did you go raspi-config and enable i2c interface
you may install gpio binding on opehab2
with pi4j you must follow pi4j tutorial http://pi4j.com/install.html
and http://pi4j.com/example/control.html
and you must add openhab on gpio and i2c group
sudo adduser openhab gpio
sudo adduser openhab i2c
Hi,
still not works 
The I2C bus works
with the command can set Relais ON/OFF / result I2C is enabled and write works
[19:55:56] pi@myrpi2:~$ i2cset -y 1 0x20 0x14 0x01
[19:56:02] pi@myrpi2:~$ i2cset -y 1 0x20 0x14 0x00
have install PI4J 
curl -s get.pi4j.com | sudo bash
Haven’t install Wiring Pi: No installation is required for Wiring Pi. Wiring Pi is embedded in the Pi4J native library.
Haven’t Test : Simple GPIO Control using Pi4J. do this tomorrow
[20:04:31] pi@myrpi2:~$ java -version
openjdk version “1.8.0_121”
…
[20:05:02] pi@myrpi2:~$ javac -version
javac 1.8.0_121
Use OpenHab : openHAB 2.1.0~20170612235727-1 (Build #947)
have first remove this addon, an replay the flies on add-on :
- org.openhab.binding.gpio-1.9.0.jar
- org.openhab.io.gpio-1.9.0.jar
- org.openhab.binding.mcp23017-1.9.0.jar
on “karaf console” - All module are "Active"
187 | Active | 80 | 1.9.0 | openHAB GPIO IO Module
188 | Active | 80 | 1.9.0 | openHAB GPIO Binding
189 | Active | 80 | 1.9.0 | openHAB mcp23017 Binding
but on the “tail -F /var/log/openhab2/openhab.log /var/log/openhab2/events.log”
Same ERROR
2017-06-15 19:44:21.539 [ERROR] [org.openhab.binding.mcp23017 ] - [org.openhab.binding.mcp23017.binding(177)] Error during instantiation of the implementation object
java.lang.RuntimeException: ERROR; Access to GPIO pins on this system requires priviliged access.
with i2c you can follow : http://www.raspberrypi-spy.co.uk/2013/07/how-to-use-a-mcp23017-i2c-port-expander-with-the-raspberry-pi-part-1/
with pi4j you with see my exameple 
with error you can read my error Above on
Hi,
Is a bit more difficult
pi@myrpi2:/opt/pi4j/examples$ sudo java -classpath .:classes:/opt/pi4j/lib/’*’ MCP23017GpioExample
<–Pi4J–> MCP23017 GPIO Example … started.
Unable to determine hardware version. I see: Hardware : BCM2835, - expecting BCM2708 or BCM2709.
If this is a genuine Raspberry Pi then please report this
to projects@drogon.net. If this is not a Raspberry Pi then you
are on your own as wiringPi is designed to support the
Raspberry Pi ONLY.
this error is Non-root GPIO access broken with 4.9 kernel, for this reason must downgrade to kernel
from 4.9.24+ to 4.4.50+
the command is
sudo rpi-update 52241088c1da59a359110d39c1875cda56496764
after downgrade all feature on PI4J examples works
Now I only have to understand where the error lies in items 
sorry you, i so busy
when i run pi4j on openhab I did not have that problem
but you can Review my guide step by step
you may be reinstall openhab
good luck
Hello,
have reploy new OH2.1.0
- Install I2C work perfect - the relais works
- Install PI4J wok perfect - the relais works
have set Compatible Mode to 1.x
- Paper UI > Configuration > System > Include Legacy 1.x Bindings
have put on OH2 Add-On folder:
- org.openhab.io.gpio-1.10.0.jar
- org.openhab.binding.gpio-1.10.0.jar
- org.openhab.binding.mcp23017-1.10.0.jar
the connect to “karaf console” list all Bundles.
if put mcp23017 in Add-on folder OH2 crash, you see in the picture all bundle “resolved” and will reject from “karaf”
If remove add-on mcp23017 all is perfect, but mcp function not works 
on “tail -F /var/log/openhab2/openhab.log /var/log/openhab2/events.log” don’t see the error.
Do you have an idea
Hi @bodyfix,
try to use 1.9.0 or 1.11.0 version, since 1.10.0 is broken for some reason. I got some days ago follow PM
Kind regards,
Alexander
EDIT: If you use openhabian, may be you run into: GPIO Binding not working · Issue #39 · openhab/openhabian · GitHub
EDIT2: Take a look here: Org.openhab.binding.i2c or org.openhab.binding.mcp23017
Be carefull when you think about migration to 2.1, there is serious bug at least it appears on Rpi environment.
Hi everybody,
i integrated and rebuild MCP* bindings against current Pi4J snapshot. This should solve openHAB start issues (https://www.raspberrypi.org/forums/viewtopic.php?t=182191#p1156722). Jar’s can be found here: https://github.com/falkena/binaries
Can somebody else test, please? If it works, i’ll open PR with fix.
Thanks and kind regards,
Alexander
Hello falkena,
sudo update 52241088c1da59a359110d39c1875cda56496764 isn’t possible in a openHABian-installation.
If I copy the org.openhab.binding.mcp3424-1.11.0-SNAPSHOT.jar and …mcp23017.jar with 839KB (there are also files with 629KB) in the addons library I get
2017-09-11 17:28:17.081 [INFO ] [b.core.service.AbstractActiveService] - mcp3424 Refresh Service has been started
2017-09-11 17:28:17.196 [INFO ] [b.core.service.AbstractActiveService] - mcp23017 Refresh Service has been started
but the bindings aren’t displayed.
SnapShot#1036
Kernel = Linux 4.9.35-v7+
Platform = Raspberry Pi 3 Model B Rev 1.2