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Serial Module Configuration

The serial module config options are: Enabled, Echo, Mode, Receive GPIO, Transmit GPIO and Sender. Serial Module config uses an admin message sending a ConfigModule.Serial protobuf.

This is a simple interface to send messages over the mesh network by sending strings over a serial port. Anything you send the node will be turned into a message sent out over the mesh, and anything received from the mesh will be sent to the serial port. Note that this module does not (yet) allow arbitrary protobuf commands to be sent over the serial connection.

Serial Module Config Values


Enables the serial module.


If set, any packets you send will be echoed back to your device.


Receive GPIO Pin

Set the GPIO pin to the RXD pin you have set up.

Transmit GPIO Pin

Set the GPIO pin to the RXD pin you have set up.


Connect the TX pin to the other device's RX pin, and vice versa. Connect their grounds to each other (not necessary if they're both plugged into the same USB power source.)

Baud Rate

The serial baud rate.


The amount of time to wait before we consider your packet as "done".


Once module settings are changed, a reset is required for them to take effect.

Serial Module Config Client Availability


All serial module config options are available on iOS, iPadOS and macOS at Settings > Modules > Serial.


GPIO access is fundamentally dangerous because invalid options can physically damage or destroy your hardware. Ensure that you fully understand the schematic for your particular device before trying this as we do not offer a warranty. Use at your own risk.

This module requires attaching a peripheral accessory to your device. It will not work without one.


Default is to use RX GPIO 16 and TX GPIO 17.

Basic Usage:

  1. Enable the module by setting serial_module_enabled to 1.
  2. Set the pins (serial.rxd / serial.txd) for your preferred RX and TX GPIO pins. On tbeam boards it is recommended to use:
    • RXD 35
    • TXD 15
  3. Set serial.timeout to the amount of time to wait before we consider your packet as "done".
  4. (Optional) In serial_module.h set the port to PortNum_TEXT_MESSAGE_APPif you want to send messages to/from the general text message channel.
  5. Connect to your device over the serial interface at 38400 8N1.
  6. Send a packet up to 240 bytes in length. This will get relayed over the mesh network.
  7. (Optional) Set serial_module_echo to 1 and any message you send out will be echoed back to your device.