刚刚接触树莓派，的确很适合用来学习，资料多而且很规范，开发者多，平台统一，很多问题别人都已经解决。
买的是带3.5电阻屏的版本， 使用i2c接传感器，但是总是报错：
1. 执行 sudo raspi-config 开启i2c的时候：
There was an erro running option A6 I2C
2.终端中：
FATAL: Module i2c-dev not found.
3.lsmod命令显示：
只有i2c_bcm2708
没有i2c-dev
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最终的问题是这块带3.5屏的内核中没有将相关i2c模块加进去，通过跟新内核，就可以解决问题，跟新了1个小时。没有尝试直接将相关模块添加进去行不行。不过更新过之后确实i2c可以使用，但3.5寸白屏了。
最终解决问题用到的网页：https://www.raspberrypi.org/forums/viewtopic.php?t=157458&p=1025165
Run sudo rpi-update to get the 4.4.17 kernel and replace your missing modules.
You'll need to reinstall your screen drivers.
http://www.kedei.net/raspberry/raspberry.html
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一些比较好的网站：
http://www.cnblogs.com/hangxin1940/archive/2013/04/03/2997094.html 树莓派搭建python i2c开发环境
http://www.landzo.cn/thread-12826-1-1.html
http://www.cnblogs.com/hangxin1940/archive/2013/04/02/2997077.html 树莓派启用i2c设备
http://www.raspberrypi-spy.co.uk/2014/11/enabling-the-i2c-interface-on-the-raspberry-pi/
http://blog.csdn.net/xukai871105/article/details/18234075
http://blog.csdn.net/ki1381/article/details/52425565
http://blog.csdn.net/xdw1985829/article/details/39580401 树莓派GPIO控制
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网上的一些说法：
1.首先是raspi-config配置
2./boot/config.txt 文件中开启
dtparam=i2c_arm=on
(enable the hardware interface)
3. /etc/modprobe.d/raspi-blacklist.conf配置文件里注释掉：
bladklist i2c-bcm2708
4./etc/modules-load.d/modules.comf
在此配置文件中添加：
i2c-dev
这样在开机的时候，内核引导启动的时候就会加载这个驱动模块：（ kernel modules to load at boot time）
5.或者临时添加：
sudo modprobe i2c-dev
一些相关的网页：
https://www.zhihu.com/question/29328394
http://blog.csdn.net/xukai871105/article/details/15029843
http://blog.csdn.net/fly_qj/article/details/44204661
Hello to all,
I'm new here and I use a RPI for several applications.
Most of them are sensors which are connected to the i2c-port.
Now I have one problem using a LCD-display.
I do not know what drivers I need for this.
The supplier provides a image (=Linux rpizero 4.4.11 #2 Tue May 24 22:50:33 CST 2016 armv6l GNU/Linux) which works very good for the LCD display 
. But...
I can not use the i2c port.
If I run
raspi-config
I get the following message:
There was an error running option A6 I2
and
modprobe: FATAL: Module i2c-dev not found.
I think I need to add the i2c modules to the image.
I have 2 questions:
- what i2c module do I need?
- where can i get this?
- how to add this modules ti the image?
You see I'm not an expert in making kernel.
Please can anybody give me a hint how to solve this problem?
Thanks a lot in advance!
Kurt