19

I am using I²C to control a Bright Pi module.

I followed instructions from 'Configuring GPIO - Adafruit' and 'Configuring I²C - Adafruit' to set up the I²C. I have done this a few months ago and everything went fine.

This is how I connected the Bright Pi on my Raspberry Pi (Model B):

Circuit Bright Pi

Since today I noticed the I²C doesn't work anymore as it used to. Using the commands like 'sudo i2cdetect -y 1' and 'sudo i2cset -y 1 0x70 0x00 0xff' will give the error:

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

Using the command 'sudo i2cdetect' will give the error

No i2c-bus specified!

which means the i2c-dev is running.

The file '/etc/modules' looks like this:

#/etc/modules: kernel modules to load at boot time. 
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
# Parameters can be specified after the module name.

snd-bcm2835
i2c-dev
i2c-bcm2708

The file '/etc/modprobe.d/raspi-blacklist.conf' looks like this:

blacklist spi and i2c by default (many users don't need them)

#blacklist spi-bcm2708
#blacklist i2c-bcm2708
blacklist snd-soc-pcm512x
blacklist snd-soc-wm8804

I've tried reinstalling all required modules, but that didn't help either. Also apt-get update and apt-get upgrade didn't help.

The command 'lsmod | grep i2c' shows this:

i2c_bcm2708          6004  0   
i2c_dev              6709  0

It is strange, because it used to work before. I might think it is "broken" since I did a firmware update two days ago, because my Raspberry Pi was showing weird kernel errors.

How can I fix the problem with the I²C?

35

The latest firmware implements device tree support. That will have broken things like I²C, SPI, and 1-wire bus.

For fuller details see I²C, SPI, I2S, LIRC, PPS, stopped working? Read this..

Summary

Add one or more of the following to your /boot/config.txt and reboot.

I2C
No longer add: dtparam=i2c1=on (or dtparam=i2c0=on on old models)
Instead add: dtparam=i2c_arm=on (as this is correctly mapped to 0 or 1 for each model)
A very few users might need: dtparam=i2c_vc=on (for the other i2c interface - see note below)

SPI
Add dtparam=spi=on

I2S
Add dtparam=i2s=on

lirc-rpi
Add dtoverlay=lirc-rpi
Add module parameters to the end of the dtoverlay line,
e.g. dtoverlay=lirc-rpi,gpio_in_pin=16,gpio_in_pull=high

w1-gpio
If you require the external pullup
dtoverlay=w1-gpio-pullup,gpiopin=x,pullup=y
otherwise
dtoverlay=w1-gpio-pullup,gpiopin=x
(where x and y are gpios).

Audio card
Add one of the following
dtoverlay=hifiberry-dac
dtoverlay=hifiberry-dacplus
dtoverlay=hifiberry-digi
dtoverlay=iqaudio-dac
dtoverlay=iqaudio-dacplus

heartbeat LED
dtparam=act_led_trigger=heartbeat

Note: It is recommended that you only use i2c_vc (and i2c_vc_baudrate) if you really need to - for example, if you are programming a HAT EEPROM. Enabling i2c_vc can stop the Pi Camera being detected.

  • You sir, are my hero! This fixed my I2C. – LittleOne Jan 24 '15 at 23:45
7

You can use sudo raspi-config and in Advanced Options disable Device Tree. Might be faster than changing the configuration manually.

1

Or you can just use sudo raspi-config to enable I2C in

Advanced Options > I2C.

for the layout from raspi-config version 20160108, January 2016, or in later versions

Interfacing Options > I2C.

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