开发环境


1、硬件平台：FS2410（s3c2410）

2、主机：Ubuntu 12.04 LTS


LED原理图

214317385.jpg


LED的GPIO的配置


    • 配置GPFCON寄存器，设置GPF4-7为输出

    • 配置GPFDAT，设置LED灯亮与灭

214510552.jpg



主要步骤


    • 通过设置GPFCON将GPF4-7设置为输出

    • 设置GPFDAT，可以将led灯亮或灭，GPFDAT的相应位置1灯灭，置0灯亮


源代码

   NAND flash启动

    1. 关狗 

    2. 设置栈

//start.S

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.text
.global _start
_start:
#define WATCHDOG 0x53000000
     ldr r0, =WATCHDOG    //关看门狗
     mov r1, #0
     str r1, [r0]
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
     ldr sp, =1024*4    //设置堆栈
     bl main      //跳转进入main函数
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
loop:
     b loop

//led.c (s3c2410.h 网上找，其中包含option.h，我找了一段时间，所以上传附件了)

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#include "s3c2410.h"
void  delay( long  long  max)     //延迟函数
{
     int  i, j;
     for (i = 0; i < max; i++)
         for (j = 0; j < max; j ++);
}
int  main( void )
{
     int  i;
     GPFCON = GPFCON & (~(0xff << 8)) | (0x55 << 8);     //设置GPF4-7为输出
     GPFDAT &= ~(0xf << 4);      //将4个LED灯开启
     while (1)
     {
         for (i = 0; i < 5; i++)
         {
             GPFDAT = GPFDAT | (0xf << i);   //利用循环设置流水灯     
             delay(500);
         }
         GPFDAT &= ~(0xf << 4);    //4个LED灯开启
     }
     return  0;
}

//Makefile

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led.bin: start.S led.c                                               
     arm-linux-gcc -c start.S -o start.o
     arm-linux-gcc -c led.c -o led.o
     arm-linux-ld -Ttext 0x30008000 start.o led.o -o led
     arm-linux-objcopy -O binary -S led led.bin
   6 clean:
     rm  -f *.o led.bin



步骤


   ①首先make

215349887.jpg

   可以看见生成了led.bin文件

   ②下载到开发板215533834.jpg

   由于我用的bootloader是出厂自带的，而这个bootloader里面没有tftp，所以这里用古老的zmodem协议，但是在下载过程中报告失败，囧……

   于是我换到windows下220057719.jpg


   OK，大功告成，流水灯很顺利


小结


   好久没玩arm裸机了，这次只是在linux下测试下环境

   可以看见，linux下的编程并没有比windows下多多少东西，也就一个Makefile而已，但是对于过程而言，就清楚多了