====== 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 64 (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>
++++


====== Using GPIO in U-Boot ======

<WRAP round important> Tested with TQMa28</WRAP>

It is possible to toggle the GPIO's in U-Boot with the gpio command. To use gpio command the desired gpio pin number has to be given as parameter to the command. The following bitmask applies to GPIO pin number in U-Boot:\\  
[PPPP P_BBB] P = pin, B = bank 

For example we toggle GPIO0_24 on MBa28

GPIO0_24 = GPIO Bank 0, Pin 24, 
GPIO0_24 = 11000