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cd /sys/class/gpio

[root@EmbedSky gpio]# cd ./gpiochip0
[root@EmbedSky gpiochip0]# cat label
GPIOA
[root@EmbedSky gpio]# cd ./gpiochip32
[root@EmbedSky gpiochip32]# cat ./label
GPIOB
[root@EmbedSky gpio]# cd ./gpiochip64
[root@EmbedSky gpiochip64]# cat label
GPIOC
[root@EmbedSky gpio]# cd ./gpiochip96
[root@EmbedSky gpiochip96]# cat label
GPIOD
[root@EmbedSky gpio]# cd ./gpiochip128
[root@EmbedSky gpiochip128]# cat label
GPIOE
[root@EmbedSky gpio]# cd ./gpiochip160
[root@EmbedSky gpiochip160]# cat label
GPIOF
[root@EmbedSky gpio]# cd ./gpiochip192
[root@EmbedSky gpiochip192]# cat label
GPIOG
[root@EmbedSky gpio]# cd ./gpiochip224
[root@EmbedSky gpiochip224]# cat label
GPIOH

echo 162 > /sys/class/gpio/export

[root@EmbedSky gpio162]# cat direction
out

[root@EmbedSky gpio162]# cat value
0

[root@EmbedSky gpio162]# echo in > ./direction
[root@EmbedSky gpio162]# cat direction
in

[root@EmbedSky gpio162]# echo out > ./direction
[root@EmbedSky gpio162]# echo 1 > ./value
[root@EmbedSky gpio162]# cat value
1

[root@EmbedSky gpio162]# echo 0 > ./value
[root@EmbedSky gpio162]# cat value
0

[root@EmbedSky gpio162]# echo in > ./direction
[root@EmbedSky gpio162]# cat ./direction
in
[root@EmbedSky gpio162]# cat ./value
1

[root@EmbedSky gpio162]# echo 0 > ./value
[root@EmbedSky gpio162]# cat ./value
1

[root@EmbedSky gpio162]# echo out > ./direction
[root@EmbedSky gpio162]# echo 1 > ./value
[root@EmbedSky gpio162]# cat value
1

echo 162 > /sys/class/gpio/unexport

// Blink pin 3 on port B at 1 Hz
// Just add an LED and see the light! ;)
//
//Created by Dingo_aus, 7 January 2009
//email: dingo_aus [at] internode <dot> on /dot/ net
//
//Created in AVR32 Studio (version 2.0.2) running on Ubuntu 8.04

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

FILE *fp;

int main(int argc, char** argv)
{

   printf("\n**********************************\n"
         "*  Welcome to PIN Blink program  *\n"
         "*  ....blinking pin 3 on port B  *\n"
         "*  ....rate of 1 Hz............  *\n"
         "**********************************\n");
   
   //create a variable to store whether we are sending a '1' or a '0'
   char set_value[4];
   //Integer to keep track of whether we want on or off
   int toggle = 0;
   
   //Using sysfs we need to write "37" to /sys/class/gpio/export
   //This will create the folder /sys/class/gpio/gpio37
   if ((fp = fopen("/sys/class/gpio/export", "ab")) == NULL)
      {
         printf("Cannot open export file.\n");
         exit(1);
      }
   //Set pointer to begining of the file
      rewind(fp);
      //Write our value of "37" to the file
      strcpy(set_value,"37");
      fwrite(&set_value, sizeof(char), 2, fp);
      fclose(fp);
   
   printf("...export file accessed, new pin now accessible\n");
   
   //SET DIRECTION
   //Open the LED's sysfs file in binary for reading and writing, store file pointer in fp
   if ((fp = fopen("/sys/class/gpio/gpio37/direction", "rb+")) == NULL)
   {
      printf("Cannot open direction file.\n");
      exit(1);
   }
   //Set pointer to begining of the file
   rewind(fp);
   //Write our value of "out" to the file
   strcpy(set_value,"out");
   fwrite(&set_value, sizeof(char), 3, fp);
   fclose(fp);
   printf("...direction set to output\n");
   
   //SET VALUE
   //Open the LED's sysfs file in binary for reading and writing, store file pointer in fp
   if ((fp = fopen("/sys/class/gpio/gpio37/value", "rb+")) == NULL)
      {
         printf("Cannot open value file.\n");
         exit(1);
      }
   //Set pointer to begining of the file
   rewind(fp);
   //Write our value of "1" to the file
   strcpy(set_value,"1");
   fwrite(&set_value, sizeof(char), 1, fp);
   fclose(fp);
   printf("...value set to 1...\n");
         
   //Run an infinite loop - will require Ctrl-C to exit this program
   while(1)
   {
      //Set it so we know the starting value in case something above doesn't leave it as 1
      strcpy(set_value,"1");
      
      if ((fp = fopen("/sys/class/gpio/gpio37/value", "rb+")) == NULL)
      {
         printf("Cannot open value file.\n");
         exit(1);
      }   
      toggle = !toggle;
      if(toggle)
      {
         //Set pointer to begining of the file
         rewind(fp);
         //Write our value of "1" to the file
         strcpy(set_value,"1");
         fwrite(&set_value, sizeof(char), 1, fp);
         fclose(fp);
         printf("...value set to 1...\n");
      }
      else
      {
         //Set pointer to begining of the file
         rewind(fp);
         //Write our value of "0" to the file
         strcpy(set_value,"0");
         fwrite(&set_value, sizeof(char), 1, fp);
         fclose(fp);
         printf("...value set to 0...\n");
      }
      //Pause for one second
      sleep(1);
   }
   return 0;
}

main {

...

system("echo 202 > /sys/class/gpio/export");
fd = fopen ("/sys/class/gpio/gpio202","r");
....
поработали с пином
...
fclose(fd);
system("echo 202 > /sys/class/gpio/unexport");

...

}

#define LOOPS 12 // 12 Werte fuer Mittelwert

unsigned int getpoti() {
   int value, i, fd = open("/dev/adc", 0);
   unsigned int add = 0, ret;
   if (fd < 0) { printf("cant open adc device!\n"); return -1; }
   
   for(i = 0; i < LOOPS; i++) {
      char buffer[30];
      int len = read(fd, buffer, sizeof buffer -1);
      if (len > 0) {
         buffer[len] = '\0';
         value = -1;
         sscanf(buffer, "%d", &value);
         add += value;
      } else {
         printf("cant read from adc device!\n");
                        close(fd);
         return -1;
      }
   }
   close(fd);
   ret = add / LOOPS;
   return ret;
}