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<<IncludeCSTemplate(TutorialCSHeaderTemplate)>>

<<TableOfContents(4)>>

== Intro ==
This should work with either the Yocto or Debian setup.

== Set up ==
First we have to make sure the permissions are set up to allow users to manipulate GPIO.  
Edit '''{{{/etc/udev/rules.d/99-gpio.rules}}}''' (as root) and make it look like this:
{{{
SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/bin/sh -c 'chown -R root:gpio /sys%p; chown -R root:gpio /sys/class/gpio; chmod -R 775 /sys%p; chmod -R 775 /sys/class/gpio'"
}}}

{{{
sudo groupadd -f --system gpio
sudo udevadm control --reload-rules
}}}

== Command line test ==

{{{
echo -n "3" > /sys/class/gpio/export 
echo "out" > /sys/class/gpio/gpio3/direction 
echo "1" > /sys/class/gpio/gpio3/value
}}}

The LED on the board should turn on

{{{
echo "0" > /sys/class/gpio/gpio3/value
}}}

The LED should turn off

== Control pins with Python ==
Here's a simple Python program to blink the LED:
{{{#!python
#!/usr/bin/python
import sys
import time

def pins_export():
    try:
        pin1export = open("/sys/class/gpio/export","w")
        pin1export.write("3")
        pin1export.close()
    except IOError:
        print "INFO: GPIO 3 already exists, skipping export"

    fp1 = open( "/sys/class/gpio/gpio3/direction", "w" )
    fp1.write( "out" )
    fp1.close()

def write_led( value ):
    fp2 = open( "/sys/class/gpio/gpio3/value", "w" )
    fp2.write( str( value ) )
    fp2.close()


pins_export()
while True:
    print "on"
    write_led( 1 )
    time.sleep( 1 )
    print "off"
    write_led( 0 )
    time.sleep( 1 )   
}}}

See [[http://www.malinov.com/Home/sergey-s-blog|Sergey's Blog]] for pin mapping.

== I2C and PWM ==

It looks like the kernel needs to be compiled with i2c_std_mode = 1 in order to use I2C, PWM and some of the GPIO pins.   If you've followed [[IntelGalileo/HydroGalileoInitialInstall|The Yocto install]] path, you should already be good.

If you've followed the Debian install method, go back to [IntelGalileo/HydroGalileoInitialInstall|the Yocto install]] tutorial.  Once you've got the image bitbaked, do this:

{{{
$ cd ~/gaileo-debian
$ sudo mount -o loop loopback.img mnt-loop
$ sudo mount -o loop ~/devel_gal/meta-clanton_v0.7.5/yocto_build/tmp/deploy/images/image-full-clanton.ext3 image
$ sudo cp -r image/lib/modules mnt-loop/lib
$ sudo sh -c " cat image/etc/modules-load.d/auto.conf >> mnt-loop/etc/modules "
$ sudo umount image
$ sudo umount mnt-loop
$ sudo mount /dev/mmcblk0p1 sdcard
$ sudo rm sdcard/image-full-clanton.ext3
$ sudo cp loopback.img sdcard/image-full-clanton.ext3
$ sudo umount sdcard
}}}




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