转自《嵌入式Linux应用开发完全手册》 1. 先看电路图
2. 配置按键为输入，LED为输入 （1）通过crt0.S转入C程序 .text .global _start _start: ldr r0, =0x53000000 @ WATCHDOG寄存器地址 mov r1, #0x0 str r1, [r0] @ 写入0，禁止WATCHDOG，否则CPU会不断重启 ldr sp, =1024*4 @ 设置堆栈，注意：不能大于4K，因为可用的内存只有4K @ nand flash中的代码在复位后会移到内部ram中，此ram只有4K bl main @ 调用C程序中的main函数halt_loop: b halt_loop（2）key_led.c #define GPFCON  (*(volatile unsigned long *) 0x56000050) #define GPFDAT   (*(volatile unsigned long *) 0x56000054)
#define GPGCON (*(volatile unsigned long *) 0x56000060) #define GPGDAT   (*(volatile unsigned long *) 0x56000064)
#define GPF4_out (1<<(4*2)) #define GPF5_out (1<<(5*2)) #define GPF6_out (1<<(6*2))
#define GPF4_msk (3<<(4*2)) #define GPF5_msk (3<<(5*2)) #define GPF6_msk (3<<(6*2))
#define GPF0_in (0<<(0*2)) #define GPF2_in (0<<(2*2)) #define GPG3_in (0<<(3*2))
#define GPF0_msk (3<<(0*2)) #define GPF2_msk (3<<(2*2)) #define GPG3_msk (3<<(3*2))
int main() { unsigned long dwDat; GPFCON &= ~(GPF4_msk | GPF5_msk | GPF6_msk); GPFCON |= GPF4_out | GPF5_out | GPF_out;
GPFCON &= ~(GPF0_msk | GPF2_msk); GPFCPN |= GPF0_in | GPF2_in;
GPGCON &= ~GPG3_msk; GPGCON != GPG3_in;
while (1) { dwDat = GPFDAT; if (dwDat & (1<<0)) GPFDAT |= (1<<4); else GPFDAT &= ~(1<<4); if (dwDat & (1<<2)) GPFDAT |= (1<<5); else GPFDAT &= ~(1<<5);
dwDat = GPGDAT;
if (dwDat & (1<<3)) GPFDAT |= (1<<6); else GPFDAT &= ~(1<<6); } return 0; } 3. 总结 清0使用 &= ~ 置1使用 |=