Ethernet cable (a.k.a., CAT-5/CAT-6 cable) is perfect for extending your I2C sensors using the LTC4311. By doubling up the eight conductors we can get a nice, clean signal to run upwards of 100 feet / 30 meters of distance!

Here's a nice way to connect your STEMMA QT devices to the Ethernet cable, using some hookup wire, heat shrink tubing, and a pair of RJ-45 adapters.

Angled shot of RJ-45 Ethernet Female Socket to Terminal Spring Block Adapter.
If you need to connect an RJ-45 cable (a.k.a Ethernet) to a board that doesn't have an Ethernet jack - this adapter will come in very handy! No soldering required -...
Hook-up Wire Spool Set in box with 6 colorful wires coming out
Perfect for bread-boarding, free wiring, etc. This box contains 6 spools of solid-core wire. The wire is easy to solder to and when bent it keeps its shape pretty well. We like to have...
close up of ends of various small heat shink tubes
Heat shrink is the duct tape of electronics, it keeps your stuff all safe and kept together. Especially when wiring and soldering, use heat shrink to add mechanical strength to cables....
Angel shot of the Grove to STEMMA QT / Qwiic / JST SH Cable
Are you a maker in the midst of a STEMMA dilemma? This 100mm long cable is...
  • Cut short sections of solid core hook-up wire, then strip their ends
  • Cut and slide the insulation to expose a section of wire in the middle
  • Bend each wire to form a tight U-shape
  • Insert each wire into the RJ-45 adapter as shown
  • Remove the Grove connector from a STEMMA QT-to-Grove adapter (or cut and strip the ends)
  • Slip short sections of heat shrink tubing over each STEMMA QT wire as shown below
  • Solder the STEMMA QT cable wires to the U-shaped jumpers as shown
  • Repeat for the other adapter

Slide the tubing over each solder junction and heat shrink it in place.

Now, you can plug in any length (up to about 100 feet / 30 meters seems to work well) of Ethernet cable, and then plug the STEMMA QT cables into your sensor on one end and the LTC4311 terminator on the other. Connect the LTC4311's other connector to your microcontroller and you're ready to go!

Some community members have suggested, "... (it may) be better to use 1 pair for ground and power, 1 pair for ground and clock and 1 pair for ground and data... It seems like this would mitigate EMI on the power and signal wires relative to ground." Try it out and see if you can get even longer runs of cable!

This guide was first published on Oct 07, 2020. It was last updated on Mar 08, 2024.

This page (Ethernet Breakout Usage) was last updated on Mar 08, 2024.

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