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This plugin enables communication between a phone and Bluetooth Low Energy (BLE) peripherals.

The plugin provides a simple JavaScript API for iOS and Android.

• Scan for peripherals
• Connect to a peripheral
• Read the value of a characteristic
• Write new value to a characteristic
• Get notified when characteristic's value changes

Advertising information is returned when scanning for peripherals. Service, characteristic, and property info is returned when connecting to a peripheral. All access is via service and characteristic UUIDs. The plugin manages handles internally.

Simultaneous connections to multiple peripherals are supported.

Repo: https://github.com/don/cordova-plugin-ble-central

Installation

1. Install the Cordova and Ionic Native plugins:
   

   $ ionic cordova plugin add cordova-plugin-ble-central
   $ npm install --save @ionic-native/ble@4
   

2. Add this plugin to your app's module

Supported platforms

• Android
• iOS

Usage

import { BLE } from '@ionic-native/ble';

constructor(private ble: BLE) { }

Peripheral Data

Peripheral Data is passed to the success callback when scanning and connecting. Limited data is passed when scanning.

{
    'name': 'Battery Demo',
    'id': '20:FF:D0:FF:D1:C0',
    'advertising': [2,1,6,3,3,15,24,8,9,66,97,116,116,101,114,121],
    'rssi': -55
}

After connecting, the peripheral object also includes service, characteristic and descriptor information.

{
    'name': 'Battery Demo',
    'id': '20:FF:D0:FF:D1:C0',
    'advertising': [2,1,6,3,3,15,24,8,9,66,97,116,116,101,114,121],
    'rssi': -55,
    'services': [
        '1800',
        '1801',
        '180f'
    ],
    'characteristics': [
        {
            'service': '1800',
            'characteristic': '2a00',
            'properties': [
                'Read'
            ]
        },
        {
            'service': '1800',
            'characteristic': '2a01',
            'properties': [
                'Read'
            ]
        },
        {
            'service': '1801',
            'characteristic': '2a05',
            'properties': [
                'Read'
            ]
        },
        {
            'service': '180f',
            'characteristic': '2a19',
            'properties': [
                'Read'
            ],
            'descriptors': [
                {
                    'uuid': '2901'
                },
                {
                    'uuid': '2904'
                }
            ]
        }
    ]
}

Advertising Data

Bluetooth advertising data is returned in when scanning for devices. The format varies depending on your platform. On Android advertising data will be the raw advertising bytes. iOS does not allow access to raw advertising data, so a dictionary of data is returned.

The advertising information for both Android and iOS appears to be a combination of advertising data and scan response data.

Android

 {
     'name': 'demo',
     'id': '00:1A:7D:DA:71:13',
     'advertising': ArrayBuffer,
    'rssi': -37
}

Convert the advertising info to a Uint8Array for processing. var adData = new Uint8Array(peripheral.advertising)

iOS

Note that iOS uses the string value of the constants for the Advertisement Data Retrieval Keys. This will likely change in the future.

{
    'name': 'demo',
    'id': 'D8479A4F-7517-BCD3-91B5-3302B2F81802',
    'advertising': {
        'kCBAdvDataChannel': 37,
        'kCBAdvDataServiceData': {
            'FED8': {
                'byteLength': 7 // data not shown
            }
        },
        'kCBAdvDataLocalName': 'demo',
        'kCBAdvDataServiceUUIDs': ['FED8'],
        'kCBAdvDataManufacturerData': {
            'byteLength': 7  // data not shown
        },
        'kCBAdvDataTxPowerLevel': 32,
        'kCBAdvDataIsConnectable': true
    },
    'rssi': -53
}

Typed Arrays

This plugin uses typed Arrays or ArrayBuffers for sending and receiving data.

This means that you need convert your data to ArrayBuffers before sending and from ArrayBuffers when receiving.

// ASCII only
function stringToBytes(string) {
   var array = new Uint8Array(string.length);
   for (var i = 0, l = string.length; i < l; i++) {
       array[i] = string.charCodeAt(i);
    }
    return array.buffer;
}

// ASCII only
function bytesToString(buffer) {
    return String.fromCharCode.apply(null, new Uint8Array(buffer));
}

You can read more about typed arrays in these articles on MDN and HTML5 Rocks.

UUIDs

UUIDs are always strings and not numbers. Some 16-bit UUIDs, such as '2220' look like integers, but they're not. (The integer 2220 is 0x8AC in hex.) This isn't a problem with 128 bit UUIDs since they look like strings 82b9e6e1-593a-456f-be9b-9215160ebcac. All 16-bit UUIDs should also be passed to methods as strings.

Instance Members

scan(services, seconds)

Scan and discover BLE peripherals for the specified amount of time.

startScan(services)

Scan and discover BLE peripherals until stopScan is called.

startScanWithOptions(services, options)

Scans for BLE devices. This function operates similarly to the startScan function, but allows you to specify extra options (like allowing duplicate device reports).

stopScan()

Stop a scan started by startScan.

connect(deviceId)

Connect to a peripheral.

autoConnect(deviceId, connectCallback, disconnectCallback)

Establish an automatic connection to a peripheral. The phone will automatically connect to the Bluetooth peripheral whenever it is in range. The autoConnect function uses callbacks instead of observables because connect and disconnect can each be called many times as a devices connects and disconnects.

On Android you can pass a MAC address directly to autoConnect. With iOS, you need to get a device id by scanning, calling ble.peripheralsWithIdentifiers, or calling ble.connectedPeripheralsWithServices.

requestMtu(deviceId, mtuSize)

Request MTU size. May be used to fix the Error 14 “Unlikely” on write requests with more than 20 bytes.

refreshDeviceCache(deviceId, timeoutMillis)

Refresh Device Cache This method may fix a issue of old cached services and characteristics. NOTE Since this uses an undocumented API it’s not guaranteed to work. If you choose a too low delay time (timeoutMillis) the method could fail.

disconnect(deviceId)

Disconnect from a peripheral.

read(deviceId, serviceUUID, characteristicUUID)

Read the value of a characteristic.

write(deviceId, serviceUUID, characteristicUUID, value)

Write the value of a characteristic.

writeWithoutResponse(deviceId, serviceUUID, characteristicUUID, value)

Write the value of a characteristic without waiting for confirmation from the peripheral.

startNotification(deviceId, serviceUUID, characteristicUUID)

Register to be notified when the value of a characteristic changes.

stopNotification(deviceId, serviceUUID, characteristicUUID)

Stop being notified when the value of a characteristic changes.

isConnected(deviceId)

Report the connection status.

isEnabled()

Report if bluetooth is enabled.

startStateNotifications()

Register to be notified when Bluetooth state changes on the device.

stopStateNotifications()

Stop state notifications.

showBluetoothSettings()

Open System Bluetooth settings (Android only).

enable()

Enable Bluetooth on the device (Android only).

readRSSI(deviceId)

Read the RSSI value on the device connection.

connectedPeripheralsWithServices(services)

Retrieves a list of the peripherals (containing any of the specified services) currently connected to the system. The peripheral list is sent to the success callback. iOS only

peripheralsWithIdentifiers(uuids)

Find the connected peripherals offering the listed service UUIDs. iOS only

bondedDevices()

Find the bonded devices Android only

BLEScanOptions