S3C2440 gpio + main

相关文章：http://blog.csdn.net/zhangxuechao_/article/details/77990854

举例
start.S

.globl _start
_start:

/* 关看门狗 */
/* 往WTCON(0x53000000)写0 */
    ldr r0, =0x53000000
    mov r1, #0
    str r1, [r0] @ str, store, 

    /* 设置栈大小，不能大于4k，因为片内SRAM只有4k */
    ldr sp, =1024*4

    bl main

halt:
    b halt  

main.c

#define GPFCON (*(volatile unsigned int*)0x56000050)
#define GPFDAT (*(volatile unsigned int*)0x56000054)

int main()
{
    GPFCON |= (1 << 8);
    GPFDAT &= (0 << 4);

    return 0;
}