arduino_serial_led

int ledPin = 13;
String cmd = "";
String tmpCmd = "";
boolean readCmd = false;
void setup () {
  Serial.begin (9600);
  pinMode(ledPin, OUTPUT);
}

void loop () {
  while (Serial.available()) {
    char c = Serial.read();
    if(c == '$' && !readCmd) {
      readCmd = true;
      cmd = tmpCmd;
      tmpCmd = "";
    }
    else {
      tmpCmd += c;
    }
    if(readCmd) {
      if(cmd == "LED13") {
        Serial.println("LED ON");
        digitalWrite(ledPin, HIGH);
        delay(500);
        digitalWrite(ledPin, LOW);
      } else {
        Serial.println("Got:"  + cmd);
      }
      readCmd = false;
      cmd = "";
    }
    
  }
}

nodejs

console.log("Starting");
var serialport = require("serialport");
var SerialPort = serialport.SerialPort;


process.stdin.resume();
process.stdin.setEncoding('utf8');	
var util = require('util');



// list serial ports:
serialport.list(function (err, ports) {
	ports.forEach(function(port) {
		console.log(port.comName);
	});
});

var myPort = new SerialPort("/dev/ttyACM0", {
	baudRate: 9600,
   // look for return and newline at the end of each data packet:
   parser: serialport.parsers.readline("\n")
});

function saveLatestData(data) {
	console.log("Serial data: " + data);
}

function showPortClose() {
	console.log('port closed.');
}

function showPortOpen() {
	console.log('port opened');
	myPort.write(process.argv[2]+"$");
}

function showError(error) {
	console.log('Serial port error: ' + error);
}


myPort.on('open', showPortOpen);
myPort.on('data', saveLatestData);
myPort.on('close', showPortClose);
myPort.on('error', showError);