I2C-Bus: What’s that?
The I2C bus was designed by Philips in the early ’80s to allow easy communication between components which reside on the same circuit board. Philips Semiconductors migrated to NXP in 2006.
The name I2C translates into “Inter IC”. Sometimes the bus is called IIC or I²C bus.
The original communication speed was defined with a maximum of 100 kbit/s, and many applications don’t require faster transmissions. For those that do, there is a 400 kbit/s fast mode and – since 1998 – a 3.4 Mbit/s high-speed mode. More recently, Fast-mode Plus (FM+) has been specified as a transfer rate between the two. Beyond this, there is Ultra Fast-Mode (UFM), which is not a genuine I2C bus in the strict sense.
I2C is not only used on single boards but also to connect components which are linked via cable. Simplicity and flexibility are key characteristics that make this bus attractive to many applications.
Most significant features include:
- Only two bus lines are required
- No strict baud rate requirements like for instance with RS232, the master generates a bus clock
- Simple master/slave relationships exist between all components
Each device connected to the bus is software-addressable by a unique address - I2C is a true multi-master bus providing arbitration and collision detection
Want to learn more?
- Check our I2C Primer.
- The current I2C specification has the revision 7.0 and is dated October 2021, you can find it right here https://www.nxp.com/docs/en/user-guide/UM10204.pdf.
- Have a look at NXP’s overview of I2C devices
- There are a number of I2C-like buses, see Definitions and Differences Between I2C, ACCESS.bus and SMBus.
Looking for I2C tools and software?
Whether you need a high speed I2C solution or a USB I2C interface, whether you want to monitor the bus or need a software platform for your own application, we can help you!