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authorLuca Ceresoli <luca@lucaceresoli.net>2020-01-29 18:19:27 +0300
committerWolfram Sang <wsa@the-dreams.de>2020-01-30 00:01:13 +0300
commit096c22f88ea09dab449f039863a46cb504b9b3ec (patch)
tree5c772eca0de9f19f7aa8826c614d2867216729ef /Documentation/i2c
parent21593938086fa2886fe07d06aaeb674254a02e3f (diff)
downloadlinux-096c22f88ea09dab449f039863a46cb504b9b3ec.tar.xz
docs: i2c: summary: extend introduction
- state the "official" name (I²C, not I2C, according to the spec) at the beginning but keep using the more practical I2C elsewhere - mention some known different names - add link to the specification document Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net> Reviewed-by: Jean Delvare <jdelvare@suse.de> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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@@ -2,12 +2,18 @@
I2C and SMBus
=============
-I2C (pronounce: I squared C) is a protocol developed by Philips. It is a
-slow two-wire protocol (variable speed, up to 400 kHz), with a high speed
-extension (3.4 MHz). It provides an inexpensive bus for connecting many
-types of devices with infrequent or low bandwidth communications needs.
-I2C is widely used with embedded systems. Some systems use variants that
-don't meet branding requirements, and so are not advertised as being I2C.
+I²C (pronounce: I squared C and written I2C in the kernel documentation) is
+a protocol developed by Philips. It is a slow two-wire protocol (variable
+speed, up to 400 kHz), with a high speed extension (3.4 MHz). It provides
+an inexpensive bus for connecting many types of devices with infrequent or
+low bandwidth communications needs. I2C is widely used with embedded
+systems. Some systems use variants that don't meet branding requirements,
+and so are not advertised as being I2C but come under different names,
+e.g. TWI (Two Wire Interface), IIC.
+
+The official I2C specification is the `"I2C-bus specification and user
+manual" (UM10204) <https://www.nxp.com/docs/en/user-guide/UM10204.pdf>`_
+published by NXP Semiconductors.
SMBus (System Management Bus) is based on the I2C protocol, and is mostly
a subset of I2C protocols and signaling. Many I2C devices will work on an