// arduino_serial.js
// kll node + serial 
// start with:  node arduino_serial.js 
//         or:  node arduino_serial.js /dev/ttyACM0


'use strict';

const serialport = require('serialport');// include the library
const SerialPort = serialport.SerialPort; // make a local instance of it
   // get port name from the command line / or use default
var portName = "/dev/ttyACM0";
var portNameCLI = process.argv[2];
   console.log("port from command line:" + portNameCLI);
   if ( portNameCLI > "") { portName = portNameCLI; console.log(" used "); } else { console.log(" use default "); }


var serialData = 0;                    // latest data saved from the serial port


/* 
// good for test, but it not say if in use or not
// list serial ports:
serialport.list(function (err, ports) {
  ports.forEach(function(port) {
    console.log(port.comName);
  });
});
*/

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


// these are the definitions for the serial events:
myPort.on('open', showPortOpen);
myPort.on('data', saveLatestData);
myPort.on('close', showPortClose);
myPort.on('error', showError);

// the functions called when the serial events occur:
function showPortOpen() {
  console.log('port open:' + portName +' Data rate: ' + myPort.options.baudRate);
}

function saveLatestData(data) {
  console.log(data);    // show while develop
  serialData = data;
}

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

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