---
id: serial-plugin
title: Serial communication plugin
sidebar_label: Serial communication
---

## 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 plugin by setting `serialplugin_enabled` to `1`.
2. Set the pins (`serialplugin_rxd` / `serialplugin_rxd`) for your preferred RX and TX GPIO pins. On tbeam boards it is recommended to use:
    * RXD 35
    * TXD 15
3. Set `serialplugin_timeout` to the amount of time to wait before we consider your packet as "done".
4. (Optional) In SerialPlugin.h set the port to `PortNum_TEXT_MESSAGE_APP`if 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 `serialplugin_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 plugin 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 plugin 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.