##GPIO Sysfs user interface (deprecated)

GPIO Sysfs is the standard way to manage the GPIO lines under Linux from user space. 
It uses the directory <b>/sys/class/gpio</b> to set or read any GPIO line.

Inside this directory there are two directories called:

* export
* unexport

To manage a GPIO line you have to know its kernel ID. The Kernel 
IDs of any Acme Systems SoM are available on:

* @article='pinout_all'
* @article='pinout_kernelid'

The Atmel chips have the GPIO lines organized by 32 bit port called PA,PB, etc.

Before set or read a port you have to export it. Follow an example on how to set, reset 
and read the port PA1 (Kernel ID 1) from the command line:

Set the line status of GPIO line PA1

	# echo 1 > /sys/class/gpio/export
	# echo out > /sys/class/gpio/pioA1/direction
	# echo 1 > /sys/class/gpio/pioA1/value

Reset the line status of GPIO line PA1

	# echo 0 > /sys/class/gpio/pioA1/value

Read the line status of GPIO line PA1

	# echo in > /sys/class/gpio/pioA1/direction
	# cat /sys/class/gpio/pioA1/value

The official documentation about the GPIO Sysfs interface is available on:

* [GPIO Sysfs Interface for Userspace](https://www.kernel.org/doc/Documentation/gpio/sysfs.txt)