ESP32-S3-Touch-LCD-7 RS485 question

2025-09-06 09:43:55 Ask

Does anyone know how the the RS485 driver IC circuit (U6) works on the Waveshare ESP32-S3-Touch-LCD-7 PCB?

The UART TX pin from ESP32 is connected to RO (receiver output). So what prevents damage from connecting two outputs together?

ESP32-S3-Touch-LCD-7 RS485 driver IC question

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SpotPearGueste93f8

Answer time:2025-09-06 13:38:39

SP3485EN is a half-duplex RS485 transceiver, which can either operate in transmitter mode or receiver mode at the same time; it cannot perform both simultaneously. The switching is controlled by the chip's DE/RE pin.

In receiver mode: the RO pin becomes an active output, and it sends data from the bus to the ESP32. The software must configure the UART TX pin as input mode to receive data from RO.

In transmitter mode: the RO pin is in a high-impedance state. At this time, the UART TX pin of the ESP32 is an output pin that sends data to the DI pin of U6. The RO pin appears as if it does not exist, so there is no conflict between the two outputs.

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SpotPearGuest2d69c

Answer time:2025-11-14 05:51:51

I am having trouble to have the RS485 working. I can send data, but cannot receive anything...I checked the pins, are ok, but, the sample software to receive data by rs485 and send the same data by rs485 is not working...I spent some hours to debug, but not found the problem...To send ok, to receive not ok...Could please someone give some support about it ?

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ESP32-S3-Touch-LCD-7 RS485 question

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