s3c2440 ARM9 bare metal driver first article - GPIO driver (assembly)

1. Development environment:

1. Ubuntu

2.JZ2440 development board

Hardware

The four pins GPF4-7 on the JZ2440 development board are connected to external LEDs. From the circuit diagram, we can see that the LED lights up when the IO port is at a low level.

According to the s3c2440 datasheet, the GPF pin register address is as follows:

Three software parts:

led.s

.text

.global _start

_start:

ldr r0 ,= 0x53000000 @WATCHDOG ADD

mov r1 ,#0x0

str r1 ,[r0] @r1 data is written to r0 

ldr r0 ,=0x56000050 @GPFCON

mov r1 ,#0x5500        

str r1 ,[r0] @Set GPF4-7 to output

add r0 ,r0,4 @GPFDAT

mov r1 ,#0x0

str r1 ,[r0]

loop:

      b loop

Makefile

CC=arm-linux-gcc

LD=arm-linux-ld

led.bin:led.o

    $(LD) -Ttext 0x0000000 -g led.o -o led_elf

    arm-linux-objcopy -O binary -S led_elf led.bin    

    arm-linux-objdump -D -m arm led_elf > led.dis

led.o:led.s

    $(CC) -c -g -o led.o led.s

clean:

    rm -f led.bin led_elf led.dis

Enter mak in the virtual machine to get the led.bin file

Four burning:

I use BootLoader to burn nandflash

1. Download led.bin via tftp to 30000000.

       tftp 30000000 led.bin

2. Erase the nandflash bootloader partition (the partition in the BootLoader provided by Teacher Wei is the first 256k memory of nandflash)

      nand erase bootloader

3. Write to nandflash

    nand write 30000000 bootloader

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Original link: https://blog.csdn.net/ggz_qq1300046380/article/details/78439157