请帮忙看一下这个程序，为什么LED常亮不闪呢 - 嵌入式开发

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请帮忙看一下这个程序，为什么LED常亮不闪呢

.text
.global _start
_start:
        ldr r0,=0x56000050

        mov r1,#0x00000015

        str r1,[r0]

        ldr r0,=0x56000054

        mov r1,#0x00000000
16
17         str r1,[r0]
18
19         mov r4,#134217728
20
21 @set cricle program
22
23                                 @close led
24 loop:
25         bl dely
26
27         ldr r0,=0x56000054
28
29         mov r1,#0x000000ff
30
31         str r1,[r0]
32
33                                 @open led
34         bl dely
35
36         ldr r0,=0x56000054
37
38         mov r1,#0x00000000
39
40         bl dely
41
42         b loop
43
44
45 dely:
46
47         sub r2,r2,#1
48
49         cmp r2,#0
50
51         bne dely

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第 2 楼

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.text
.global _start
_start:
        ldr r0,=0x56000050

        mov r1,#0x00000015

        str r1,[r0]

        ldr r0,=0x56000054

        mov r1,#0x00000000
16
17         str r1,[r0]
18
19         mov r4,#134217728
20
21 @set cricle program
22
23                                 @close led
24 loop:
25         bl dely
26
27         ldr r0,=0x56000054
28
29         mov r1,#0x000000ff
30
31         str r1,[r0]
32
33                                 @open led
34         bl dely
35
36         ldr r0,=0x56000054
37
38         mov r1,#0x00000000
39
40         bl dely
41
42         b loop
43
44
45 dely:
46
47         sub r4,r4,#1
48
49         cmp r4,#0
50
51         bne dely

第 3 楼

得分:0

没有人顶还是我自己顶吧，终于改过来了

以下是引用jianghong_02在2014-3-18 10:48:09的发言：

.text
.global _start
_start:
        ldr r0,=0x56000050

        mov r1,#0x00000015

        str r1,[r0]

        ldr r0,=0x56000054

        mov r1,#0x00000000
16
17         str r1,[r0]
18
19         mov r4,#134217728
20
21 @set cricle program
22
23                                 @close led
24 loop:
25         bl dely
26
27         ldr r0,=0x56000054
28
29         mov r1,#0x000000ff
30
31         str r1,[r0]
32
33                                 @open led
34         bl dely
35
36         ldr r0,=0x56000054
37
38         mov r1,#0x00000000
39
40         bl dely
41
42         b loop
43
44
45 dely:
46
47         sub r4,r4,#1
48
49         cmp r4,#0
50
51         bne dely

这是修改后能正常运行的程序
.text
.global _start
_start:

        ldr r0,=0x56000050

        mov r1,#0x00000001

        str r1,[r0]

        ldr r0,=0x56000054

        mov r1,#0x00000000

        str r1,[r0]

@set cricle program

                                @close led
loop:
        mov r4,#134217728

        bl dely

        ldr r0,=0x56000054

        mov r1,#0x000000ff

        str r1,[r0]

                                @open led
        mov r4,#134217728

        bl dely

        ldr r0,=0x56000054

        mov r1,#0x00000000

        str r1,[r0]

        b loop

dely:
        sub r4,r4,#1

        cmp r4,#0

        bne dely

        mov pc,lr