The C language of GPIO experiment

In the previous chapter, the experiment was programmed using a compilation, and the experiment was written in C language.

(1) Light an LED light

1) Boot file:

Crt. S

. text

. Global _start

_start:

LDR r0,=0x53000000

mov R1, #0x00000000

STR R1,[R0]

LDR Sp,=1024*4

BL Main

Halt_loop:

　　　　　　b halt_loop

2) led.c

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

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

int main ()

{

Gpfcon= 0x00000100; may have an impact on other bits

Gpfdat= 0x00000000;

return 0;

}

3) Makefile

Led.bin:crt. S LED.C

Arm-linux-gcc-g-c-o CRT.O CRT. S

Arm-linux-gcc-g-c-o LED.O LED.C

Arm-linux-ld-ttext 0x00000000-g LED.O Crt.o-o led_elf

Arm-linux-objcopy-o binary-s led_elf Led.bin

arm-linux-objdump-d-M arm led_elf > Led.dis

Clean

Rm-f led_elf Led.dis Led.bin *.o

(2) Running lights experiment

Startup file: Crt. S

Source file: LEDS.C

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

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

#define Gpf4_reset (3<< (4*2))

#define Gpf5_reset (3<< (5*2))

#define Gpf6_reset (3<< (6*2))

#define Gpf4_out (1<< (4*2))

#define Gpf5_out (1<< (5*2))

#define Gpf6_out (1<< (6*2))

void Delay_ms (volatile unsigned long ms)//delay

{

for (; ms>0; ms--);

}

int main ()

{

Gpfcon &=~ (Gpf4_reset | Gpf5_reset | Gpf6_reset);

Gpfcon |= Gpf4_out | Gpf5_out |  Gpf6_out; Output

while (1)

{

Gpfdat &=~ (1<<4);

Delay_ms (30000);

Gpfdat |= (1<<4);

Gpfdat &=~ (1<<5);

Delay_ms (30000);

Gpfdat |= (1<<5);

Gpfdat &=~ (1<<6);

Delay_ms (30000);

Gpfdat |= (1<<6);

}

}

Makefile:

Leds.bin:crt. S LEDS.C

Arm-linux-gcc-g-c-o CRT.O CRT. S

Arm-linux-gcc-g-c-o LEDS.O LEDS.C

Arm-linux-ld-ttext-g CRT.O Leds.o-o leds_elf

Arm-linux-objcopy-o binary-s leds_elf Leds.bin

arm-linux-objdump-d-M arm leds_elf >leds.dis

Clean

Rm-f leds_elf leds.bin Leds.dis *.o

(3) Key control LED

The keys are connected in the form of an external pull-up, where the S2,S3,S4 is connected to the GPF0,GPF2,GPG3 pin of 2440 respectively.

Startup file: Crt. S

Source file: led_key.c

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

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

#define GPGCON (* (volatile unsigned long*) 0x56000060)

#define GPGDAT (* (volatile unsigned long*) 0x56000064)

#define Gpf4_reset (3<< (4*2))

#define Gpf5_reset (3<< (5*2))

#define Gpf6_reset (3<< (6*2))

#define Gpf4_out (1<< (4*2))

#define Gpf5_out (1<< (5*2))

#define Gpf6_out (1<< (6*2))

#define Gpf0_reset (3<< (0*2))

#define Gpf2_reset (3<< (2*2))

#define Gpg3_reset (3<< (3*3))

#define GPF0_IN (0<< (0*2))

#define GPF2_IN (0<< (2*2))

#define GPG3_IN (0<< (3*2))

int main ()

{

Gpfcon &=~ (Gpf4_reset | Gpf5_reset | Gpf6_reset);//Output

Gpfcon |= Gpf_out4 | GPF_OUT5 | GPF_OUT6;

Gpfcon &=~ (Gpf0_rest | Gpf2_reset);

Gpfcon |= gpf0_in | gpf2_in;//the place can not be, because [x:x]=00, through the above statement has been implemented

Gpgcon &=~GPG3_reset;

Gpfcon |= gpg3_in; The service can save

while (1)

{

if (Gpfdat & (1<<0))//Key not pressed

Gpfdat |= (1<<4); Led1 out

Else

gpfdat &=~ (1<<4); Led1 lights up.

if (Gpfdat & (1<<2))

Gpfdat |= (1<<5);

Else

Gpfdat &=~ (1<<5);

if (Gpgdat & (1<<3))

Gpgdat |= (1<<6);

Else

Gpgdat &=~ (1<<6);

}

}

Makefile:

Led_key.bin:crt. S led_key.c

Arm-linux-gcc-g-c-o CRT.O CRT. S

Arm-linux-gcc-g-c-o led_key.o led_key.c

Arm-linux-ld-ttext 0x00000000-g CRT.O led_key.o led_key_elf

Arm-linux-objcopy-o binary-s led_key_elf Led_key.bin

arm-linux-objdump-d-M arm led_key_elf > Led_key.dis

Clean

Rm-f led_key_elf Led_key.dis Led_key.bin *.o

The C language of GPIO experiment