Lines Matching +full:i2c +full:- +full:controller

2 Introduction to I2C and SMBus
5 I²C (pronounce: I squared C and written I2C in the kernel documentation) is
6 a protocol developed by Philips. It is a two-wire protocol with variable
9 low bandwidth communications needs. I2C is widely used with embedded
11 and so are not advertised as being I2C but come under different names,
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>`_
18 SMBus (System Management Bus) is based on the I2C protocol, and is mostly
19 a subset of I2C protocols and signaling. Many I2C devices will work on an
21 achieve I2C branding. Modern PC mainboards rely on SMBus. The most common
22 devices connected through SMBus are RAM modules configured using I2C EEPROMs,
25 Because the SMBus is mostly a subset of the generalized I2C bus, we can
26 use its protocols on many I2C systems. However, there are systems that don't
27 meet both SMBus and I2C electrical constraints; and others which can'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
39    Simple I2C bus
41 A **controller** chip is a node that starts communications with targets. In the
42 Linux kernel implementation it is also called an "adapter" or "bus". Controller
43 drivers are usually in the ``drivers/i2c/busses/`` subdirectory.
46 class of I2C controllers. Each specific controller driver either depends on an
47 algorithm driver in the ``drivers/i2c/algos/`` subdirectory, or includes its
51 controller. In the Linux kernel implementation it is also called a "client".
53 target (needs hardware support) and respond to another controller on the bus.
58 for example ``drivers/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for
59 video-related chips.
62 the I2C controller, and drivers for your I2C targets. Usually one driver for
66 --------
68 As mentioned above, the Linux I2C implementation historically uses the terms
69 "adapter" for controller and "client" for target. A number of data structures
75 --------------------
77 In earlier I2C specifications, controller was named "master" and target was
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.