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__TOC__== Overview ==

This How-To is meant to be a starting point for people to learn use GPIOs for IGEP v2 devices as quickly and easily as possible. For this how-to i used [http://releases.linaro.org/platform/linaro-m/headless/final/linaro-m-headless-tar-20101108-2.tar.gz Linaro Headless], Ubuntu 10.04 with Linaro Toolchain, IGEP v2 RC5 and [http://svn.hylands.org/linux/gpio/ GPIO driver] wrote by Dave Hylands. There are more ways to use GPIOs in IGEP v2, but this one is simple and reliable.<br>

= Feedback There are more ways to use GPIOs. This article show two simple ways to use gpios: bash commandline and Contributing =C-code.

At any point, if you see a mistake you can contribute to For this How-ToI used [http://labs.<br> isee.biz/index.php/IGEP_firmware_Yocto IGEP firmware Yocto]

= Compile GPIO driver source code == Feedback and Contributing ===At any point, if you see a mistake you can contribute to this How-To. Edit yourself !

Download source code from author website using the next command== Requirements ==For this How-to, I used:<br> <pre>wget * IGEPv2 Board * Only for C-r -np httpprogram example it also needed:** Add shortcircuit cable between J990:20 and J990://svn22 pins.hylandsBy default, GPIO 156 (J990:20) and GPIO 157 (J990:22) are available on these J990 pins.org/linux/gpio/</pre>

Due the Makefiles are wrote for Gumstix SDK, it is necessary change some constants to our Host. There areAnother boards tested: $/linux/gpio/app/Makefile

Replace by, your cross compiler path, for example:<pre>OVEROTOP ?= /CROSS_COMPILE ?= $(OVEROTOP)/usr/bin/arm-linux-gnueabi-</pre>How to chek an GPIO ==

= Testing driver = Bash commandline ==Basic gpio operations could be done using bash and sysfs :* Export GPIOs <pre>echo "GPIO number NN" > /sys/class/gpio/export</pre>** For example: '''echo "156" > /sys/class/gpio/export'''<br><br>* Unexport GPIOs <pre>echo "GPIO number NN" > /sys/class/gpio/unexport</pre> * Set GPIO direction <pre>echo "out" > /sys/class/gpio/gpioNN/direction</pre>** For example: '''echo "out" > /sys/class/gpio/gpio156/direction'''<br><br>* Set GPIO value =<pre>echo "1" > /sys/class/gpio/gpioNN/value</pre>* Get GPIO value <pre>cat /sys/class/gpio/gpioNN/value</pre>* Configure hardware interrupts <pre>echo "rising" > /sys/class/gpio/gpioNN/edge</pre>

<br> == C-program Example:[[What can I do with IGEP0020#How_to_handle_the_gpio-LED.27s]] ==

C-program Example contains some C-functions to control GPIOs. These also can do:* Export and unexport GPIOs* Set GPIO direction * Set GPIO value * Get GPIO value * Configure hardware interrupts Example program configures a GPIO to wait a hardware interrupt. Once the GPIO value change from 0 value to 1 value (rising), program gives you a message. === Compile example program ===[[Categoryhttp:Work_in_progress]//labs.isee.biz/index.php/How_to_setup_a_cross_compiler#Download.2FInstall_IGEP_SDK Download an Install] IGEP SDK if you don't have it. First of all you need to initialize a suitable environment in the bash shell console inside your machine. <br> You can do this sourcing once the environment-setup script. <pre>jdoe@ubuntu ~ $ source /opt/poky/1.2/environment-setup-armv7a-vfp-neon-poky-linux-gnueabi </pre>  * Download [[Categoryhttp:Communications]//labs.isee.biz/images/6/69/Gpio_examplebeta1.tar.bz2 source code]* Extract source code* Build source code: Cross toolchain tools are available into the built-in virtual machine Poky SDK. You only need open bash terminal prompt and write command: <pre>jdoe@ubuntu ~/Desktop $ arm-poky-linux-gnueabi-gcc -o gpio_example gpio_examplebeta1.c</pre> * Copy binary file to IGEP Board === Execute program ===Open a remote terminal and locate your program binary, execute program and pass like a parameter 157 value (GPIO 157):<pre>root@igep00x0:~# ./gpio_example 157 </pre>Result will be:<pre>root@igep00x0:~# ./gpio_example 157gpio/direction: No such file or directory poll() GPIO 157 interrupt occurred............. </pre> === Generate interrupts ===Open a second remote terminal and type:<pre>cd /sys/class/gpio/echo 156 > export cd gpio156/ echo out > directionecho 0 > valueecho 1 > value</pre> === Result ===At first remote terminal you should read a message similar like this:<pre>poll() GPIO 157 interrupt occurred </pre>