what I2C means?

while watching the examples in the frc libarys in LabVIew , i found some examples containing a thing called “I2C”.
Can someone please tell me what that means?

It’s a BUS. Similar to the USB. (Universal Serial Bus)

In theory you can have a bunch of sensors daisy chained to each other on only on two wires, and still be able to receive and transmit data from each individual sensor. Other than that i don’t know much about it. But, you can do some neat things with the I2C bus. For a neat way to use the I2C bus with an array of RGB Leds watch the youtube link.



I2C is a generic and widely used digital communication protocol for “simple electronics” - http://en.wikipedia.org/wiki/I%C2%B2C It is commonly used to allow a microprocessor to talk to a bunch of simple devices such as memory, sensors, ADCs or intelligent batteries. Check out the Wikipedia link for more examples, my list is by no means exhaustive.

NXT uses I2C to talk to some of its sensors. The DSC provides support to talk to those same sensors. Be careful though, not all NXT sensors use I2C. I2C sensors are also available from many other sources.

I2C allows a processor to use 2 pins to talk to many devices. If you are interested in electronics, I’d recommend looking into how it does this - it is a very cheap but decent method.

The new system also supports SPI, which is a digital communication protocol that competes in the same niche of “super simple for simple tasks”. I’m excited to see what teams will end up doing with these two buses.


It is a 4 wire connection from computers to devices, plus the serial protocol for addressing and talking to the devices. The Wii uses IC2 over the cord between the Wii Remote and the Nunchuk.

As was stated before, it only uses two wires, a data line and a clock signal line. Other signals are sometimes passed with it, such as ground and power, but those aren’t officially part of the bus specification. Compare with something like SPI (previously mentioned) that has additional signals for chip select and a second data line so it can run in full duplex (a device can send and receive at the same time)

You are quite right in that I2C only requires 2 pins of the processor for the signaling and it can be made to work only over 2 wires if a bridge has been used and the device doesn’t have the same power source as the processor. However, in practice the devices and the processor share a common Vdd wire for power and a ground wire - total 4 wires. If you cut the cord between the Wii remote and the Nunchuk there are 4 wires - that’s all I was attempting to convey.

The specification from Phillips details all the various electrical requirements for those interested, wikipedia does not.