我的开发板是MINI2440,在使用VIVI的a命令将程序下到nand flash成功后,下电从nandflash启动,开发板按程序按键,程序不动。
将CRT0.S中的关闭看门狗0x53000000改为0x56000010后,再用同样方法下到nand flash成功后,下电从nandflash启动,程序正常。
按道理应该是CRT0.S中的关闭看门狗0x53000000是正确的,希望得到解答。谢谢
韦东山程序如下:
@******************************************************************************
@ 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, #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 GPGCON (*(volatile unsigned long *)0x56000060)
#define GPGDAT (*(volatile unsigned long *)0x56000064)
#define GPBCON (*(volatile unsigned long *)0x56000010)
#define GPBDAT (*(volatile unsigned long *)0x56000014)
/*
* LED1,LED2,LED4对应GPB5、GPB6、GPB7、GPB8
*/
#define GPB5_out (1<<(5*2))
#define GPB6_out (1<<(6*2))
#define GPB7_out (1<<(7*2))
#define GPB8_out (1<<(8*2))
#define GPB5_msk (3<<(5*2))
#define GPB6_msk (3<<(6*2))
#define GPB7_msk (3<<(7*2))
#define GPB8_msk (3<<(8*2))
/*
* K1,K2,K3,K4对应GPG0,GPG3,GPG5,GPG6
*/
#define GPG0_in (0<<(0*2))
#define GPG3_in (0<<(3*2))
#define GPG5_in (0<<(5*2))
#define GPG6_in (0<<(6*2))
#define GPG0_msk (3<<(0*2))
#define GPG3_msk (3<<(3*2))
#define GPG5_msk (3<<(5*2))
#define GPG6_msk (3<<(6*2))
int main()
{
unsigned long dwDat;
// LED1,LED2,LED3,LED4对应的4根引脚设为输出
GPBCON &= ~(GPB5_msk | GPB6_msk | GPB7_msk | GPB8_msk);
GPBCON |= GPB5_out | GPB6_out | GPB7_out | GPB8_out;
// K1,K2,K3,K4对应的4根引脚设为输入
GPGCON &= ~(GPG0_msk | GPG3_msk | GPG5_msk | GPG6_msk);
GPGCON |= GPG0_in | GPG3_in | GPG5_in | GPG6_in;
while(1){
//若Kn为0(表示按下),则令LEDn为0(表示点亮)
dwDat = GPGDAT; // 读取GPF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)) // K2没有按下
GPBDAT |= (1<<6); // LED2熄灭
else
GPBDAT &= ~(1<<6); // LED2点亮
if (dwDat & (1<<5)) // K3没有按下
GPBDAT |= (1<<7); // LED3熄灭
else
GPBDAT &= ~(1<<7); // LED3点亮
if (dwDat & (1<<6)) // K4没有按下
GPBDAT |= (1<<8); // LED4熄灭
else
GPBDAT &= ~(1<<8); // LED4点亮
}
return 0;
}
makefile
key_led.bin : crt0.S key_led.c
arm-linux-gcc -g -c -o crt0.o crt0.S
arm-linux-gcc -g -c -o key_led.o key_led.c
arm-linux-ld -Ttext 0x0000000 -g crt0.o key_led.o -o key_led_elf
arm-linux-objcopy -O binary -S key_led_elf key_led.bin
arm-linux-objdump -D -m arm key_led_elf > key_led.dis
clean:
rm -f key_led.dis key_led.bin key_led_elf *.o