sdram 裸机程序

硬件平台：JZ2440

实现功能：将led闪烁代码从2440的2k sram中拷贝到sdram

start.s --> 上电初始化，拷贝代码

sdram.c --> led代码

start.s 源码：

.equ MENRI_BASE, 0x48000000

.equ SDRAM_BASE, 0x30000000

.text

.global _start

_start:

        bl close_watchdog

        bl sdram_set

        bl copy_sram_to_sdram

        ldr pc,=on_sdram

on_sdram:

        ldr sp,=0x34000000

        bl main

loop1:

       b loop1

close_watchdog:

        ldr r0,=0x53000000

        mov r1,#0x0

        str r1,[r0]

        mov pc,lr

copy_sram_to_sdram:

        ldr r0,=SDRAM_BASE

        mov r1,#0x0

        mov r3,#*

l:

        ldr r4,[r1], #

        str r4,[r0],#

        cmp r1, r3

        bne l

         mov pc,lr 

sdram_set:

        mov r1,#MENRI_BASE

        adrl r2,mem_reg_set

        add r3,r1,#

m:

        ldr r4,[r2],#

        str r4,[r1],#

        cmp r1,r3

        bne m

        mov pc,lr

.align

mem_reg_set:

.long  0x22011110

.long  0x00000700

.long  0x00000700

.long  0x00000700

.long  0x00000700

.long  0x00000700

.long  0x00000700

.long  0x00018005

.long  0x00018005

.long  0x008c07a3

.long  0x000000b1

.long  0x00000030

.long  0x00000030

sdram.c 源码：

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

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

#define LED1_ON   (1<<8)

#define LED2_ON   (1<<10)

#define LED3_ON   (1<<12)

void delay(unsigned long num)

{

    while(--num);

}

int main(void)

{

    GPFCON=LED1_ON|LED2_ON|LED3_ON;

    while()

    {

        GPFDAT=(<<);

        delay();

        GPFDAT=(<<);

        delay();

        GPFDAT=(<<);

        delay();

    }

    return ;

}

编译的Makefile：

sdram.bin:start.s sdram.c

    arm-linux-gcc -o start.o -c start.s

    arm-linux-gcc -o sdram.o -c sdram.c

    arm-linux-ld -Ttext 0x3000000 -o sdram_elf start.o sdram.o

    arm-linux-objcopy  -O binary -S sdram_elf sdram.bin

    arm-linux-objdump -D -m arm sdram_elf > sdram.dis

clean:

    rm *.o *.dis *.bin sdram_elf

巴特西

sdram 裸机程序

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