====== Using GPIO from sysfs ======

=== Where to find GPIO's in sysfs ===

GPIO's are listed under **/sys/class/gpio**


===== Calculate Linux GPIO Number  Freescale i.MX Processor Family =====

Linux GPIO Number = <**GPIO_bank** – 1> × 32 + <**GPIO Port number**>

++++ example | 

<WRAP center round tip 60%>

GPIO2_04 = (2 - 1) * 32 + 4 = GPIO 36 (Linux)
</WRAP>


++++

===== Calculate Linux GPIO Number Texas Instruments Sitara Family =====


Linux GPIO Number = <**GPIO_bank** x 32> + <**GPIO Port number**>

++++ example |
<WRAP center round tip 60%>
GPIO2_04 = 2 x 32 + 4 = GPIO 68 (Linux)
</WRAP>
++++
===== Set GPIO as output =====

<code>
root@MBaXXX:~ echo <gpionr> > /sys/class/gpio/export                 // export GPIO pin
root@MBaXXX:~ echo out > /sys/class/gpio/gpio<gpionr>/direction      // set GPIO direction
root@MBaXXX:~ echo 1 > /sys/class/gpio/gpio<gpionr>/value            // toggle GPIO to high 
root@MBaXXX:~ echo 0 > /sys/class/gpio/gpio<gpionr>/value            // toggle GPIO to low 
</code>
++++ example |
<code>
root@MBaXXX:~ echo 34 > /sys/class/gpio/export
root@MBaXXX:~ echo out > /sys/class/gpio/gpio34/direction
root@MBaXXX:~ echo 1 > /sys/class/gpio/gpio34/value
root@MBaXXX:~ echo 0 > /sys/class/gpio/gpio34/value
</code>
++++
===== Set GPIO as Input =====

<code>
root@MBaXXX:~ echo <gpionr> > /sys/class/gpio/export                 // export GPIO pin 
root@MBaXXX:~ echo in > /sys/class/gpio/gpio<gpionr>/direction       // set GPIO direction
root@MBaXXX:~ cat /sys/class/gpio/gpio<gpionr>/value                 // read GPIO value
</code>

++++ example |
<code>
root@MBaXXX:~ echo 34 > /sys/class/gpio/export
root@MBaXXX:~ echo in > /sys/class/gpio/gpio34/direction
root@MBaXXX:~ cat /sys/class/gpio/gpio34/value
</code>
++++