TTL half-duplex messages through pull-up Rx pin

Using Arduino General Electronics
1

Hello,

I'm working on a project to drive a stove which is sending TTL half-duplex messages. So I'm using this circuit in between my stove and the esp8266 (Wemos D1 mini or NodeMCU Lolin v3) powered with the 5V from the stove (normally used to powered official the remote control when plugged):
image

Unfortunately, as the esp8266 have a internal pull-up on the Rx pin of the board, the communication stay at +3.3V instead of having correct 0 to 3.3V. So I'm not able to read the answer from the stove by this esp8266 board.

That's why I'm asking your support. Does someone have an idea on how to deal with this in order to be able to read correct reply from the stove on the esp8266 board ?

2

may be the answer of this (google translated) question might help ?

➜ Communication Série TTL half-duplex - Connexion Wemos D1 Mini et Poêle Ravelli par Frysko - page 1 - OpenClassrooms

3

As I understand it the motivation is to isolate Rx from own Tx. Why? You know what you are sending and you simply ignore those incoming data. Or even better: you check if the data were sent successfully or if there was a collision. Keep the diode and discard the rest.

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