1 DAT_74164 BIT P0.6
2 CLK_74164 BIT P0.7
3
4 org 0000H
5 jmp MAIN
6
7 ;*******************************************
8 org 0030H ;Start program from 0030H
9 MAIN:
10 mov P0,#0FFH ；四个端口初始化，关闭外围
11 mov P1,#0FFH
12 mov P2,#0FFH
13 mov P3,#0FFH
14
15 MAIN_LOOP:
16 mov P0,#11111110B ;The first to show 1，位选
17 mov a,#0F9H ；段选，给a设一个F9：1111 1001，共阳0有效
18 call sendTo74164 ；约等于60微秒
19 call MIN_DELAY ；约等于10000微秒
20
21 mov P0,#11111101B ;The second to show 2
22 mov a,#10100100B
23 call sendTo74164
24 call MIN_DELAY
25
26 mov P0,#11111011B ;The third to show 3
27 mov a,#10110000B
28 call sendTo74164
29 call MIN_DELAY
30
31 jmp MAIN_LOOP
32
33 ret
34 ;*******************************************
35 ;Send data of A to chip 74LS164
36 sendTo74164:
37 push 07h
38 push acc
39
40 mov r7,#08 ;send 8 bits
41 SEND164_LOOP:
42 clr CLK_74164 ;clear clock-line for reading data
43 rlc a
44 mov DAT_74164,c ;move data-bit to data-line
45 setb CLK_74164 ;send data to 74164
46 djnz r7,SEND164_LOOP
47
48 pop acc
49 pop 07h
50 ret
51 ;*******************************************
52 ;Dealy for a interval
53 DELAY:
54 mov r5,#20H
55 DELAY_2:
56 mov R6,#0FFH
57 DELAY_1:
58
59 mov R7,#0FFH
60 DELAY_0:
61 nop
62 nop
63 djnz R7,DELAY_0
64
65 djnz R6,DELAY_1
66
67 djnz R5,DELAY_2
68
69 ret
70 ;*******************************************
71 ;Dealy for a interval
72 MIN_DELAY: （内循环1ms）
73 mov R6,#8
74 DELAY_02:
75 mov R7,#250
76 DELAY_01:
77 nop
78 nop
79 djnz R7,DELAY_01
80 djnz R6,DELAY_02
81 ret
82 ;*******************************************
83 END
