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I am currently facing the problem that the i2c-dev kernel module is not loaded despite the dtparam=i2c_arm=on being present in /boot/config.txt. Therefore I cannot i2detect fails on me as /dev/i2c-1 is not present. After I execute modprobe i2c-dev it seems to work just fine. Currently, I am running the latest version via raspi-update and have updated all packages via apt-get upgrade. Does anyone know how to fix this issue without doing something like executing modprobe i2c-dev on start up?

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I don't understand device tree well enough to say if this is intended behaviour or a bug.

Device tree loads the driver (i2c_bcm2708) but does not create the devices.

You need to modprobe i2c_dev to create the devices.

Normal procedure is to have the line i2c_dev in /etc/modules so it is modprobed at boot.

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  • Thank you very much, that worked for me. But it still appears as if it really should work without this as it is never mentioned in instructions about the new device tree settings.
    – D0r1an
    Aug 12 '15 at 20:44
  • @D0r1an The chap who seems to maintain the Raspberry Pi device tree should be aware of the issue. I'm fairly sure I've raised it although perhaps only tangentially. See raspberrypi.org/forums/viewtopic.php?p=675658#p675658 for some history.
    – joan
    Aug 12 '15 at 21:07
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    @D0r1an Now asked and answered at raspberrypi.org/forums/viewtopic.php?p=801866#p801866
    – joan
    Aug 13 '15 at 9:20
  • This is great background information. I found it while trying to sort the installation of a ds3231 RTC on my RPi3b. I thought this would be straightforward - in & out in less than 10 minutes. Unfortunately, the issue is that there are many "guides" available, but they all differ. This has the look & feel of a quagmire, I'm still reading & searching, but will likely post a question soon on the correct RTC install procedure. Pls advise if you think that's unnecessary.
    – Seamus
    Apr 4 at 13:25

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