Arm开发板实验（1）---- 基本功能练习

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Chapter 1: material collection

1.   S3C2440 data sheet;

2.   Arm Assemble instruction;

3.   Develop Board Data Sheet;

4.   Develop environment: arm-linux-gcc3.4.1 u-boot1.1.6

Chapter 2: Led control

1.   Browse the data sheet, utu2440-f-main-v45 sch.pdf, the LED are controlled by EINT4~EINT7.

2.   Browse the data sheet, S3C2440.pdf, to search for the EINT control register. EINT is equal to the GPF, and we can control it via the CPECON Register and the GPFDATA Register.

If we want to turn on the LED1 and LED3 and turn off the LED2 and the LED4, the assemble program is below:

.text                    /.* start of test segment */

.global _start             /.* illustrate the type of the symbol _start */

_start:                   /.* a symbol */

LDR  R1, =0x56000040   /.* move the immediate number to the R1 */

MOV R2, #0x00005500    /.* move the short immediate number to the R2 */

STR  R2, [R1]           /.* store the value pointed by R1 to R2 */

LDR  R1, =0x56000044

MOV R2, #0x000000F0

STR  R2, [R1] 

MAIN_LOOP:

B    MAIN_LOOP       /.* dead loop */

Chapter 3: C Language Init Error

Oh my God, I have finished my first C Language program: Led On.

At first, the CPU can not run the C Language functions. The User must initialize the environment that the C Languae need. It contains the stack and lr registers. The first funtions (entry point) should be a Assemble function. its contents is below:

/* ctr0.s: used to set the environment of C Language */

.text

.global _start

_start:

ldr sp,=0x1000   /* set stack */

bl main

halt_loop:

b halt_loop

Note: the stack’s start address is 0x1000. Why? Why not at the SDRAM (0x30000000)?  That’s because the special of s3c2440. It has a 4K ram in the chip .  Usually, it is used to store the boot code. After the booting, we can erase it and use it as the stack at Init period.

the makefile is below:

SRC_PATH = .

TOOL_PATH = tools

OBJ_PATH = tmp

TEST_SRC = $(wildcard *.c)

TEST_ASM = $(wildcard *.s)

TEST_OBJ = $(addprefix $(OBJ_PATH)/,$(subst .c,.o,$(TEST_SRC)))

TEST_OBJ += $(filter-out $(OBJ_PATH)/crt0.o,$(addprefix $(OBJ_PATH)/,$(subst .s,.o,$(TEST_ASM))))

.PHONY:default

default:$(OBJ_PATH)/test.bin

       @echo "start compile"

$(OBJ_PATH)/test.bin:$(OBJ_PATH)/crt0.o $(TEST_OBJ)

       arm-linux-ld -Ttext 0x30000000 -e _start -g $^ -o $(subst .bin,.elf,$@)

# convert the kernel into a raw binary image:

       arm-linux-objcopy -O binary -R .note -R .comment -S $(subst .bin,.elf,$@) $@

$(OBJ_PATH)/%.o:%.s

       mkdir -p $(OBJ_PATH)

       arm-linux-gcc -g -c $< -o $@

$(OBJ_PATH)/%.o:%.c

       mkdir -p $(OBJ_PATH)

       arm-linux-gcc -g -c $< -o $@

 

the led_on.c is below:

 

#define GPFCON (*(volatile unsigned long *)0x56000050)

#define GPFDAT (*(volatile unsigned long *)0x56000054)

int main()

{

    GPFCON = 0x00005500;

    GPFDAT = 0x000000a0;

    while(1);

}

 

When I finished the compile, I downloaded the test.elf to the board and run it by below command:

> tftp 0x30000000 test.elf

> go 0x30000000

 

Then an error occurred and the log was below:

 

## Starting application at 0x30000000 ...

undefined instruction

pc : [<30000024>]    lr : [<33f89ad0>]

sp : 33d5fb44  ip : 00000001  fp : 00000000

r10: 33d5fd71  r9 : 00000000  r8 : 33d5ffdc

r7 : 33d5fc71  r6 : 00000002  r5 : 33d5fe68  r4 : 30000000?

 

The reason is that the file I should download is th test.bin, not the test.elf. The elf file is a kind of file format. It cannot run directly in the memory. The bin file is the memory image, so it can run directly in the memory.

 

Chapter 4: compile the linux kernel

The first problem is that there was no the file: curses.h, so that I cannot run the command, make menuconfig, to config the kernel. I searhed on the Baidu and find the problem is the lack of libcurses. Run command as below in the termimal:

apt-get install libcurses*-dev

Then I can run the “make menuconfig”.

The second problem is that the target “prepare3” in the top makefile(896) should not run the command, so I delete the it:

 

Original

prepare3: include/config/kernel.release ifneq ($(KBUILD_SRC),)        @echo '  Using $(srctree) as source for kernel'        $(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \               echo "  $(srctree) is not clean, please run 'make mrproper'";\               echo "  in the '$(srctree)' directory.";\               /bin/false; \        fi;        $(Q)if [ ! -d include2 ]; then mkdir -p include2; fi;        $(Q)ln -fsn $(srctree)/include/asm-$(SRCARCH) include2/asm endif

New

prepare3: include/config/kernel.release

 

The last problem is that the command, “cp ./drivers/video/logo/logo_linux_240320_clut224.ppm ./drivers/video/logo/logo_linux_clut224.ppm”, can not be executed. I should change the first “.” to “..”, as below:

“cp ../drivers/video/logo/logo_linux_240320_clut224.ppm ./drivers/video/logo/logo_linux_clut224.ppm”.

Now, I can finish the compile of the kernel. The next step is to modify the config from the sdk2410 to sdk2440.

Good night.

本文乃fireaxe原创，使用GPL发布，可以自由拷贝，转载。但转载请保持文档的完整性，并注明原作者及原链接，严禁用于任何商业用途。
作者：[e-mail]

博客：fireaxe.blog.chinaunix.net