Revision as of 13:43, 9 January 2012

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 Linaro Headless, Ubuntu 10.04 with Linaro Toolchain, IGEP v2 RC5 and GPIO driver wrote by Dave Hylands. There are more ways to use GPIOs in IGEP v2, but this one is simple and reliable.

Feedback and Contributing

At any point, if you see a mistake you can contribute to this How-To.

Compile GPIO driver source code

Download source code from author website using the next command:

wget -r -np  http://svn.hylands.org/linux/gpio/

Due the Makefiles are wrote for Gumstix SDK, it is necessary change some constants to our Host. There are:

$/svn.hylands.org/linux/gpio/app/Makefile

$/svn.hylands.org/linux/gpio/lib/Makefile

Search lines:

OVEROTOP	?= /home/gumstix/overo-oe
CROSS_COMPILE	?= $(OVEROTOP)/tmp/sysroots/x86_64-linux/usr/armv7a/bin/arm-angstrom-linux-gnueabi-

Replace by, your cross compiler path, for example:

OVEROTOP	?= /
CROSS_COMPILE	?= $(OVEROTOP)/usr/bin/arm-linux-gnueabi-

$/svn.hylands.org/linux/gpio/modules/Makefile

Search lines:

OVEROTOP	?= /home/gumstix/overo-oe
#CROSS_COMPILE	?= $(OVEROTOP)/tmp/cross/armv7a/bin/arm-angstrom-linux-gnueabi-
CROSS_COMPILE	?= $(OVEROTOP)/tmp/sysroots/x86_64-linux/usr/armv7a/bin/arm-angstrom-linux-gnueabi-
KERNEL_PATH     ?= ../../../../../gumstix/overo-oe/tmp/sysroots/overo-angstrom-linux-gnueabi/kernel
ARCH		?= arm

Replace by, your cross compiler path and your kernel source path used, for example:

OVEROTOP	?= /
#CROSS_COMPILE	?= $(OVEROTOP)/tmp/cross/armv7a/bin/arm-angstrom-linux-gnueabi-
CROSS_COMPILE	?= $(OVEROTOP)//usr/bin/arm-linux-gnueabi-
KERNEL_PATH     ?= ../../../../../<your kernel source path used>
ARCH		?= arm

Go to: $/svn.hylands.org/linux/gpio/Makefile and compile app, lib and module using make command.

Transfer binaries created to IGEP v2

Install binaries

Install module

Go to:$/svn.hylands.org/linux/gpio/modules/ and insert user-gpio-drv.ko into linux kernel with the following command:

insmod user-gpio-drv.ko

Check that user-gpio-drv.ko is currently loaded with the following command:

lsmod

The module is loaded until system halt.

Install dynamic library

Go to:$/svn.hylands.org/linux/gpio/lib/. libgpio.so will be found here.

You must tell to SO where the dynamic libraries are. Now we define the environment variable LD_LIBRARY_PATH for SO can link a library with a program when a program make a call. Type the follow commnad:

export LD_LIBRARY_PATH=/root/svn.hylands.org/linux/gpio/lib/

Execute app

Go to:$/svn.hylands.org/linux/gpio/app, gpio will be found here.

To make sure that libgpio.so can be founded as a dependency of gpio program use the following command:

<pre>

ldd gpio

</pre>

See if libgpio.so is found it. If you execute program in bash without linking library dependencies, bash give you a error message.

Testing driver

Under construction

Example:What can I do with IGEP0020#How_to_handle_the_gpio-LED.27s