使用汇编代码点亮一个LED灯

汇编代码：

.text

.global _start

_start:

LDR R0,=0x56000010

MOV R1,# 0x00001000

STR R1, [R0]

LDR R0,=0x56000014

MOV R1,#0x00000000

STR R1, [R0]

MAIN_LOOP:

B MAIN_LOOP

相应的Makefile如下：

led_on.bin:led_on.S

arm-softfloat-linux-gnu-gcc -g -c -o led_on.o led_on.S
arm-softfloat-linux-gnu-ld -Ttext 0x0000000 -g led_on.o -o led_on_elf
arm-softfloat-linux-gnu-objcopy -O binary -S led_on_elf led_on.bin
clean:
rm -f led_on.bin led_on_elf *.o

用到的是S3C2410开发板，在开发板上用DNW工具下在led_on.bin文件。开发板是从NANDFLASH启动,使用DNW显示过程如下：

Power on reset
Env.Os_Auto_Flag=ff
<*******************************************>
<* *>
<* S3C2410 Board BIOS *>
<* *>
<* http://www.farsight.com.cn *>
<* *>
<* *>
<*******************************************>
NOR Flash Boot, Read ID is : 0x234b00bf
SST39VF1601 found

Please select function :
0 : USB download file
1 : Uart download file
2 : Write Nand flash with download file
3 : Load Pragram from Nand flash and run
4 : Erase Nand flash regions
5 : Write NOR flash with download file
6 : Set boot params
7 : Set AutoBoot parameter,1:linux 2:wince

选7

Please Input Number:9
.

Please select function :
0 : USB download file
1 : Uart download file
2 : Write Nand flash with download file
3 : Load Pragram from Nand flash and run
4 : Erase Nand flash regions
5 : Write NOR flash with download file
6 : Set boot params
7 : Set AutoBoot parameter,1:linux 2:wince

选4擦除NANDFALSH

Please select which region to erase : Esc to abort
0 : offset 0x0 , size 0x40000 [bootloader]
1 : offset 0x40000 , size 0x1c0000 [zImage]
2 : offset 0x200000 , size 0x1e00000 [cramfs]
3 : offset 0x2000000 , size 0x2000000 [WinCE]
Are you sure to erase nand flash from page 0x0, block count 0x10 ? [y/n]
................Erase Nand partition completed success

Please select function :
0 : USB download file
1 : Uart download file
2 : Write Nand flash with download file
3 : Load Pragram from Nand flash and run
4 : Erase Nand flash regions
5 : Write NOR flash with download file
6 : Set boot params
7 : Set AutoBoot parameter,1:linux 2:wince

选择1通过串口下载bin文件。

Now download file from uart0...
Download File Size = 42
Are you sure to run? [y/n]

Please select function :
0 : USB download file
1 : Uart download file
2 : Write Nand flash with download file
3 : Load Pragram from Nand flash and run
4 : Erase Nand flash regions
5 : Write NOR flash with download file
6 : Set boot params
7 : Set AutoBoot parameter,1:linux 2:wince
现在2

将.bin下载到NANDFLASH

Please select which region to write : Esc to abort
0 : offset 0x0 , size 0x40000 [bootloader]
1 : offset 0x40000 , size 0x1c0000 [zImage]
2 : offset 0x200000 , size 0x1e00000 [cramfs]
3 : offset 0x2000000 , size 0x2000000 [WinCE]
Now write nand flash page 0x0 from ram address 0x30400000, filesize = 36
Are you sure? [y/n]
.Program nand flash partition success

下载成功

Please select function :
0 : USB download file
1 : Uart download file
2 : Write Nand flash with download file
3 : Load Pragram from Nand flash and run
4 : Erase Nand flash regions
5 : Write NOR flash with download file
6 : Set boot params
7 : Set AutoBoot parameter,1:linux 2:wince