WebSerial is a minimal Electron application to bring Serial communication to Web browsers through websockets.
Web MIDI, Web Bluetooth and Web USB are awesome ways to connect physical devices and microcontrollers to Web browsers and create rich interactive experiments.
But, while these APIs are still in early stages, not widely supported or limited to a very little set of devices for now, WebSockets are way more accessible and cheap Arduinos or the likes can be found easily.
WebSerial is a really simple way to connect your browser to any device with Serial communication and hack into physical web.
WebSerial provides two ways communication between Serial devices and browsers:
Serial data is forwarded to your page, and you can also use it to send data from your web page to your device.
WebSerial uses serialport to open a Serial connection, and runs an express / socket.io websocket server to communicate with your web page in realtime.
Server runs on port 8135 by default but can be changed in WebSerial.
For references, see:
- https://caniuse.com/#feat=midi
- https://caniuse.com/#feat=web-bluetooth
- https://caniuse.com/#feat=webusb
- https://caniuse.com/#feat=mdn-api_websocket
WebSerial uses the \n character as a delimiter to parse data.
In Arduino, this corresponds to use Serial.println().
void setup(){
Serial.begin(9600);
}
void loop() {
Serial.print(analogRead(A0));
Serial.print(',');
Serial.println(analogRead(A1));
delay(10);
}WebSerial also appends a \n character to your data, in order to parse it easily.
Check the Read ASCII String tutorial on Arduino's website.
Click here for some utility functions for parsing data in Arduino
#define MAX_CHARS 200
String input;
void setup() {
Serial.begin(9600);
input.reserve(MAX_CHARS);
}
void loop() {}
void serialEvent() {
while (Serial.available()) {
readChar();
}
}
void readChar() {
char c = (char) Serial.read();
Serial.print("->");
Serial.println(c);
}
void readString() {
char c = (char) Serial.read();
if (c == '\n') {
Serial.println("->" + input);
input = "";
}
else {
input += c;
}
}
void readInt() {
int i = Serial.parseInt();
Serial.print("->");
Serial.println(i);
}
void readLong() {
char c = (char) Serial.read();
if (c == '\n') {
char buffer[MAX_CHARS];
input.toCharArray(buffer, 20);
long l = atol(buffer);
Serial.print("->");
Serial.println(l);
input = "";
}
else {
input += c;
}
}- Download the latest release for your OS.
- Start the WebSerial application.
- Connect your Serial device.
- Select the
portandbaudratefor your device, and clickconnect. - On your web page, include the
webserial.jslibrary, or use this one (served via github pages):<script src="https://makio135.com/webserial/client/webserial.min.js"></script>
You now have access to the Webserial Class, see Documentation below 👇.
The Webserial Class needs to be instanciated:
const serial = new WebSerial()The constructor can take an options Object to define the following properties:
host: The IP of the computer running the WebSerial app. String, default tolocalhost, optional.port: The port of the websocket server. Number, default to8135, optional.log: Additional logs in the console for debugging. Boolean, default tofalse, optional.
const serial = new WebSerial({
host: '192.168.0.14',
port: 8000,
log: true
})A WebSerial Instance exposes a few methods and properties:
.on(eventName, callback), valid events are:'connect': no argument is passed to the callback'disconnect': no argument is passed to the callback'data': callback takes one argument, the data received
.write(dataString): method used to send data to the microcontrolller
<body>
<script src="js/webserial.min.js"></script>
<script>
const serial = new WebSerial()
serial.on('connect', () => console.log('Serial connected'))
serial.on('disconnect', () => console.log('Serial disconnected'))
serial.on('data', data => console.log(`Data received: ${data}`))
document.body.addEventListener('click', () => serial.write('Hello WebSerial'))
</script>
</body>Or for use in a more direct mode:
.isConnected: state of the connection with Serial (Boolean).data: last data received from Serial (String)
<!-- Example using the p5js library (https://p5js.org/) -->
<body>
<script src="js/webserial.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/p5@0.10.2/lib/p5.js"></script>
<script>
let serial = new WebSerial()
function setup(){
createCanvas(windowWidth, windowHeight);
background(0)
}
function draw(){
if(serial.isConnected && serial.data) {
let [r, g] = serial.data.split(',').map(d => parseInt(d) / 4)
background(r, g, 127)
}
}
function mousePressed() {
serial.write(int(mouseX / width * 255))
}
</script>
</body>WebSerial would not be possible without these great projects:
🙏🙏🙏