Hi can somebody please confirm what the max distance i2c

Hi can somebody please confirm what the max distance between arduino can be using i2c i've trawled the net and there 100s of different answers some say 1 meter and some say 20 and 6 meters

My project will be 5 meters max and 8 ARD Megas some paired and the rest grouped the biggest gap will be 4 meters between groups

Thanks in advance

I2C bus was designed to allow for communications among IC chips on the same PCB or at most within a single chassis at best. However with proper I2C driver/repeaters components added along a bus, I guess it would be possible to extend it to any practical distance required. One could using a O-scope probably optimize a given length/run by adjusting the I2C pull-up resistor values for best observable waveform shape, but there are other interface buses designed for long runs.

I would suggest some extensive real world testing before committing to use I2C.


OK thanks for the rapid reply I guess when my Ard's arrives in post I should just physically test them out then maybe try a BUS EXTENDER P82B715PN

though there is very limited info on setting up and using one

backgrounder about I2C - http://www.gammon.com.au/forum/?id=10896 -