node-ble

Bluetooth Low Energy (BLE) library written with pure Node.js (no bindings) - baked by Bluez via DBus

Setup

yarn add node-ble

Example

Provide permissions

In order to allow a connection with the DBus daemon, you have to set up right permissions.

Create the file /etc/dbus-1/system.d/node-ble.conf with the following content (customize with userid)

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
  "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <policy user="%userid%">
   <allow own="org.bluez"/>
    <allow send_destination="org.bluez"/>
    <allow send_interface="org.bluez.GattCharacteristic1"/>
    <allow send_interface="org.bluez.GattDescriptor1"/>
    <allow send_interface="org.freedesktop.DBus.ObjectManager"/>
    <allow send_interface="org.freedesktop.DBus.Properties"/>
  </policy>
</busconfig>

STEP 1: Get Adapter

To start a Bluetooth Low Energy (BLE) connection you need a Bluetooth adapter.

const {createBluetooth} = require('node-ble')
const {bluetooth, destroy} = createBluetooth()
const adapter = await bluetooth.defaultAdapter()

STEP 2: Start discovering

In order to find a Bluetooth Low Energy device out, you have to start a discovery operation.

if (! await adapter.isDiscovering())
  await adapter.startDiscovery()

STEP 3: Get a device, Connect and Get GATT Server

Use an adapter to get a remote Bluetooth device, then connect to it and bind to the GATT (Generic Attribute Profile) server.

const device = await adapter.waitDevice('00:00:00:00:00:00')
await device.connect()
const gattServer = await device.gatt()

STEP 4a: Read and write a characteristic.

const service1 = await gattServer.getPrimaryService('uuid')
const characteristic1 = await service1.getCharacteristic('uuid')
await characteristic1.writeValue(Buffer.from("Hello world"))
const buffer = await characteristic1.readValue()
console.log(buffer)

STEP 4b: Subscribe to a characteristic.

const service2 = await gattServer.getPrimaryService('uuid')
const characteristic2 = await service2.getCharacteristic('uuid')
await characteristic2.startNotifications()
characteristic2.on('valuechanged', buffer => {
  console.log(buffer)
})
await characteristic2.stopNotifications()

STEP 5: Disconnect

When you have done you can disconnect and destroy the session.

await device.disconnect()
destroy()

Reference

const {createBluetooth} = require('node-ble')
const {bluetooth, destroy} = createBluetooth()

| Method | Description | | --- | --- | |Bluetooth bluetooth | |void destroy() |

Bluetooth

| Method | Description | | --- | --- | | Promise<String[]> adapters() | List of available adapters | | Promise<Adapter> defaultAdapter() | Get an available adapter | | Promise<Adapter> getAdapter(String adapter) | Get a specific adapter (one of available in adapters())|

Adapter

| Method | Description | | --- | --- | | Promise<String> getAddress() | The Bluetooth device address. | | Promise<String> getAddressType()| The Bluetooth Address Type. One of public or random. | | Promise<String> getName()| The Bluetooth system name (pretty hostname). | | Promise<String> getAlias()| The Bluetooth friendly name. | | Promise<bool> isPowered()| Adapter power status. | | Promise<bool> isDiscovering()| Indicates that a device discovery procedure is active. | | Promise<void> startDiscovery()| Starts the device discovery session. | | Promise<void> stopDiscovery()| Cancel any previous StartDiscovery transaction. | | Promise<String[]> devices()| List of discovered Bluetooth Low Energy devices | | Promise<Device> getDevice(String uuid)| Returns an available Bluetooth Low Energy (waitDevice is preferred)| | Promise<Device> waitDevice(String uuid)| Returns a Bluetooth Low Energy device as soon as it is available | | Promise<String> toString()| User friendly adapter name |

Device extends EventEmitter

| Method | Description | | --- | --- | | Promise<String> getName() | The Bluetooth remote name. | | Promise<String> getAddress() | The Bluetooth device address of the remote device. | | Promise<String> getAddressType() | The Bluetooth Address Type. One of public or random. | | Promise<String> getAlias() | The name alias for the remote device. | | Promise<String> getRSSI() | Received Signal Strength Indicator of the remote device. | | Promise<String> isPaired() | Indicates if the remote device is paired. | | Promise<String> isConnected() | Indicates if the remote device is currently connected. | | Promise<void> pair() | Connects to the remote device, initiate pairing and then retrieve GATT primary services (needs a default agent to handle wizard).| | Promise<void> cancelPair() | This method can be used to cancel a pairing operation initiated by the Pair method. | | Promise<void> connect() | This is a generic method to connect any profiles the remote device supports that can be connected to and have been flagged as auto-connectable on our side. | | Promise<void> disconnect() | This method gracefully disconnects all connected profiles and then terminates low-level ACL connection. | | Promise<GattServer> gatt() | Waits services resolving, then returns a connection to the remote Gatt Server | Promise<String> toString() | User friendly device name. |

| Event | Description | | --- | --- | | connect | Connected to device | | disconnect | Disconnected from device |

GattServer

| Method | Description | | --- | --- | | Promise<String[]> services() | List of available services | | Promise<GattService> getPrimaryService(String uuid) | Returns a specific Primary Service |

GattService

| Method | Description | | --- | --- | | Promise<bool> isPrimary() | Indicates whether or not this GATT service is a primary service. | | Promise<String> getUUID() | 128-bit service UUID. | | Promise<String[]> characteristics() | List of available characteristic UUIDs. | | Promise<GattCharacteristic> getCharacteristic(String uuid) | Returns a specific characteristic. | | Promise<String> toString() | User friendly service name. |

GattCharacteristic extends EventEmitter

| Method | Description | | --- | --- | | Promise<String> getUUID() | 128-bit characteristic UUID. | | Promise<String[]> getFlags() | Defines how the characteristic value can be used. | | Promise<bool> isNotifying() | True, if notifications or indications on this characteristic are currently enabled. | | Promise<Buffer> readValue(Number offset = 0) | Issues a request to read the value of the characteristic and returns the value if the operation was successful. | | Promise<void> writeValue(Buffer buffer, Number offset = 0) | Issues a request to write the value of the characteristic. | | Promise<void> startNotifications() | Starts a notification session from this characteristic if it supports value notifications or indications. | | Promise<void> stopNotifications() | This method will cancel any previous StartNotify transaction. | | Promise<String> toString() | User friendly characteristic name. |

| Event | Description | | --- | --- | | valuechanged | New value is notified. (invoke startNotifications() to enable notifications)

Compatibility

This library works on many architectures supported by Linux. It leverages on Bluez driver, a component supported by the following platforms and distributions https://www.bluez.org/about

Node-ble has been tested on the following environment:

• Raspbian GNU/Linux 10 (buster)
• Ubuntu 18.04.4 LTS

Changelog

• 0.x - Beta version
• 1.0 - First official version
• 1.1 - Migrates to gh-workflows
• 1.2 - Upgrades deps

Contributors

• chrvadala (author)

Run tests

In order to run test suite you have to set up right DBus permissions.

Create the file /etc/dbus-1/system.d/node-ble-test.conf with the following content (customize with userid)

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
  "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <policy user="%userid%">
    <allow own="org.test"/>
    <allow send_destination="org.test"/>
    <allow send_interface="org.test.iface"/>
  </policy>
</busconfig>

Unit tests

yarn test

End to end (e2e) tests

The end to end test will try to connect to a real bluetooth device and read some characteristics. To do that, you need two different devices.

Device 1

wget https://git.kernel.org/pub/scm/bluetooth/bluez.git/plain/test/example-advertisement
wget https://git.kernel.org/pub/scm/bluetooth/bluez.git/plain/test/example-gatt-server
python example-advertisement
python example-gatt-server
hcitool dev #this command shows bluetooth mac address

Device 2

# .env
TEST_DEVICE=00:00:00:00:00:00
TEST_SERVICE=12345678-1234-5678-1234-56789abcdef0
TEST_CHARACTERISTIC=12345678-1234-5678-1234-56789abcdef1
TEST_NOTIFY_SERVICE=0000180d-0000-1000-8000-00805f9b34fb
TEST_NOTIFY_CHARACTERISTIC=00002a37-0000-1000-8000-00805f9b34fb

yarn test:e2e

References

• https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/adapter-api.txt
• https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/device-api.txt
• https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/gatt-api.txt
• https://webbluetoothcg.github.io/web-bluetooth - method signatures follow, when possible, WebBluetooth standards
• https://developers.google.com/web/updates/2015/07/interact-with-ble-devices-on-the-web - method signatures follow, when possible, WebBluetooth standards

Similar libraries

• https://github.com/noble/noble
• https://github.com/abandonware/noble (noble fork)
• https://www.npmjs.com/package/node-web-bluetooth

Useful commands

| Command | Description | | --- | --- | | rm -r /var/lib/bluetooth/* | Clean Bluetooth cache | | hciconfig -a | Adapter info | | hcitool dev | Adapter info (through Bluez) | | d-feet | DBus debugging tool | | nvram bluetoothHostControllerSwitchBehavior=never | Only on Parallels |