12.21 汇编点亮STM32MP157小灯

.text 
.global _start
_start: 
    @时钟使能
    LDR r0,=0x50000A28
    LDR r1,[r0]
    ORR r1,r1,#(0x1<<4)
    ORR r1,r1,#(0x1<<5)
    ORR r1,r1,#(0x1<<1)
    STR r1,[r0]

    @配置GPIO模式
    LDR r0,=0x50006000
    LDR r1,[r0]
    BIC r1,r1,#(0x2<<20)
    ORR r1,r1,#(0x1<<20)
    BIC r1,r1,#(0x2<<16)
    ORR r1,r1,#(0x1<<16)
    STR r1,[r0]

    LDR r0,=0x50007000
    LDR r1,[r0]
    BIC r1,r1,#(0x2<<20)
    ORR r1,r1,#(0x1<<20)
    STR r1,[r0]


    @配置GPIO推挽输出模式
    LDR r0,=0x50006004
    LDR r1,[r0]
    BIC r1,r1,#(0x1<<10)
    BIC r1,r1,#(0x1<<8)
    STR r1,[r0]

    LDR r0,=0x50007004
    LDR r1,[r0]
    BIC r1,r1,#(0x1<<10)
    STR r1,[r0]


    @配置GPIO为低速输出
    LDR r0,=0x50006008
    LDR r1,[r0]
    BIC r1,r1,#(0x3<<20)
    BIC r1,r1,#(0x3<<16)
    STR r1,[r0]

    LDR r0,=0x50007008
    LDR r1,[r0]
    BIC r1,r1,#(0x3<<20)
    STR r1,[r0]


    @设置PE10和PE8为无上下拉电阻
    LDR r0,=0x5000600c
    LDR r1,[r0]
    BIC r1,r1,#(0x3<<20)
    BIC r1,r1,#(0x3<<16)
    STR r1,[r0]

    LDR r0,=0x5000700c
    LDR r1,[r0]
    BIC r1,r1,#(0x3<<20)
    STR r1,[r0]
    
loop:
    bl led_on
    bl delay
    bl led_off
    bl delay

    b loop
led_on:
    @设置小灯亮
    LDR r0,=0x50006014
    LDR r1,[r0]
    ORR r1,r1,#(0x1<<10)
    ORR r1,r1,#(0x1<<8)
    STR r1,[r0]

    LDR r0,=0x50007014
    LDR r1,[r0]
    ORR r1,r1,#(0x1<<10)
    STR r1,[r0]
    mov pc,lr

led_off:
    @设置小灯灭
    LDR r0,=0x50006014
    LDR r1,[r0]
    BIC r1,r1,#(0x1<<10)
    BIC r1,r1,#(0x1<<8)
    STR r1,[r0]

    LDR r0,=0x50007014
    LDR r1,[r0]
    BIC r1,r1,#(0x1<<10)
    STR r1,[r0]
    mov pc,lr

 delay:
    LDR  R3,=0x10000000
mm:
    cmp r3,#0
    subne r3,r3,#1
    bne mm
    mov pc,lr

.end