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chrome-apps-serialport

The chrome-apps-serialport JavaScript module is a Chrome Apps-compatible implementation of the node-serialport module used for serial communication.

This library was created to provide Chrome Apps (including NW.js) interoperability for libraries already depending on the node-serialport module for serial communication (e.g. johnny-five, firmata, etc.).

NW.js Support

The main use case for this library is to simplify usage of Johnny-Five and Firmata inside NW.js. While node-serialport can be used within NW.js, it needs to be specifically recompiled. This can prove to be troublesome. This library bypasses this problem by using the chrome.serial API which is already available in NW.js (via the builtin support for the Chrome Apps APIs).

The chrome-apps-serialport module also fixes a long-standing issue in NW.js that must be dealt with in order to successfully use the serial port. This means that, if you use this module, you do not need to bother importing the nwjs-j5-fix module. It will be taken care of for you.

Installation

npm install chrome-apps-serialport

Basic Usage

const SerialPort = require("chrome-apps-serialport").SerialPort;

let port = new SerialPort("/dev/tty-usbserial1", {
  baudrate: 57600
});

Using the module with Johnny-Five

const SerialPort = require("chrome-apps-serialport").SerialPort;
const Firmata = require("firmata-io")(SerialPort);
const five = require("johnny-five");

SerialPort.list().then(ports => {

  const device = ports.find(port => {
    return port.manufacturer && port.manufacturer.startsWith("Arduino")
  });

  const board = new five.Board({
    io: new Firmata(device.path)
  });

  board.on("ready", () => {
    console.log("Johnny-Five is ready!");
    const led = new five.Led(13);
    led.blink(500);
  });

  board.on("close", () => console.log("Closed!"));

});

History

The chrome-apps-serialport module is a repackaging of browser-serialport (created by Glen Arrowsmith). This module was working great until API changes were introduced in version 8 of node-serialport. These changes forced dependent projects to update which, in turnm broke compatibility with browser-serialport. Since browser-serialport has not been updated in many years, I packaged chrome-apps-serialport to insure compatibility with the latest version of node-serialport.

Compatibility

Unless you are using very specialized functionalities (see below), you should be able to use chrome-apps-serialport wherever node-serialport v8.x+ is used. Obviously, this is only true if you are executing the code within a Chrome App or NW.js.

Due to the underlying architecture (chrome.serial), there are a few differences that should be noted:

  • The connection options are a little bit different:

    • dataBits: 7, 8
    • stopBits: 1, 2
    • parity: 'none', 'even', 'mark', 'odd', 'space'
    • flowControl: 'RTSCTS'
    • highWaterMark: ignored
    • lock: ignored
    • xon, xoff, xany: ignored

  • Parsers are not implemented.

  • The read() method is not implemented.

  • The drain() method can be called but will not do anything. This also means that no drain events are ever dispatched.

  • Only UTF8 is supported when passing strings to the write() method.

  • Error messages differ.