Arduino and Node.js via Serial port

Writing to serial in Arduino, reading from node.js

void setup() {
Serial.begin(9600); // Starts the serial communication
void loop() {
Serial.println("hello from arduino!");
const SerialPort = require('serialport');
const Readline = require('@serialport/parser-readline');
const port = new SerialPort('/dev/ttyACM0', { baudRate: 9600 });
const parser = port.pipe(new Readline({ delimiter: '\n' }));
// Read the port data
port.on("open", () => {
console.log('serial port open');
parser.on('data', data =>{
console.log('got word from arduino:', data);
  • In order to use serialport you have to npm install serialport it.
  • You will have to find the name of the serial port in your computer. An easy way to do this is from Arduino IDE, tools > port menu.
  • Make sure to use the same baud rate as the arduino (defined in setup function).
  • Since we used Serial.println (print line), we used the \n delimiter in the Readline parser.
  • Notice how we subscribe to the data event on the parser, and not the port directly.

Reading from the serial in arduino

  1. define a max length for your messages.
  2. define a 1 character long message separator. ie: ‘\n’
  port.write('hello from node\n', (err) => {
if (err) {
return console.log('Error on write: ', err.message);
console.log('message written');
const byte DATA_MAX_SIZE = 32;
char data[DATA_MAX_SIZE]; // an array to store the received data
void receiveData() {
static char endMarker = '\n'; // message separator
char receivedChar; // read char from serial port
int ndx = 0; // current index of data buffer
// clean data buffer
memset(data, 32, sizeof(data));
// read while we have data available and we are
// still receiving the same message.
while(Serial.available() > 0) {
receivedChar =; if (receivedChar == endMarker) {
data[ndx] = '\0'; // end current message
// looks like a valid message char, so append it and
// increment our index
data[ndx] = receivedChar;
// if the message is larger than our max size then
// stop receiving and clear the data buffer. this will
// most likely cause the next part of the message
// to be truncated as well, but hopefully when you
// parse the message, you'll be able to tell that it's
// not a valid message.
if (ndx >= DATA_MAX_SIZE) {
// no more available bytes to read from serial and we
// did not receive the separato. it's an incomplete message!
Serial.println("error: incomplete message");
memset(data, 32, sizeof(data));




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