node-hid

node-hid - Access USB HID devices from node.js

Installation

Prerequisites:

• Mac OS (I use 10.6.8) or Linux (kernel 2.6+) or Windows XP+
• node.js v0.8
• libudev-dev (Linux only)
• libusb-1.0-0-dev (Ubuntu versions missing libusb.h only)
• git

Compile from source on Linux or OSX

Use npm to execute all installation steps:

npm install

Compile from source on Windows

Use node-gyp to compile the extension.

Please note that Windows support is incomplete and needs some work to pull it to the same level as on Linux and OSX. See issues #10 and #15 in github for discussion. Pull requests to improve Windows support would be welcome.

Test it

In the src/ directory, various JavaScript programs can be found that talk to specific devices in some way. The show-devices.js program can be used to display all HID devices in the system.

How to Use

Load the extension

var HID = require('node-hid');

Get a list of all HID devices in the system:

var devices = HID.devices()

devices will contain an array of objects, one for each HID device available. Of particular interest are the vendorId and productId, as they uniquely identify a device, and the path, which is needed to open a particular device.

Here is some sample output:

HID.devices();
[ { vendorId: 1452,
    productId: 595,
    path: 'USB_05ac_0253_0x100a148e0',
    serialNumber: '',
    manufacturer: 'Apple Inc.',
    product: 'Apple Internal Keyboard / Trackpad',
    release: 280,
    interface: -1 },
  { vendorId: 1452,
    productId: 595,
    path: 'USB_05ac_0253_0x100a14e20',
    serialNumber: '',
    manufacturer: 'Apple Inc.',
    product: 'Apple Internal Keyboard / Trackpad',
    release: 280,
    interface: -1 },
<and more>

Opening a device

Before a device can be read from or written to, it must be opened:

var device = new HID.HID(path);

device will contain a handle to the device. The path can be determined by a prior HID.devices() call. If an error occurs opening the device, an exception will be thrown.

Reading from a device

Reading from a device is performed by registering a "data" event handler:

device.on("data", function(data) {});

You can also listen for errors like this:

device.on("error", function(err) {});

All reading is asynchronous.

Writing to a device

Writing to a device is performed using the write call in a device handle. All writing is synchronous.

device.write([0x00, 0x01, 0x01, 0x05, 0xff, 0xff]);

Support

I can only provide limited support, in particular for operating systems and devices that I don't know. Please use the node-hid Google Group for general support inquiries ([e-mail]).

Complete API

var device = new HID.HID(path);

Event: "data"

• chunk - Buffer - the data read from the device

Event: "error"

• error - The error Object emitted

device.write(data)

• data - the data to be synchronously written to the device

device.close()

Closes the device. Subsequent reads will raise an error.

device.pause()

Pauses reading and the emission of data events.

device.resume()

This method will cause the HID device to resume emmitting data events. If no listeners are registered for the data event, data will be lost.

When a data event is registered for this HID device, this method will be automatically called.

device.read(callback)

Low-level function call to initiate an asynchronous read from the device. callback is of the form callback(err, data)