meshtastic/docs/software/modules/serial.md

id	title	sidebar_label
serial-module	Serial communication module	Serial communication

import PluginModule from '@site/docs/_blocks/_plugin_module.mdx';

About

This is a simple interface to send messages over the mesh network by sending strings over a serial port.

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_module_rxd / serial_module_rxd) for your preferred RX and TX GPIO pins. On tbeam boards it is recommended to use:
   • RXD 35
   • TXD 15
3. Set serial_module_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.

:::note The device must be restarted after the settings have been changed for the module to take effect. :::

TODO (in this order):

• Define a verbose RX mode to report on mesh and packet information.

:::note This won't happen any time soon. :::

Known Problems

• Until the module is initialized by the startup sequence, the TX pin is in a floating state. Device connected to that pin may see this as "noise".
• Will not work on NRF and the Linux device targets.