I2C

I²C or I2C (Inter-IC) is a synchronous, multi-controller/multi-target (controller/target), packet switched, single-ended, serial communication bus invented in 1982 by Philips Semiconductors.

Related articles

It is used by many hardware boards to communicate with general purpose I/O (GPIO) devices.

A similar extension of I2C is SMBus which is more specifically used for hardware monitoring purposes.

Installation

I2C kernel modules already exist in most default kernel packages.

Userspace tools can be installed from i2c-tools. Bleeding edge is on i2c-tools-gitAUR.

SMBus-specific tools can be installed from lm_sensors.

Module loading

In some cases it might be required to load the module at boot: 

/etc/modules-load.d/i2c-dev.conf
i2c-dev

Depending on your system and usage, other hardware-specific modules such as i2c_i801 or i2c_smbus might have to be loaded as well.

If the modules are properly loaded, you should see the /dev/i2c-* devices.

Permission for using the /dev/i2c-* devices can be granted by adding the user to the the i2c user group.

Usage

 
can detect all the active I2C devices:

When an I2C device is connected to a known bus, can probe it for active addresses:

See also
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