==== Cubieboard pin ====
Cubietruck         [[http://docs.cubieboard.org/a20-cubietruck_gpio_pin]]

Cubieboard 1 2 [[http://docs.cubieboard.org/cubieboard1_and_cubieboard2_gpio_pin]]

Fex Guide   [[http://linux-sunxi.org/Fex_Guide]]

A10 Datasheet  [[http://dl.linux-sunxi.org/A10/A10%20Datasheet%20-%20v1.21%20(2012-04-06).pdf|A10 Datasheet(For Pin multiplexing reference）]]

A20 Datasheet  [[http://dl.cubieboard.org/software/ubuntuone/public/cubieboard/docs/A20_user manual V1.0 20130322.pdf|A20 user manual V1.0 20130322.pdf(datasheet)]]





====Using sunxi-gpio kernel module====

 1. Make sure that the newest firmware has loaded the module gpio-sunxi.ko by default and it has added the command include fex2bin bin2fex. (Use the command 'lsmod' to see the module in the list.)\\
 2. Modify script.bin that configuration file of cubieboard.
   *modify script.bin
<code>   
   $ mount /dev/nanda /mnt
   $ cd  /mnt
   $ bin2fex script.bin script.fex
   $ vi script.fex
</code>
default GPIO paragraph setup:
<code>
[gpio_para]
gpio_used =1
gpio_num = 2
gpio_pin_1 = port: PH20<1><default><default><1>                //PH20 is connecting  the green LED
gpio_pin_2 = port: PH21<1><default><default><1>                //PH21 is connecting  the blue LED
</code>
modify GPIO port want to use e.g.:
<code>
[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>
</code>
Save the file, then
<code>
  $ fex2bin script.fex script.bin
  $ reboot
</code>
After rebooted the cubieboard, the new setup will be effective.

 3. Operate GPIO port e.g.:

  *open the GPIO PD01~03 
<code>
  $ 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, gpio2_pd02, gpio3_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 C program without driver====

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;
   
}
</code>
Save as gpio.c,download [[http://dl.cubieboard.org/software/libs/gpio.tar|gpio_lib]],then<code>
$sudo apt-get install gcc build-essential
$tar -xf gpio.tar 
$cd gpio/
$gcc gpio_lib.c -c
$gcc gpio.c -c
$gcc gpio.o gpio_lib.o -o gpio
$./gpio
</code>
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 .\\

====Using  mmap mapping IO address====
<code>

	///////////////////////////////////////////////////////////////////////////////
	#include <ctype.h>
	#include <string.h>
	#include <stdlib.h>
	#include <stdio.h>
	#include <math.h>
	#include <time.h>
	#include <signal.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <fcntl.h>
	#include <sys/mman.h>
	#include <sys/select.h>
	#include <pthread.h>
	#include <unistd.h>
	#include <sched.h>
	#include <errno.h>


	#define SW_PORTC_IO_BASE  0x01c20800

	int main() {
	   unsigned int * pc;
	   int fd, i;
	   char * ptr;
	   unsigned int addr_start, addr_offset, PageSize, PageMask, data;

	   PageSize = sysconf(_SC_PAGESIZE);
	   PageMask = (~(PageSize-1));
	   addr_start = SW_PORTC_IO_BASE & PageMask;
	   addr_offset = SW_PORTC_IO_BASE & ~PageMask;

	   fd = open("/dev/mem", O_RDWR);
	   if(fd < 0) {
	      perror("Unable to open /dev/mem");
	      return(-1);
	   }

	   pc = mmap(0, PageSize*2, PROT_READ|PROT_WRITE, MAP_SHARED, fd, addr_start);

	   if(pc == MAP_FAILED) {
	      perror("Unable to mmap file");
	      printf("pc:%lx\n", (unsigned long)pc);
	      return(-1);
	   }
	   printf("PageSize:%8.8x\tPageMask:%8.8x\naddr_start:%8.8x\taddr_offset:%8.8x\n",PageSize,PageMask,addr_start,addr_offset);
	   printf("pc:%8.8x\n", *(unsigned int *)pc);
	   ptr = (char *)pc + addr_offset;
	   data = *(unsigned int *)(ptr+0x10c);
	   for(i=0;i<1000;i++){
	      data |= 1<<20;                              //green led connect PH20
	      *(unsigned int *)(ptr+0x10c) = data;
	      usleep(100000);
	      data &= ~(1<<20);
	      *(unsigned int *)(ptr+0x10c) = data;
	      usleep(500000);
	   }

	   return 0;
	}


</code>

save as test.c,then 
<code>
$sudo apt-get install gcc build-essential
$gcc test.c -o test
$./test &


</code>
The green LED is blinking  in cycle time.You can modify the ''data |= 1<<20;'' and ''data &= ~(1<<20);'' to use PH15 like ''data |= 1<<15;'' and ''data &= ~(1<<15);''.If you have used a led connect VCC and PH15 port,the led is going to blink in cycle time.\\