Hello,
I am trying to use a I2C display with an arduino uno, the arduino and the display are connected with about 1.7m (5.5 feets) of twisted UTP cable. there is connection between the cables. The display remains black, I tried the same display with some small cables and its working, I would like to know if there is a limitation the this and how can I "bypass" it.
Thanks.
I2C was designed and intended for communications between ICs on a single PCB.
It rarely works well, or at all, with wires more than a few cm long. Reducing the value of the pullup resistors can increase the usable connection length a little.
The best solution is to place the Arduino and the display very close together.
How..
SCL/GND on one pair, and SDA/supply on a second pair is ok.
SCL/SDA on the same pair is not.
Which type of I2C.
A FastMode+ slave can tolerate lower pull up resistors than default I2C devices.
Default 100k gets further than fastmode 400kHz.
One FM+ slave with 4k7 pull up at both ends of two twisted pairs should be able to bridge 2m.
But as jremington said "not designed for that", so don't be surprised if it doesn't work.
Leo..
Run a ground with the SCL, another with the SDA and another pair for power. Take your pull up resistors to about 2K for a 5V system. Good luck, this is not recommended but it may work. If this is in an electrical noisy environment expect problems.