74164,c    ;move data-bit to data-line    
 67     setb    CLK_74164    ;send data to 74164
 68     djnz    r7,SEND164_LOOP
 69     clr    CLK_74164    ;clear clock-line for reading data
 70         
 71     pop    acc
 72     pop    07h
 73     ret
 74 ;****************************************************
 75 NUM_ADD:
 76     ;Get next value
 77     mov    a,CURR_NUM　　　　　　　　　　；当前变量赋给a
 78     mov    dptr,#TAB_NEXT　　　　　　　　；表中的内容加载到指针
 79     movc    a,@a+dptr　　　　　　　　　　；查表

 80     mov    CURR_NUM,a　　　　　　　　　　；把查表查出来的值赋给a
 81     
 82     ret
 83 ;****************************************************
 84 NUM_SUB:
 85     ;Get previos value
 86     mov    a,CURR_NUM
 87     mov    dptr,#TAB_PRE
 88     movc    a,@a+dptr
 89     mov    CURR_NUM,a
 90     
 91     ret
 92 ;****************************************************
 93 DELAY:
 94     mov    r7,#200
 95 DELAY_LOOP:
 96     mov    r6,#200
 97     djnz    r6,$
 98     mov    r6,#200
 99     djnz    r6,$
100 
101     djnz    r7,DELAY_LOOP
102     ret
103 ;****************************************************
104 DELAY_DISP:
105     mov    r7,#10
106 DELAY_DISP_LOOP:
107     mov    r6,#200
108     djnz    r6,$
109     mov    r6,#200
110     djnz    r6,$
111 
112     djnz    r7,DELAY_DISP_LOOP
113     ret
114 ;****************************************************
115 ;****************************************************
116 ;LED code
117 TAB_LED:    
118     DB    0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H
119 ;===================================================
120 ;For sub
121 TAB_PRE:    
122     DB    09H,00H,01H,02H,03H,04H,05H,06H,07H,08H
123 ;===================================================
124 ;For add
125 TAB_NEXT:    
126     DB    01H,02H,03H,04H,05H,06H,07H,08H,09H,00H
127 ;****************************************************
128     END