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I am having trouble utilizing the i2c bus on my raspberry pi. I am attempting to use it through Adafruits python module for their Servo driver board. When I run a method using the i2c I get:

IOError: [Errno 2] No such file or directory: '/dev/i2c-1'

When I execute i2cdetect -l I get nothing.

When I execute i2cdetect 1 I get:

Error: Could not open file /dev/i2c-1' or/dev/i2c/1': No such file or directory

(The same happens with 0)

I have tried issuing the command sudo modprobe --first-time i2c-dev

To which I receive:

modprobe: ERROR: could not insert 'i2c_dev': Module already in kernel

The results of journalctl | grep modules are in the following image:

journalctl | grep modules

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1
  • Also when the pi boots I get: " failed to start load kernel modules "
    – Airfield20
    Feb 13, 2017 at 6:34

2 Answers 2

Reset to default
5

Add the following line to /boot/config.txt

dtparam=i2c_arm=on

Add the following line to /etc/modules

i2c-dev

Reboot

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6
  • This did not help. I still have the same exact errors as before.
    – Airfield20
    Feb 13, 2017 at 14:15
  • Is Ubuntu Mate the IoT version? Either way I don't use Mate and if it doesn't properly support device tree you are probably stuffed.
    – joan
    Feb 13, 2017 at 14:26
  • No, it is not the IoT version. Should I be using that? The reason I am using Ubuntu Mate is because I need to install ROS and I had too many issues trying to do that in raspbian jessie.
    – Airfield20
    Feb 13, 2017 at 14:44
  • That is even odder, I could see IoT not being mainstream, but not Ubuntu proper. It should work. Perhaps ask on raspberrypi.org/forums (when it is back up) or a Ubuntu forum. I'm afraid it is a cold hard fact that you will get the best support if you are using Raspbian.
    – joan
    Feb 13, 2017 at 14:50
  • Ubuntu MATE (at least the recent versions) uses Device Tree, and identical kernel and firmware to Raspbian.
    – Milliways
    Feb 13, 2017 at 23:08
2

To enable i2C on the Pi3, do the following:

  1. sudo raspi-config
  2. Choose advanced options
  3. Choose I2C Enable/Disable automatic loading
  4. Follow the prompts to set this to load this automatically
  5. Reboot the Pi

I'd recommend getting the i2C utilities too with:

sudo apt-get install -y i2c-tools

Use:

sudo i2cdetect -y 1

This will display a grid showing what address any devices are using on the i2C bus.

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1
  • 1
    raspi-config is definitely not available for Ubuntu Mate the solution you posted is for raspbian. raspi-config is a front end for the /boot/config.txt file. The solution you posted would add dtparam=i2c_arm=on to /boot/config.txt and also remove i2c from the blacklists file if its listed. The answer posted by joan instructs this but also did not work for my pi.
    – Airfield20
    Feb 14, 2017 at 4:32

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