使用C汇编

#define WTDCON 0xE2700000

#define SVC_STACK 0xD0037D80

.global _start

_start:

ldr r0, =WTDCON //watchdog timer 控制寄存器地址写入r0寄存器

ldr r1, =0x0 //赋值0

str r1, [r0] //寻址，写0关闭watchdog

ldr sp, = SVC_STACK //设置c调用栈地址

bl  led_blink

b . //死循环

//c源程序

#define GPJ0CON 0xE0200240

#define GPJ0DAT  0xE0200244

#define rGPJ0CON *((volatile unsigned int *)GPJ0CON)  //通过宏定义寄存器内存地址所代表的值

#define rGPJ0DAT  *((volatile unsigned int *)GPJ0DAT)

void wait1s(void);

void led_blink(){

rGPJ0CON = 0x11111111;

while(1){

rGPJ0DAT = ((0<<3)|(0<<4)|(0<<5));  //3,4,5位写0

wait1s();

rGPJ0DAT = ((1<<3)|(1<<4)|(1<<5));  //3,4,5位写1

wait1s();

}

}

void wait1s(void){

volatile unsigned int i = 10000000;

while(i--);  //循环至0结束

}