Serial Plotter WebApp

This is a SPA that receives data points over WebSocket and prints graphs. The purpose is to provide a visual and live representation of data printed to the Serial Port.

The application is designed to be as agnostic as possible regarding how and where it runs. For this reason, it accepts different settings when it's launched in order to configure the look&feel and the connection parameters.

Main Tech/framework used

• React: as the backbone of the application
• Chart.js: to display data
• WebSockets: to provide a fast communication mechanism between a middle layer and the Serial Plotter (see section How it works)
• Npm: as the registry

How it works

• As soon as the application is bootstrapped it reads the URL parameters and uses them to set the initial state and create the WebSocket connection
• When the WebSocket connection is created, data points are collected, parsed, and printed to the chart
• The app can also send messages back to the boards via WebSocket

Config Parameters

The Serial Plotter Web App is initialized by passing a number of parameters in the URL, in the form of a QueryString (eg: http://localhost:3000?currentBaudrate=2400&baudrates=300,1200,2400,4800,9600,19200,38400,57600,74880,115200,230400,250000,500000,1000000,2000000&darkTheme=true&wsPort=5000&connected=true&interpolate=true&generate=true).

Name	Description	Type (default)
currentBaudrate	currently selected baudrate	Number(9600)
currentLineEnding	currently selected line ending	String("\r\n")
baudrates	populate the baudrates menu	String[]/Comma separated strings ([])
darkTheme	whether to use the dark version of the plotter	Boolean(false)
wsPort	websocket port used for communication	Number(3030)
interpolate	whether to smooth the graph or not	Boolean(false)
serialPort	name of the serial port the data is coming from	String("")
connected	whether if the serial port is connected or not	Boolean(false)
generate	generate fake datapoints to print random charts (dev purposes only)	Boolean(false)

It is possible to update the state of the serial plotter by sending the above parameters via WebSocket in the form of a JSON-stringified object, using the MIDDLEWARE_CONFIG_CHANGED Command.

Websocket Communication Protocol

Besides the initial configuration, which is passed in via URL parameters, the communication between the app and the middleware is implemented over WebSocket.

It's possible to send a JSON-stringified message from and to the Serial Plotter App, as long as it adheres to the following format:

{
  "command": <a valid command, see below>,
  "data": <the value for the command>
}

The command/data fields follow the specification:

Command Field	Data field format	Initiator	Description
"PLOTTER_SET_BAUDRATE"	number	Serial Plotter	request the middleware to change the baudrate
"PLOTTER_SET_LINE_ENDING"	string	Serial Plotter	request the middleware to change the lineending for the messages sent from the middleware to the board
"PLOTTER_SEND_MESSAGE"	text	Serial Plotter	send a message to the middleware. The message will be sent over to the board
"PLOTTER_SET_INTERPOLATE"	boolean	Serial Plotter	send the interpolation flag to the Middleware
"MIDDLEWARE_CONFIG_CHANGED"	Object (see config parameters )	Middleware	Send an updated configuration from the middleware to the Serial Plotter. Used to update the state, eg: changing the color theme at runtime

Example of a message ready to be sent from the Serial Plotter App to the Middleware

const websocketMessage = JSON.stringify({command: "PLOTTER_SET_BAUDRATE", data: 9600})

NOTE: For performance sake, the raw data coming from the serial port that is sent by the middleware to the serial plotter has to be a stringified array of values, rather than the Command/Data object

Development

• npm i to install dependencies
• npm start to run the application in development mode @ http://localhost:3000

Deployment

Usually, there is no need to build the app manually: as soon as a new version of the package.json is merged into main branch, the CI runs and deploys the package to npm.

Security

If you think you found a vulnerability or other security-related bug in this project, please read our security policy and report the bug to our Security Team 🛡️ Thank you!

e-mail contact: security@arduino.cc