I have recently purchased a reel of this specification screened wire from RS Components to use in I2C communications, expecting it to be very well suited to purpose. I am running at approximately 400 kHz clock on the wire and did not think for a second that the choice of cable might limit the speed I could run at. However on oscilloscope inspection, the bus signals are extremely dulled by the connection of a 3m length of this wire.
Is the problem with the I2C master not having a sufficient pullup resistor say, or is the wire genuinely at fault? Is there a significantly better wire specification I could use for this application?
It is true this wire is listed as 95pF/m. I have found a different spec of wire (for microphone use) that seems potentially impossible based on the physics discussed, but here it is, 55-105pF/km.