I2Cのソースを表示

[[Category:ハードウェア]]
[[en:I2C]]
[[pl:I2C]]
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{{Related|Lm_sensors}}
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[[Wikipedia: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.

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

A similar extension of I2C is [http://www.smbus.org/ 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 {{Pkg|i2c-tools}}. Bleeding edge is on {{AUR|i2c-tools-git}}.

SMBus-specific tools can be installed from {{Pkg|lm_sensors}}.

== Module loading ==

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

{{hc|/etc/modules-load.d/i2c-dev.conf|
i2c-dev
}}

This will not be needed after {{Bug|76233}} is fixed.

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

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

Permission for using the {{ic|/dev/i2c-*}} devices can be granted by adding the user to the {{ic|i2c}} [[user group]].

== Usage ==

{{ic|i2cdetect}} can detect all the active I2C devices:

{{hc|$ i2cdetect -l|
i2c-0	i2c       	Synopsys DesignWare I2C adapter 	I2C adapter
i2c-1	i2c       	Synopsys DesignWare I2C adapter 	I2C adapter
i2c-2	i2c       	Synopsys DesignWare I2C adapter 	I2C adapter
i2c-3	i2c       	Synopsys DesignWare I2C adapter 	I2C adapter
i2c-4	smbus     	SMBus I801 adapter at f040      	SMBus adapter
i2c-5	i2c       	i915 gmbus dpb                  	I2C adapter
i2c-6	i2c       	i915 gmbus dpc                  	I2C adapter
i2c-7	i2c       	i915 gmbus misc                 	I2C adapter
i2c-8	i2c       	AUX B/DDI B/PHY B               	I2C adapter
}}

When an I2C device is connected to a known bus, {{ic|i2cdetect}} can probe it for active addresses: 

{{hc|$ i2cdetect 1|
    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- 76 --
}}

Be wary that this program can confuse your I2C bus, cause data loss and worse.

== See also ==

* https://www.i2c-bus.org/
* http://www.smbus.org/