UART rx0 tx0 help needed

Hello !

I'm using a ramps FD and an ESP3D wired on RX1 TX1
I also have a Bigtreetech Touchscreen who also want to use an UART Port. Problem is When i connect the screen to RX0 TX0 it doesn't work... I can connect it to RX1 TX1 and esp3D to the screen but as soon as I do that the ESP3D can't be used anymore with repetier host and most of the wireless commands doesn't work anymore.
So this is the 1000$ question :smile: :
Why can't I use the port and how to enable communication on my arduino Due RX0 TX0 pins to connect the screen on theses pins and my ESP3D on RX1 TX1 ? (USB who normaly share the pins work like a charm)


  • RX0 TX0 is occupied by Programming port, that´s the reason.

  • Is there a way to use it anyway or redirect it to RX3 TX3 inside firmware ? I absolutely need two UART

  • edited July 2020
    why don´t you use serial2 or serial3 for your display?
    as i guess you have communication to repetier host via esp3d on serial one so you can use serial2 or 3 for your display.
    seems you don´t use native usb and programming port.

    simply add #define RFSERIAL Serial2 at beginning of configuration.h

    to redirect from programming port to Serial2

  • It worked !!! I've put serial 0 to serial 3 and my screen on it and the bluetooth on serial 1
    But now the screen became crazy with "checksum error" and beeps endlessly
  • Which device is having checksum errors? ESP3D or touchscreen? Anyhow that would be communication errors or they violate the communication protocol somehow. Is it every command and gets corrected or only quite frequent.
  • well, the esp3D commands are filtered by the screen who is made for marlin so you can't use it with repetier except for a few commands.
    when screen is on uart 3 and esp3D on UART1 the screen beep as hell with the error message "checksum error" endlessly before the communication even start since the esp isn't powered yet. the only solution is to physically disconnect the esp to get the screen back

  • what´s your firmware setting for uart3?
    do you use the bluetooth setting?
  • edited August 2020
    repetier 1.0.5
    Bluetooth = UART1 => Esp3D
    USB = UART3 =>Bigtreetech TFT V3 7"

    Motherboard Ramps FD with TMC5130 for XYZ and TMC 2130 for Dual extruders SPI Mode for both
    Laser 15W
    Steppers drivers + X&Y Motors + Laser + Print head watercooled
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