mini2440-按键控制LED

crt0.S

@******************************************************************************
@ File：crt0.S
@ 功能：通过它转入C程序
@******************************************************************************       

.text
.global _start
_start:
	LDR 	r0,=0x53000000		@ WATCHDOG寄存器地址
	MOV		r1,#0x00000000 

	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, 因为现在可用的内存只有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

key_led.c

#define GPBCON  *((volatile unsigned long *)0x56000010)
#define GPBDAT 	*((volatile unsigned long *)0x56000014)

#define GPGCON  *((volatile unsigned long *)0x56000060)
#define GPGDAT 	*((volatile unsigned long *)0x56000064)

/*
 * LED1,LED2,LED3对应GPB5、GPB6、GPB7
 */
#define GPB5_out 		(1<<(2*5))
#define GPB6_out 		(1<<(2*6))
#define GPB7_out		(1<<(2*7))

#define GPB5_msk	(3<<(2*5))
#define GPB6_msk	(3<<(2*6))
#define GPB7_msk	(3<<(2*7))

/*
 * k1,k2,k3对应GPG0、GPG3、GPG5
 */
#define GPG0_in		(0<<(2*0))
#define GPG3_in		(0<<(2*3))
#define GPG5_in		(0<<(2*5))

#define GPG0_msk	(3<<(2*0))
#define GPG3_msk	(3<<(2*3))
#define GPG5_msk	(3<<(2*5))

int main()
{
	unsigned long dwDat;
	 // LED1,LED2,LED3对应的3根引脚设为输出
	GPBCON &=~(GPB5_msk|GPB6_msk|GPB7_msk);
	GPBCON |= GPB5_out|GPB6_out|GPB7_out;
	// k1,k2,k3对应的2根引脚设为输入
	GPGCON &=~(GPG0_msk|GPG3_msk|GPG5_msk);
	GPGCON |= GPG0_in|GPG3_in|GPG5_in;
	//LEDn为1,not bright
	GPBDAT |=(1<<5)|(1<<6)|(1<<7);
	while(1)
	{
		dwDat= GPGDAT;// 读取GPG管脚电平状态
		if(dwDat & (1<<0))// k1没有按下
		{
			GPBDAT |=(1<<5);// LED1熄灭
		}
		else
		{
			GPBDAT &=~(1<<5);// LED1点亮
		}
		if(dwDat & (1<<3))
		{
			GPBDAT |=(1<<6);
		}
		else
		{
			GPBDAT &=~(1<<6);
		}

		if(dwDat & (1<<5))
		{
			GPBDAT |=(1<<7);
		}
		else
		{
			GPBDAT &=~(1<<7);
		}

	}

	return 0;
	
}

Makefile

CFLAGS 	:= -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -ffreestanding
ledon.bin:crt0.S key_led.c 
	arm-linux-gcc -g -c crt0.S -o crt0.o 
	arm-linux-gcc -g -c key_led.c  -o key_led.o 
	arm-linux-ld  -Ttext  0x00000000  crt0.o key_led.o  -o ledon_elf
	arm-linux-objcopy -O binary  -S ledon_elf ledon.bin
	arm-linux-objdump -D -m arm  ledon_elf > ledon.dis
clean:
	rm -rf  *.bin *elf *.o *.dis