I have a CAT6 cable that was used for old temperature sensors that works with 5V I2C at 25/30 meters from the main MCU with cable pairs that brings VCC-GND-SCL-SDA.
Here is the schematic:
I've tried using an ESP32 with I2C bus speed of 100kHz with another PCA9306 at the Gateway end of the cable but it works for maximum 5 meters (and with many errors...)
The speed isn't a problem, i can slow down the speed without any problem.
The cable has a capacitance of 56pf/m, so 30 meters are 1680pf in total, higher than the maximum I2C limit of 400pf.
I know that i2c should not be used outside pcb, etc, etc..i can't change/add nothing more than the main gateway that collects those sensors data.
Now i'm looking for a solution for that: maybe i can use a repeater and level translator like the TCA9517DR and lower the pullup resistor on A-Side in order to fight the cable capacitance?
In any case, i wish have some useful advices about which parts i can use and how i can solve this issue.