bleno

A Node.js module for implementing BLE (Bluetooth Low Energy) peripherals.

Need a BLE central module? See @stoprocent/noble.

About This Fork

This fork of bleno was created to introduce several key improvements and new features:

1. HCI UART Support: This version enables HCI UART communication through the @stoprocent/node-bluetooth-hci-socket dependency, allowing more flexible use of Bluetooth devices across platforms.

2. Multi-Connection Support: Added support for multiple concurrent BLE central connections, allowing the peripheral to handle several connected devices simultaneously. This enables scenarios where multiple clients can connect and interact with the peripheral at the same time.

3. macOS Native Bindings Fix: I have fixed the native bindings for macOS, ensuring better compatibility and performance on Apple devices.

4. Modern Async API: Added Promise-based async methods for all major operations, making it easier to use with modern JavaScript/TypeScript applications.

5. TypeScript Support: Full TypeScript definitions included for better development experience and type safety.

6. New Features: A setAddress function has been added, allowing users to set the MAC address of the peripheral device. Additionally, I plan to add raw L2CAP channel support, enhancing low-level Bluetooth communication capabilities.

If you appreciate these enhancements and the continued development of this project, please consider supporting my work.

Install

npm install @stoprocent/bleno --save

Usage

TypeScript

import bleno from "@stoprocent/bleno";

JavaScript

const bleno = require('@stoprocent/bleno');

See examples folder for code examples.

Prerequisites

Import

Binding will be picked automatically

import bleno from "@stoprocent/bleno";

Binding picked manually

import { withBindings } from "@stoprocent/bleno";

const bleno = withBindings('default');
const bleno = withBindings('mac');
const bleno = withBindings('hci', { hciDriver: '...', bindParams: ... });

For available hciDriver: DriverType and bindParams: BindParams please refer to @stoprocent/bluetooth-hci-socket interface.

UART (Any OS)

Please refer to https://github.com/stoprocent/node-bluetooth-hci-socket#uartserial-any-os

Example 1 (UART port specified as environmental variable)

$ export BLUETOOTH_HCI_SOCKET_UART_PORT=/dev/tty...
$ export BLUETOOTH_HCI_SOCKET_UART_BAUDRATE=1000000

NOTE: BLUETOOTH_HCI_SOCKET_UART_BAUDRATE defaults to 1000000 so only needed if different.

const bleno = require('@stoprocent/bleno');

Example 2 (UART port specified in bindParams)

import { withBindings } from "@stoprocent/bleno";

const bleno = withBindings('hci', { 
    hciDriver: 'uart', 
    bindParams: { 
        uart: { 
            port: '/dev/cu.usbserial-1420' 
        } 
    } 
});

await bleno.waitForPoweredOnAsync(1000); // Timeout of 1s
await bleno.startAdvertisingAsync('hello', ['d00d', 'b00b']);

Multi-Connection Support

This fork of bleno supports multiple concurrent BLE central connections, allowing several clients to connect to your peripheral simultaneously.

The library automatically restarts advertising after accepting a connection, enabling seamless multi-client connectivity by default. If you want to prevent additional connections, you can explicitly stop advertising in the accept callback:

// Default behavior - allows multiple connections
bleno.on('accept', async (address, handle) => {
  console.log(`New connection accepted: ${address}, handle: ${handle}`);
  // Advertising automatically continues - no action needed
});

// Optional: Stop additional connections
bleno.on('accept', async (address, handle) => {
  console.log(`New connection accepted: ${address}, handle: ${handle}`);
  // Explicitly stop advertising if you want to prevent additional connections
  await bleno.stopAdvertisingAsync();
});

If you stop advertising, you'll need to manually restart it after the last client disconnects to keep the device connectable.

bleno.on('disconnect', async (address, handle) => {
  console.log(`Client disconnected: ${address}, handle: ${handle}`);
  // Only need to restart advertising if you explicitly stopped it
  // await bleno.startAdvertisingAsync('my-device', ['service-uuid']);
});

OS X

• install the XCode command line tools via xcode-select --install
• 10.9 or later

Linux

• Kernel version 3.6 or above
• libbluetooth-dev
• bluetoothd disabled, if BlueZ 5.14 or later is installed. Use sudo hciconfig hci0 up to power Bluetooth adapter up after stopping or disabling bluetoothd.
  • System V:
    • sudo service bluetooth stop (once)
    • sudo update-rc.d bluetooth remove (persist on reboot)
  • systemd
    • sudo systemctl stop bluetooth (once)
    • sudo systemctl disable bluetooth (persist on reboot)

If you're using noble and bleno at the same time, connected BLE devices may not be able to retrieve a list of services from the BLE adaptor. Check out noble's documentation on bleno compatibility

Ubuntu/Debian/Raspbian

sudo apt-get install bluetooth bluez libbluetooth-dev libudev-dev libusb-1.0-0-dev

Make sure node is on your path, if it's not, some options:

• symlink nodejs to node: sudo ln -s /usr/bin/nodejs /usr/bin/node
• install Node.js using the NodeSource package

Fedora / Other-RPM based

sudo yum install bluez bluez-libs bluez-libs-devel

Intel Edison

See Configure Intel Edison for Bluetooth LE (Smart) Development

FreeBSD

Make sure you have GNU Make:

sudo pkg install gmake

Disable automatic loading of the default Bluetooth stack by putting no-ubt.conf into /usr/local/etc/devd/no-ubt.conf and restarting devd (sudo service devd restart).

Unload ng_ubt kernel module if already loaded:

sudo kldunload ng_ubt

Make sure you have read and write permissions on the /dev/usb/* device that corresponds to your Bluetooth adapter.

Windows

• node-gyp requirements for Windows
  • Python 2.7
  • Visual Studio (Express)
• node-bluetooth-hci-socket prerequisites
  • Compatible Bluetooth 4.0 USB adapter
  • WinUSB driver setup for Bluetooth 4.0 USB adapter, using Zadig tool

API Reference

Actions

Wait for powered on state

// Promise-based
await bleno.waitForPoweredOnAsync(timeout: number); // timeout in milliseconds

Set address

// Callback-based
bleno.setAddress('00:11:22:33:44:55'); // set adapter's mac address

// Promise-based
await bleno.setAddressAsync('00:11:22:33:44:55');

NOTE: Currently this feature is only supported on HCI as it's using vendor specific commands. Source of the commands is based on the BlueZ bdaddr.c. NOTE: bleno.state must be poweredOn before address can be set. bleno.on('stateChange', callback(state)); can be used to listen for state change events.

Advertising

Start advertising

NOTE: bleno.state must be poweredOn before advertising is started. bleno.on('stateChange', callback(state)); can be used register for state change events.

// Callback-based
var name = 'name';
var serviceUuids = ['fffffffffffffffffffffffffffffff0']
bleno.startAdvertising(name, serviceUuids[, callback(error)]);

// Promise-based
await bleno.startAdvertisingAsync(name, serviceUuids);

Note:: there are limits on the name and service UUID's

• name
  • maximum 26 bytes
• service UUID's
  • 1 128-bit service UUID
  • 1 128-bit service UUID + 2 16-bit service UUID's
  • 7 16-bit service UUID

Start advertising iBeacon

// Callback-based
var uuid = 'e2c56db5dffb48d2b060d0f5a71096e0';
var major = 0; // 0x0000 - 0xffff
var minor = 0; // 0x0000 - 0xffff
var measuredPower = -59; // -128 - 127

bleno.startAdvertisingIBeacon(uuid, major, minor, measuredPower[, callback(error)]);

// Promise-based
await bleno.startAdvertisingIBeaconAsync(uuid, major, minor, measuredPower);

Notes::

• OS X:
  • in iBeacon mode your peripheral is non-connectable!

Start advertising with EIR data (Linux only)

// Callback-based
var scanData = Buffer.alloc(...); // maximum 31 bytes
var advertisementData = Buffer.alloc(...); // maximum 31 bytes

bleno.startAdvertisingWithEIRData(advertisementData[, scanData, callback(error)]);

// Promise-based
await bleno.startAdvertisingWithEIRDataAsync(advertisementData[, scanData]);

• For EIR format section Bluetooth Core Specification sections and 8 and 18 for more information the data format.

Stop advertising

// Callback-based
bleno.stopAdvertising([callback]);

// Promise-based
await bleno.stopAdvertisingAsync();

Set services

Set the primary services available on the peripheral.

// Callback-based
var services = [
   ... // see PrimaryService for data type
];

bleno.setServices(services[, callback(error)]);

// Promise-based
await bleno.setServicesAsync(services);

Disconnect client

bleno.disconnect(); // Linux only

Update RSSI

// Callback-based
bleno.updateRssi([callback(error, rssi)]); // not available in OS X 10.9

// Promise-based
const rssi = await bleno.updateRssiAsync();

Primary Service

var PrimaryService = bleno.PrimaryService;

var primaryService = new PrimaryService({
    uuid: 'fffffffffffffffffffffffffffffff0', // or 'fff0' for 16-bit
    characteristics: [
        // see Characteristic for data type
    ]
});

Characteristic

var Characteristic = bleno.Characteristic;

var characteristic = new Characteristic({
    uuid: 'fffffffffffffffffffffffffffffff1', // or 'fff1' for 16-bit
    properties: [ ... ], // can be a combination of 'read', 'write', 'writeWithoutResponse', 'notify', 'indicate'
    secure: [ ... ], // enable security for properties, can be a combination of 'read', 'write', 'writeWithoutResponse', 'notify', 'indicate'
    value: null, // optional static value, must be of type Buffer - for read only characteristics
    descriptors: [
        // see Descriptor for data type
    ],
    onReadRequest: null, // optional read request handler, function(handle, offset, callback) { ... }
    onWriteRequest: null, // optional write request handler, function(handle, data, offset, withoutResponse, callback) { ...}
    onSubscribe: null, // optional notify/indicate subscribe handler, function(handle, maxValueSize, updateValueCallback) { ...}
    onUnsubscribe: null, // optional notify/indicate unsubscribe handler, function(handle) { ...}
    onNotify: null, // optional notify sent handler, function(handle) { ...}
    onIndicate: null // optional indicate confirmation received handler, function(handle) { ...}
});

Multi-Connection Support

With multi-connection support, each handler now receives a handle parameter to identify which client connection is making the request:

// Example of a characteristic with multi-connection support
var multiConnectionCharacteristic = new Characteristic({
    uuid: 'fff1',
    properties: ['read', 'write', 'notify'],
    onReadRequest: function(handle, offset, callback) {
        console.log('Read request from connection: ' + handle);
        // Process the read request for this specific connection
        callback(Characteristic.RESULT_SUCCESS, Buffer.from('Data for connection ' + handle));
    },
    onWriteRequest: function(handle, data, offset, withoutResponse, callback) {
        console.log('Write request from connection: ' + handle);
        // Process the write request for this specific connection
        console.log('Data received: ' + data.toString());
        callback(Characteristic.RESULT_SUCCESS);
    },
    onSubscribe: function(handle, maxValueSize, updateValueCallback) {
        console.log('Subscribe from connection: ' + handle);
        // Store the callback for this specific connection to use later
        // You might want to store these in a Map keyed by handle
        connectionCallbacks.set(handle, updateValueCallback);
    },
    onUnsubscribe: function(handle) {
        console.log('Unsubscribe from connection: ' + handle);
        // Remove the callback for this connection
        connectionCallbacks.delete(handle);
    }
});

// Later, to notify a specific connection:
const callback = connectionCallbacks.get(someConnectionHandle);
if (callback) {
    callback(Buffer.from('Notification for connection ' + someConnectionHandle));
}

Result codes

• Characteristic.RESULT_SUCCESS
• Characteristic.RESULT_INVALID_OFFSET
• Characteristic.RESULT_INVALID_ATTRIBUTE_LENGTH
• Characteristic.RESULT_UNLIKELY_ERROR
• Characteristic.RESULT_ATTR_NOT_LONG

Read requests

Can specify read request handler via constructor options or by extending Characteristic and overriding onReadRequest.

Parameters to handler are

• handle (connection handle)
• offset (0x0000 - 0xffff)
• callback

callback must be called with result and data (of type Buffer) - can be async.

var result = Characteristic.RESULT_SUCCESS;
var data = Buffer.alloc( ... );

callback(result, data);

Write requests

Can specify write request handler via constructor options or by extending Characteristic and overriding onWriteRequest.

Parameters to handler are

• handle (connection handle)
• data (Buffer)
• offset (0x0000 - 0xffff)
• withoutResponse (true | false)
• callback.

callback must be called with result code - can be async.

var result = Characteristic.RESULT_SUCCESS;

callback(result);

Notify subscribe

Can specify notify subscribe handler via constructor options or by extending Characteristic and overriding onSubscribe.

Parameters to handler are

• handle (connection handle)
• maxValueSize (maximum data size)
• updateValueCallback (callback to call when value has changed)

Notify unsubscribe

Can specify notify unsubscribe handler via constructor options or by extending Characteristic and overriding onUnsubscribe.

Parameters to handler are

• handle (connection handle)

Notify value changes

Call the updateValueCallback callback (see Notify subscribe), with an argument of type Buffer

Can specify notify sent handler via constructor options or by extending Characteristic and overriding onNotify.

Parameters to handler are

• handle (connection handle)

Descriptor

var Descriptor = bleno.Descriptor;

var descriptor = new Descriptor({
    uuid: '2901',
    value: 'value' // static value, must be of type Buffer or string if set
});

Events

Adapter state change

state = <"unknown" | "resetting" | "unsupported" | "unauthorized" | "poweredOff" | "poweredOn">

bleno.on('stateChange', callback(state));

Platform

bleno.on('platform', callback(platform));

Address change

bleno.on('addressChange', callback(address));

MTU change

bleno.on('mtuChange', callback(mtu));

Advertisement started

bleno.on('advertisingStart', callback(error));

bleno.on('advertisingStartError', callback(error));

Advertisement stopped

bleno.on('advertisingStop', callback);

Services set

bleno.on('servicesSet', callback(error));

bleno.on('servicesSetError', callback(error));

Accept

bleno.on('accept', callback(address, handle)); // handle provided for multi-connection support

Disconnect

bleno.on('disconnect', callback(address, handle)); // handle provided for multi-connection support

RSSI Update

bleno.on('rssiUpdate', callback(rssi));

Running on Linux

Note: Make sure you've also checked the Linux Prerequisites

Running without root/sudo

Run the following command:

sudo setcap cap_net_raw+eip $(eval readlink -f `which node`)

This grants the node binary cap_net_raw privileges, so it can start/stop BLE advertising.

Note: The above command requires setcap to be installed, it can be installed using the following:

• apt: sudo apt-get install libcap2-bin
• yum: su -c \'yum install libcap2-bin\'

Multiple Adapters

hci0 is used by default to override set the BLENO_HCI_DEVICE_ID environment variable to the interface number.

Example, specify hci1:

sudo BLENO_HCI_DEVICE_ID=1 node <your file>.js

Set custom device name

By default bleno uses the hostname (require('os').hostname()) as the value for the device name (0x2a00) characterisic, to match the behaviour of OS X.

A custom device name can be specified by setting the BLENO_DEVICE_NAME environment variable:

sudo BLENO_DEVICE_NAME="custom device name" node <your file>.js

or

process.env['BLENO_DEVICE_NAME'] = 'custom device name';

Set Advertising Interval

bleno uses a 100 ms advertising interval by default.

A custom advertising interval can be specified by setting the BLENO_ADVERTISING_INTERVAL environment variable with the desired value in milliseconds:

sudo BLENO_ADVERTISING_INTERVAL=500 node <your file>.js

Advertising intervals must be between 20 ms to 10 s (10,000 ms).

Useful tools/links

• Tools
  • LightBlue for iOS/OS X
  • nRF Master Control Panel (BLE) for Android
  • hcitool and gatttool by BlueZ for Linux