Intercept RJ45 connector to emulate key events on Standing desk controller (TiMotion TC16)

distante · May 13, 2024, 11:16am

I have an Standing Desk (height adjustable desk) that is controlled by this:

It has an RJ45 cable at the end that goes into the the desk control box

For what I have found, this is the official page of that controller https://www.timotion.com/en/products/control-boxes/tc16-series

I am searching for a way to integrate it into home assistant while keeping the “offline” functionality as it is.

My first idea was to buy something like this and connect it to an ESP32 board with ESPhome from where I can emulate the same button press that are done in the keypad.

That said, maybe I am being naive about how that thing works. Did anyone have done something similar?

Cheers!

WallyR · May 13, 2024, 1:37pm

You misunderstand the merger/splitter plug you have found.
Normally an ethernet cable only use wire 1+2 and 4+5 of the 8 wires available.
The merger/splitter plug will move wire 1+2 to 7+8 and 4+5 to 3+6 for one of the two connectors, thereby utilizing all 8 wires on the cable connected to the side with only 1 connector and later using the same plug to again split them out into two normal ethernet connectors.

In other words, for both connectors on the side with 2 connectors there will be no connection on wire 3,6,7 and 8.

aceindy · May 13, 2024, 1:43pm

That said, the RJ45 connector most likely doesn’t even use a LAN signal, but just uses the 8 wires (or some of them) to control/feedback the actuator…

Did some searching…is this interesting?

WallyR · May 13, 2024, 1:56pm

If the RJ45 connector is the only one connected to the button panel, then it is not that simply anymore.
You have 7 buttons and numbers and maybe even lights too.
With only 8 wires available it requires more than just a shorted wire here and there to make it work.

distante · May 13, 2024, 2:53pm

ahh!! I knew it could not be that easy thanks for the explanation

distante · May 13, 2024, 2:59pm

This looks interesting. Thank you for it. I did not used the correct search terms.

Mahko_Mahko · May 13, 2024, 8:13pm

In the case of the Desky project, it uses both uart on one wire (for one way comms from controller to control panel) and shorts other wires (for control from panel to controller)!

This project might give you some structure for how to get started.

Doing a teardown of both controller and handset and posting photos, measuring voltages on wires on the handset side (probably accessible), pulling out the logic analyser, and setting up a ESPHome uart debug to try to read uart messages on wires are all good places to start.

This post shows how you can physically build a “pass through” type set-up (similar to your idea about the splitter) using an rj45 breakout.