ARM bare metal - FS2410 button control LED light (query method)

1. Development Environment

1. Hardware platform: FS2410 (s3c2410)

2. Host: Ubuntu 10.10

2. Hardware schematics (LEDs and buttons)

1. Schematic diagram of LED lamp:

2. Schematic diagram of the buttons:

Wiring resources for buttons:

KSCAN0 -> GPE11    KSCAN1 -> GPG6     KSCAN2 -> GPE13      KSCAN3 -> GPG2

EINT0  -> GPF0     EINT2  -> GPF2    EINT11 -> GPG3     EINT19 -> GPG11

3. Main principles of the procedure:

It mainly involves the four keys K1, K2, K3, and K4. It is necessary to use the query method to determine which key is pressed. Therefore, EINT11 and EINT19 are set as input for reading, and KSCAN0, KSCAN1, and KSACAN2 are set as output, and are set to 0, 1, 1 or 1, 0, 1 or 1, 1, 0 respectively. This can be used to distinguish which key among K1, K2, and K3 is pressed. For example, let KSCAN0~2 = 011 first, then when K1 is pressed, EINT19 will become a low level. At this time, when K2 is pressed, EINT19 will not become low, so that keys K1 and K2 are distinguished. The principle of distinguishing other keys is the same.

4. Register Configuration

1. Configuration of LED registers: (set GPF4-GPF7 as output)

2. The key aspects involve register configuration (setting related register input and output):

5. Detailed code of the program:

led_key.c: (s3c2410.h header file can be found in the keil directory, renamed from s3c2440.h)

#include "s3c2410.h"

void delay(long long max) //delay function

{

for(; max > 0; max--);

}

int main(void)

{

int read_value;

GPFCON = GPFCON & (~(0xff) << 8) | (0x55 << 8); //Set 4 LEDs as output (GPF4-GPF7 output)

GPFDAT |= (0xf << 4); //Turn off all 4 lights first

GPGCON = (0 << 7) | (1 << 12) | (0 << 23); //GPG3, GPG11 input, GPG6, GPE11, GPE13 output

GPECON =  (1 << 22) | (1 << 26);

while(1)

{

GPEDAT &= (0 << 11); //Set GPE11 to 0 and GPE13 and GPG6 to 1

GPEDAT |= (1 << 13);

GPGDAT |= (1 << 6);

read_value = GPGDAT & 0x808; //Read the input values ​​of GPG11 and GPG3

if((read_value & 0x800) == 0) //Judge whether the GPG11 input is 0, and thus whether the K1 key is pressed

{

read_value = 0x800;

delay(200000); //key debounce

if((read_value &= GPGDAT) == 0)

{

if((GPFDAT & (1 << 4)) == 0) //Judge whether D12 is on, if it is on, turn it off, otherwise

GPFDAT |= (0x1 << 4);

else

GPFDAT &= (0xe << 4);

}

}

else

{

if((read_value & 0x8) == 0) //Judge whether the value of GPG3 input is 0, and whether the K4 key is pressed

{

read_value = 0x8;

delay(200000); //key debounce

if((read_value &= GPGDAT) == 0)

{

if((GPFDAT & (0x8 << 4)) == 0) //Judge whether D9 is on, if so, turn it off, otherwise

GPFDAT |= (0x8 << 4);

else

GPFDAT &= (0x7 << 4);

}

}

}

GPEDAT |= (1 << 11); //Set GPE11 and GPE13 to 1 and GPG6 to 0

  GPEDAT |= (1 << 13);

GPGDAT &= (0 << 6);

read_value = GPGDAT & (0x8 << 8); //Read the value of GPG11

if(read_value == 0) //Judge whether GPG11 input is 0, and thus judge whether K2 is pressed

{   

read_value = 0x800;  

delay(200000); //key debounce

if((read_value &= GPGDAT) == 0)

{  

if((GPFDAT & (0x2 << 4)) == 0) //Judge whether D11 is on, if it is on, turn it off, otherwise

GPFDAT |= (0x2 << 4);  

else  

GPFDAT &= (0xd << 4);  

}  

} 

GPEDAT &= (0 << 13); //Set GPE13 to 0 and GPE11 and GPG6 to 1

GPEDAT |= (1 << 11);

GPGDAT |= (1 << 6);

read_value = GPGDAT & 0x800; //Read the value of GPG11

if(read_value == 0) //Judge whether GPG11 is 0 to determine whether the K3 key is pressed

{

read_value = 0x800;

delay(200000); //Debounce the button and delay for a while

if((read_value &= GPGDAT) == 0)

{

if((GPFDAT & (0x4 << 4)) == 0) //Judge whether D10 is on, if it is on, turn it off, otherwise

GPFDAT |= (0x4 << 4);

else

GPFDAT &= (0xb << 4);

}

}

}

return 0;

}

Makefile：

led.bin: start.S led_key.c

arm-none-linux-gnueabi-gcc -c start.S -o start.o

arm-none-linux-gnueabi-gcc -c led_key.c -o led_key.o

arm-none-linux-gnueabi-ld -Ttext 0x30008000 start.o led_key.o -o led_key

arm-none-linux-gnueabi-objcopy -O binary -S led_key led_key.bin

clean:

rm -f *.o led_key.bin

Startup file start.S:

.text

.global _start

_start:

#define WATCHDOG 0x53000000

ldr r0, =WATCHDOG

mov r1, #0

str r1, [r0]

ldr sp, =1024*4

bl main

loop:

b loop

Then execute the following command on the uboot of the development board:

tftp 30008000 led_key.bin

go 30008000