I2C: General


Patented by Philips ages ago.
Patents are supposed to be expired, but nobody knows for sure.
Do not read patent documents. You get infected. And guilty.
TWI, SMBUS and other names are the same thing.
IF you use TWI you can claim it's not I2C.

The name means "Inter Intgrated Circuit" bus: IIC, or I2C.
Originalli 100kb/s, then 400kb/s, now 1MB/s

Two lines, plus power and ground:
SCL: serial clock, open-drain, pulled up by a resistor
SDA: serial data, open-drain, pulled up by a resistor

SDA can only move while SCL is low
There is only one exception: the "start" condition
And there is only one more exception: the "stop" condition