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 your 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="yourusername">
   <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
`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<Buffer> 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)

Run tests

Unit tests

yarn test

End to end (e2e) tests

PC 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

PC 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

<!-- /etc/dbus-1/system.d/node-ble-test.conf -->
<!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="my_username">
    <allow own="org.test"/>
    <allow send_destination="org.test"/>
    <allow send_interface="org.test.iface"/>
  </policy>
</busconfig>

yarn test:e2e

Changelog

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

Contributors

buildog (author)

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

Useful commands

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

build-ble

node-ble

Setup

Example

Provide permissions

STEP 1: Get Adapter

STEP 2: Start discovering

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

STEP 4a: Read and write a characteristic.

STEP 4b: Subscribe to a characteristic.

STEP 5: Disconnect

Reference

Bluetooth

Adapter

Device extends EventEmitter

GattServer

GattService

GattCharacteristic extends EventEmitter

Run tests

Unit tests

End to end (e2e) tests

PC 1

PC 2

Changelog

Contributors

References

Similar libraries

Useful commands

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