Looking to build a ribbon cable bus.

I want to build an I2C bus using idc cable and in line connectors. I have dug around in mouser and digikey and come up blank. I can find the cable but not the connectors. I have devices with standard proto pins .1 inch (2.54mm) spacing on my devices. How do you guys build a reliable quick and easy bus?

So, far, I've only been connecting single devices. I use these, and keep the connections short. I made my pinout "standard" the 5-pin connector on the web4robot.com LCD, because it was the first I2C device with a header connection I bought.

If I were going to make a bus, I'd use a 10-pin cable, and ground all the even (or all the odd) pins. That would give me the same pinout as I'm using now, allowing me to connect it to what I already have, and add grounds for better reliability on longer cable runs.

The 10-pin connectors and cable are pretty cheap, and often available surplus to make them even cheaper.


If I were going to make a bus, I'd use a 10-pin cable,

That is not so much of a bus than a star connected fan out topology. This is not good for an I2C bus which works best as a bus, that is a connection to one device going to the next and the next in a chain.

Anyway the I2C bus in not intended to be used as a bus connecting devices that need cable and connectors it is actually meant for connecting ICs on the same board or chips that are quite close to each other.

I recommend cat 5 cable. Actually I think someone else recommended that to me a few months ago, but the post seems to have disappeared now. :frowning: Which is a shame because it had some great links.

My own experiments with two Arduino’s hooked up with telephone wire via I2C showed that communication became unreliable after about 6 feet, failing altogether after about 8 feet (I started at about 12’ and chopped till it worked without errors). Twisting SDA and SCL with ground and Vcc (as in Cat5 cable) provides the high frequency/EMI protection needed for the I2C bus to work properly over lengths greater than a few feet. I doubt that a ribbon would work very well unless it’s more a matter of inches rather than feet.