Documentation/i2c/summary.rst

2 Introduction to I2C and SMBus
6 a protocol developed by Philips. It is a two-wire protocol with variable
7 speed (typically up to 400 kHz, high speed modes up to 5 MHz). It provides
8 an inexpensive bus for connecting many types of devices with infrequent or
14 The latest official I2C specification is the `"I²C-bus specification and user
15 manual" (UM10204) <https://www.nxp.com/docs/en/user-guide/UM10204.pdf>`_
19 a subset of I2C protocols and signaling. Many I2C devices will work on an
20 SMBus, but some SMBus protocols add semantics beyond what is required to
26 use its protocols on many I2C systems. However, there are systems that don't
34 The I2C bus connects one or more controller chips and one or more target chips.
36 .. kernel-figure::  i2c_bus.svg
37    :alt:    Simple I2C bus with one controller and 3 targets
45 An **algorithm** contains general code that can be used to implement a whole
50 A **target** chip is a node that responds to communications when addressed by a
53 target (needs hardware support) and respond to another controller on the bus.
57 Target drivers are kept in a directory specific to the feature they provide,
59 video-related chips.
61 For the example configuration in the figure above, you will need one driver for
62 the I2C controller, and drivers for your I2C targets. Usually one driver for
66 --------
75 --------------------
80 still find them in references to documentation which has not been updated. The
81 general attitude, however, is to use the inclusive terms: controller and
82 target. Work to replace the old terminology in the Linux Kernel is on-going.