Drive pull-up Rx pin on TTL half duplex message
Posted: Thu Apr 07, 2022 3:52 pmHello,
I'm working on a project to drive a stove which is sending TTL half-duplex messages.
So I have the attached circuit. Unfortunately the pull-up resistance on the Rx pin of an esp8266 (Wemos D1 mini or NodeMCU Lolin v3) make me impossible to read data received from the stove.
If data are correctly at 3.3V, on the Rx pin it will only receive constant 3.3V, when I trick by applying 5V on received data, the Rx pin fluctuate between 5V and 3.3V (with correct message on it, but the esp isn't able to read it, and it's dangerous to have this 5V).
How can I proceed to have voltage between 3.3 and 0V ? And beeing able to read UART data on the Rx pin.
If you have any other idea on how to correctly received message from the stove to the Rx pin, I'm open to the discussion.
I'm working on a project to drive a stove which is sending TTL half-duplex messages.
So I have the attached circuit. Unfortunately the pull-up resistance on the Rx pin of an esp8266 (Wemos D1 mini or NodeMCU Lolin v3) make me impossible to read data received from the stove.
If data are correctly at 3.3V, on the Rx pin it will only receive constant 3.3V, when I trick by applying 5V on received data, the Rx pin fluctuate between 5V and 3.3V (with correct message on it, but the esp isn't able to read it, and it's dangerous to have this 5V).
How can I proceed to have voltage between 3.3 and 0V ? And beeing able to read UART data on the Rx pin.
If you have any other idea on how to correctly received message from the stove to the Rx pin, I'm open to the discussion.