I2C is a short name for Inter-Integrated Circuit. I2C is a simple two-wire serial protocol used to communicate between chips in an embedded system. I2C has two lines SCL and SDA, SCL is used for clock and SDA is used for data.
I2C is really not designed as a protocol over the cable. The convenience of I2C allows additional chip or circuit module to be added without affect the overall circuit design. This popularity and convenience of I2C lead to people using it as a protocol to communicate between 2 circuit modules over a cable. This cable is usually 4 wires. Two wires SDA and SCL for the data. Two wires VCC and GND for the power. VCC for I2C cable is usually either 5V or 3.3V.
Over the years, circuit modules producing companies starts to come up with their own name of their I2C ecosystem standard. They are still the same basic I2C 4 wires cable. However the type of connector used and the pin out varies. These leads to some variation of I2C cable system standard.
There is not yet an international standard of a I2C cabling system. The following presents the available I2C cable and pin out of varies brand on the market.
At this moment of writing, there is 5 types of I2C cable system that I have found, out of the seven I2C system brand name. Those with the same background color means that the cabling system is compatible and can be inter-swap with one another.
The recommended standard I2C cabling to implement, I would personally prefer to follow
- Grove (Seeed Studio), STEMMA (Adafruit) for standard I2C cabling system.
- qwIIC (Sparkfun), STEMMA QT (Adafruit) for mini-connector I2C cabling system.
Breakout Garden (PIMORONI)
2.54mm pitch
nodeLynk Interface
2.54mm pitch
