Developing ARM bare metal programs under Ubuntu - S3C6410 - LED

Many people develop ARM bare metal programs in ads, rvds or keil. Although using such development tools is simple, it does not enable developers to master more program principles. If you want to better master more program details, it is better to use arm-linux- for development.

Please indicate the source when reprinting, thank you, Zhang Tonghao: http://blog.csdn.net/muge0913/article/details/15016959

Email: muge0913@sina.com

 

The following is a simple program to light up the LED lamp, running on the tiny6410. The set_peri_port function must be added so that the peripheral space of the s3c6410 can be accessed.

 

@
@ File：led_on.S
@ Function: LED lighting program, light up LED1
@       

.equ		WATCHDOGCON,	0x7e004000
.equ		LEDCON,			0x7f008800
.equ		LEDDAT,			0X7f008808
.text
.global _start
_start:     
			bl		setup_peri_port
			bl		disable_watch_dog
			bl		setup_sp
			bl		display_led
MAIN_LOOP:
            b       MAIN_LOOP



disable_watch_dog:
			@Write 0 to the WATCHDOG register
			ldr r0,=WATCHDOGCON
			mov r1,#0x0
			str r1,[r0]
			mov pc,lr
	
setup_sp:
			@Currently the stack size cannot exceed 8k
			ldr	sp,=1024*8
			mov pc,lr

setup_peri_port:
			ldr r0,=0x70000013		@base addres:0x70000000,size:256MB
			mcr p15,0,r0,c15,c2,4
			mov pc,lr
display_led:
            ldr r0,=LEDCON @ R0 is set to LEDCON, that is, GPKCON0 register. This register
                                    @ Used to select the function of each pin of port K:
                                    @ is output, input, or something else
            mov r1,#0x110000        
            str r1,[r0] @ Set GPK4,5 as output port
            ldr r0,=LEDDAT @ R0 is set to GPKDAT register. This register
                                    @ Used to read/write data of each pin of port B
            mov r1,#0x00000000 @ This value is 0x000000, low level lights up the LED
            str r1,[r0] @ GPK4,5 output 0, LED4,5 lights up
			mov	pc,lr

 

The Makefile is as follows:

 

led_on.bin : led_on.s
	arm-linux-gcc -g -O0 -c -o led_on.o led_on.s
	arm-linux-ld -Ttext 0x0000000 -g led_on.o -o led_on_elf
	arm-linux-objcopy -O binary -S led_on_elf led_on.bin
clean:
	rm -f   led_on.bin led_on_elf *.o