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    ESP32 and RS485

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    • A Offline
      alex9
      last edited by

      Hi,

      I'm trying to use the RS485 interface on the M5Stack StampPLC (ESP32-S3 based) to transmit a test signal

      Problem:

      GPIO 0 measures 0V with a multimeter (should be 3.3V idle for UART)
      No signal appears on the oscilloscope — only millivolt noise
      Serial Monitor shows nothing (USB-CDC may not be configured)

      Questions:
      -Is GPIO 0 the correct TX pin for RS485 on StampPLC, or does it have a different pinout?

      -What are the correct build_flags in platformio.ini to enable USB-CDC on the ESP32-S3 variant used in StampPLC?

      -Is there an official StampPLC Arduino/PlatformIO example for RS485 communication?

      felmueF 1 Reply Last reply Reply Quote 0
      • felmueF Offline
        felmue @alex9
        last edited by felmue

        Hello @alex9

        it looks like yes, GPIO0 is TX pin for RS485. See pinmap here.

        The platformio.ini example can be found here.

        Running a quick search I did not find an RS485 example, sorry.

        Edit: Maybe try this RS485 library.

        Thanks
        Felix

        GPIO translation table M5Stack / M5Core2
        Information about various M5Stack products.
        Code examples

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