When building embedded devices, one of the fundamental activities we do is coupling [suitable CPU A] with [selection of special-purpose peripherals B]. This gets you from having a feature-rich (but boring) SOM to a specialised device offered a wide range of sensory inputs and options. Being an embedded platform however, complexity, pin counts and space is at a premium - so instead of the more powerful IDE, PCI, PCIe or similar interfaces, words like I2C, SPI and RS232 tend to crop up a lot. In this note, I'd like to focus on I2C. I2C (Inter-Integraced Circuit,(http://en.wikipedia.org/wiki/I%C2%B2C), a.k.a. TWSI (Two-Wire Serial Interface), is a mostly-standardised interface using two control lines -- SDA (Serial Data) and SCL (Serial Clock) -- and in-band clocking. In practice, different I2C devices use very similar protocols -- with subtle differences: clocking behavior, addressing, transaction format, etc. Basically, they're all compatible, except when they're not of course. Under Linux, a wide variety of I2C  devices are supported; in addition, Bluewater regularly writes drivers as we use new I2C devices in our designs. At the time of writing, custom-supported I2C devices include:

In addition to Linux, we also use I2C devices in lightweight embedded solutions: Of course, this list will keep expanding as additional devices are used in products.