CubieBoard Docs

1. Make sure that the newest firmware has loaded the module gpio-sunxi.ko by default. (Use the command 'lsmod' to see the module in the list.)
2. Modify script.bin that configure cubieboard file.

• download the sunxi-tools

     $ git clone git://github.com/linux-sunxi/sunxi-tools.git
     $ cd sunxi-tools
     $ make

• modify script.bin

     
     $ mount /dev/nanda /dev/mnt
     $ cp /mnt/script.bin ./
     $ ./bin2fex script.bin >./script.fex
     $ vi script.fex

default GPIO paragraph setup:

[gpio_para]
gpio_used =1
gpio_num = 2
gpio_pin_1 = port: PH20<1><default><default><1>
gpio_pin_2 = port: PH21<1><default><default><1>

modify GPIO port want to use i.e.:

[gpio_para]
gpio_used =1
gpio_num = 3
gpio_pin_1 = port: PD01<1><default><default><1>
gpio_pin_2 = port: PD02<1><default><default><1>
gpio_pin_3 = port: PD03<1><default><default><1>

Save the file, then

$ ./fex2bin script.fex >./script.bin
$ cp  script.bin /mnt 
$ reboot

After rebooted the cubieboard, the new setup will be effective.

3. Operate GPIO port i.e.:

• open the GPIO PD01~03

    $ echo 1 > /sys/class/gpio/export
    $ echo 2 > /sys/class/gpio/export
    $ echo 3 > /sys/class/gpio/export
     </code>
  Below the /sys/class/gpio has appeared directories named gpio1_pd01, gpio1_pd02, gpio1_pd03.
    *set the PD01 por as output <code>
    $ cd /sys/class/gpio/gpio1_pd01
    $ echo out > direction
   </code>
    *set the PD01 port as high<code>
    $ echo 1 > value </code>
    *set the PD01 port as low<code>
    $ echo 0 > value </code>
  
  ====Using raw C program====
  The demo control the PD01 port blink led  :<code>
  #include <stdlib.h>
  #include <stdio.h>
  
  #include "gpio_lib.h"
  #define PD0    SUNXI_GPD(0)
  #define PD1    SUNXI_GPD(1)
  #define PD2    SUNXI_GPD(2)
  #define PD3    SUNXI_GPD(3)
  #define PD4    SUNXI_GPD(4)
  #define MISO    SUNXI_GPE(3)
  #define MOSI    SUNXI_GPE(2)
  #define SCK     SUNXI_GPE(1)
  #define CS      SUNXI_GPE(0)
  
  int main()
  {
      if(SETUP_OK!=sunxi_gpio_init()){
          printf("Failed to initialize GPIO\n");
          return -1;
      }
  
      if(SETUP_OK!=sunxi_gpio_set_cfgpin(PD01,OUTPUT)){
          printf("Failed to config GPIO pin\n");
          return -1;
      }
  
      int i;
      for(i=0;i<5;i++){
          if(sunxi_gpio_output(PD01,HIGH)){
              printf("Failed to set GPIO pin value\n");
              return -1;
          }
  
          usleep(500000);
          if(sunxi_gpio_output(PD01,LOW)){
              printf("Failed to set GPIO pin value\n");
              return -1;
          }
          usleep(500000);
      }
  
      sunxi_gpio_cleanup();
  
      return 0;
  
  }

Save as gpio.c,download gpio_lib,then

gcc gpio_lib.c -c
gcc gpio.c -c
gcc gpio.o gpio_lib.o -o gpio
./gpio

If you have used a led connect GND and PD01 port,the led is going to blink in cycle time.
Of course you can define and use other port .
Use above the method like high-delay-low-delay to simulate PWM output .