cordova-plugin-ble-central
Advanced tools
This plugin enables communication between a phone and Bluetooth Low Energy (BLE) peripherals.
The plugin provides a simple JavaScript API for iOS and Android.
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.
This plugin isn't intended for scanning beacons. Try cordova-plugin-ibeacon for iBeacons.
If you want to create Bluetooth devices, try cordova-plugin-ble-peripheral.
See the examples for ideas on how this plugin can be used.
$ cordova plugin add cordova-plugin-ble-central
$ phonegap plugin add cordova-plugin-ble-central
Edit config.xml to install the plugin for PhoneGap Build.
<gap:plugin name="cordova-plugin-ble-central" source="npm" />
<preference name="phonegap-version" value="cli-6.1.0" />
This plugin is included in iOS and Android versions of the PhoneGap Developer App.
Note that this plugin's id changed from com.megster.cordova.ble to cordova-plugin-ble-central as part of the migration from the Cordova plugin repo to npm.
For iOS, apps will crash unless they include usage description keys for the types of data they access. Applications targeting iOS 13 and later, define NSBluetoothAlwaysUsageDescription to tell the user why the application needs Bluetooth. For apps with a deployment target earlier than iOS 13, add NSBluetoothPeripheralUsageDescription. Both of these keys can be set when installing the plugin by passing the BLUETOOTH_USAGE_DESCRIPTION variable.
$ cordova plugin add cordova-plugin-ble-central --variable BLUETOOTH_USAGE_DESCRIPTION="Your description here"
See Apple's documentation about Protected Resources for more details. If your app needs other permissions like location, try the cordova-custom-config plugin.
Scan and discover BLE peripherals.
ble.scan(services, seconds, success, failure);
Function scan scans for BLE devices. The success callback is called each time a peripheral is discovered. Scanning automatically stops after the specified number of seconds.
{
"name": "TI SensorTag",
"id": "BD922605-1B07-4D55-8D09-B66653E51BBA",
"rssi": -79,
"advertising": /* ArrayBuffer or map */
}
Advertising information format varies depending on your platform. See Advertising Data for more information.
With Android SDK >= 23 (6.0), additional permissions are required for Bluetooth low energy scanning. The location permission ACCESS_COARSE_LOCATION is required because Bluetooth beacons can be used to determine a user's location. If necessary, the plugin will prompt the user to allow the app to access to device's location. If the user denies permission, the scan failure callback will receive the error "Location permission not granted".
Location Services must be enabled for Bluetooth scanning. If location services are disabled, the failure callback will receive the error "Location services are disabled". If you want to manage location permission and screens, try the cordova-diagonostic-plugin or the Ionic Native Diagnostic plugin.
ble.scan([], 5, function(device) {
console.log(JSON.stringify(device));
}, failure);
Scan and discover BLE peripherals.
ble.startScan(services, success, failure);
Function startScan scans for BLE devices. The success callback is called each time a peripheral is discovered. Scanning will continue until stopScan is called.
{
"name": "TI SensorTag",
"id": "BD922605-1B07-4D55-8D09-B66653E51BBA",
"rssi": -79,
"advertising": /* ArrayBuffer or map */
}
Advertising information format varies depending on your platform. See Advertising Data for more information.
See the location permission notes above for information about Location Services in Android SDK >= 23.
ble.startScan([], function(device) {
console.log(JSON.stringify(device));
}, failure);
setTimeout(ble.stopScan,
5000,
function() { console.log("Scan complete"); },
function() { console.log("stopScan failed"); }
);
Scan and discover BLE peripherals, specifying scan options.
ble.startScanWithOptions(services, options, success, failure);
Function startScanWithOptions scans for BLE devices. It operates similarly to the startScan function, but allows you to specify extra options (like allowing duplicate device reports). The success callback is called each time a peripheral is discovered. Scanning will continue until stopScan is called.
{
"name": "TI SensorTag",
"id": "BD922605-1B07-4D55-8D09-B66653E51BBA",
"rssi": -79,
"advertising": /* ArrayBuffer or map */
}
Advertising information format varies depending on your platform. See Advertising Data for more information.
See the location permission notes above for information about Location Services in Android SDK >= 23.
ble.startScanWithOptions([],
{ reportDuplicates: true }
function(device) {
console.log(JSON.stringify(device));
},
failure);
setTimeout(ble.stopScan,
5000,
function() { console.log("Scan complete"); },
function() { console.log("stopScan failed"); }
);
Stop scanning for BLE peripherals.
ble.stopScan(success, failure);
Function stopScan stops scanning for BLE devices.
ble.startScan([], function(device) {
console.log(JSON.stringify(device));
}, failure);
setTimeout(ble.stopScan,
5000,
function() { console.log("Scan complete"); },
function() { console.log("stopScan failed"); }
);
/* Alternate syntax
setTimeout(function() {
ble.stopScan(
function() { console.log("Scan complete"); },
function() { console.log("stopScan failed"); }
);
}, 5000);
*/
Connect to a peripheral.
ble.connect(device_id, connectCallback, disconnectCallback);
Function connect connects to a BLE peripheral. The callback is long running. The connect callback will be called when the connection is successful. Service and characteristic info will be passed to the connect callback in the peripheral object.
The disconnect callback is called if the connection fails, or later if the peripheral disconnects. When possible, a peripheral object is passed to the failure callback. The disconnect callback is only called when the peripheral initates the disconnection. The disconnect callback is not called when the application calls ble.disconnect. The disconnect callback is how your app knows the peripheral inintiated a disconnect.
Android can connect to peripherals using MAC address without scanning. If the MAC address is not found the connection will time out.
For iOS, the plugin needs to know about any device UUID before calling connect. You can do this by calling ble.scan, ble.startScan, ble.connectedPeripheralsWithServices, or ble.peripheralsWithIdentifiers so the plugin has a list of available peripherals.
Establish an automatic connection to a peripheral.
ble.autoConnect(device_id, connectCallback, disconnectCallback);
Automatically connect to a device when it is in range of the phone. When the device connects, the connect callback is called with a peripheral object. The call to autoConnect will not time out. It will wait forever until the device is in range. When the peripheral disconnects, the disconnect callback is called with a peripheral object.
Calling ble.disconnect will stop the automatic reconnection.
Both the connect and disconnect callbacks can be called many times as the device connects and disconnects. Do not wrap this function in a Promise or Observable.
On iOS, background notifications on ios must be enabled if you want to run in the background. On Android, this relies on the autoConnect argument of BluetoothDevice.connectGatt(). Not all Android devices implement this feature correctly.
See notes about scanning before connecting
Disconnect.
ble.disconnect(device_id, [success], [failure]);
Function disconnect disconnects the selected device.
requestMtu
ble.requestMtu(device_id, mtu, [success], [failure]);
When performing a write request operation (write without response), the data sent is truncated to the MTU size. This function may be used to request (on Android) a larger MTU size to be able to send more data at once.
refreshDeviceCache
ble.refreshDeviceCache(deviceId, timeoutMillis, [success], [failure]);
Some poorly behaved devices show old cached services and characteristics info. (Usually because they don't implement Service Changed 0x2a05 on Generic Attribute Service 0x1801 and the central doesn't know the data needs to be refreshed.) This method might help.
NOTE Since this uses an undocumented API it's not guaranteed to work.
Reads the value of a characteristic.
ble.read(device_id, service_uuid, characteristic_uuid, success, failure);
Function read reads the value of the characteristic.
Raw data is passed from native code to the callback as an ArrayBuffer.
Retrieves an ArrayBuffer when reading data.
// read data from a characteristic, do something with output data
ble.read(device_id, service_uuid, characteristic_uuid,
function(data){
console.log("Hooray we have data"+JSON.stringify(data));
alert("Successfully read data from device."+JSON.stringify(data));
},
function(failure){
alert("Failed to read characteristic from device.");
}
);
Writes data to a characteristic.
ble.write(device_id, service_uuid, characteristic_uuid, data, success, failure);
Function write writes data to a characteristic.
Use an ArrayBuffer when writing data.
// send 1 byte to switch a light on
var data = new Uint8Array(1);
data[0] = 1;
ble.write(device_id, "FF10", "FF11", data.buffer, success, failure);
// send a 3 byte value with RGB color
var data = new Uint8Array(3);
data[0] = 0xFF; // red
data[1] = 0x00; // green
data[2] = 0xFF; // blue
ble.write(device_id, "ccc0", "ccc1", data.buffer, success, failure);
// send a 32 bit integer
var data = new Uint32Array(1);
data[0] = counterInput.value;
ble.write(device_id, SERVICE, CHARACTERISTIC, data.buffer, success, failure);
Writes data to a characteristic without confirmation from the peripheral.
ble.writeWithoutResponse(device_id, service_uuid, characteristic_uuid, data, success, failure);
Function writeWithoutResponse writes data to a characteristic without a response from the peripheral. You are not notified if the write fails in the BLE stack. The success callback is be called when the characteristic is written.
Register to be notified when the value of a characteristic changes.
ble.startNotification(device_id, service_uuid, characteristic_uuid, success, failure);
Function startNotification registers a callback that is called every time the value of a characteristic changes. This method handles both notifications and indications. The success callback is called multiple times.
Raw data is passed from native code to the success callback as an ArrayBuffer.
See Background Notifications on iOS
var onData = function(buffer) {
// Decode the ArrayBuffer into a typed Array based on the data you expect
var data = new Uint8Array(buffer);
alert("Button state changed to " + data[0]);
}
ble.startNotification(device_id, "FFE0", "FFE1", onData, failure);
Stop being notified when the value of a characteristic changes.
ble.stopNotification(device_id, service_uuid, characteristic_uuid, success, failure);
Function stopNotification stops a previously registered notification callback.
Reports the connection status.
ble.isConnected(device_id, success, failure);
Function isConnected calls the success callback when the peripheral is connected and the failure callback when not connected.
NOTE that for many apps isConnected is unncessary. The app can track the connected state. Ater calling connect the app is connected when the success callback function is called. If the device disconnects at any point in the future, the failure callback of connect will be called.
ble.isConnected(
'FFCA0B09-CB1D-4DC0-A1EF-31AFD3EDFB53',
function() {
console.log("Peripheral is connected");
},
function() {
console.log("Peripheral is *not* connected");
}
);
Reports if bluetooth is enabled.
ble.isEnabled(success, failure);
Function isEnabled calls the success callback when Bluetooth is enabled and the failure callback when Bluetooth is not enabled.
ble.isEnabled(
function() {
console.log("Bluetooth is enabled");
},
function() {
console.log("Bluetooth is *not* enabled");
}
);
Registers to be notified when Bluetooth state changes on the device.
ble.startStateNotifications(success, failure);
Function startStateNotifications calls the success callback when the Bluetooth is enabled or disabled on the device.
States
ble.startStateNotifications(
function(state) {
console.log("Bluetooth is " + state);
}
);
Stops state notifications.
ble.stopStateNotifications(success, failure);
Function stopStateNotifications calls the success callback when Bluetooth state notifications have been stopped.
Show the Bluetooth settings on the device.
ble.showBluetoothSettings(success, failure);
Function showBluetoothSettings opens the Bluetooth settings for the operating systems.
showBluetoothSettings is not available on iOS. Plugins like cordova-diagonostic-plugin and the Ionic Native Diagnostic plugin have APIs to open Bluetooth and other settings, but will often get apps rejected by Apple.
ble.showBluetoothSettings();
Enable Bluetooth on the device.
ble.enable(success, failure);
Function enable prompts the user to enable Bluetooth.
enable is only supported on Android and does not work on iOS.
If enable is called when Bluetooth is already enabled, the user will not prompted and the success callback will be invoked.
ble.enable(
function() {
console.log("Bluetooth is enabled");
},
function() {
console.log("The user did *not* enable Bluetooth");
}
);
Read the RSSI value on the device connection.
ble.readRSSI(device_id, success, failure);
Samples the RSSI value (a measure of signal strength) on the connection to a bluetooth device. Requires that you have established a connection before invoking (otherwise an error will be raised).
var rssiSample;
ble.connect(device_id,
function(device) {
rssiSample = setInterval(function() {
ble.readRSSI(device_id, function(rssi) {
console.log('read RSSI',rssi,'with device', device_id);
}, function(err) {
console.error('unable to read RSSI',err);
clearInterval(rssiSample);
})
}, 5000);
},
function(err) { console.error('error connecting to device')}
);
Find the connected peripherals offering the listed service UUIDs.
ble.connectedPeripheralsWithServices([service], success, failure);
Retreives 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. This function wraps CBCentralManager.retrieveConnectedPeripheralsWithServices:
Find the connected peripherals offering the listed service UUIDs.
ble.peripheralsWithIdentifiers([uuids], success, failure);
Sends a list of known peripherals by their identifiers to the success callback. This function wraps CBCentralManager.retrievePeripheralsWithIdentifiers:
Find the bonded devices.
ble.bondedDevices(success, failure);
Sends a list of bonded low energy peripherals to the success callback.
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"
}
]
}
]
}
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.
Ideally a common format (map or array) would be returned for both platforms in future versions. If you have ideas, please contact me.
{
"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). You application is responsible for parsing all the information out of the advertising ArrayBuffer using the GAP type constants. For example to get the service data from the advertising info, I parse the advertising info into a map and then get the service data to retrieve a characteristic value that is being broadcast.
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": "15B4F1C5-C9C0-4441-BD9F-1A7ED8F7A365",
"advertising": {
"kCBAdvDataLocalName": "demo",
"kCBAdvDataManufacturerData": {}, // arraybuffer data not shown
"kCBAdvDataServiceUUIDs": [
"721b"
],
"kCBAdvDataIsConnectable": true,
"kCBAdvDataServiceData": {
"BBB0": {} // arraybuffer data not shown
},
},
"rssi": -61
}
Some of the values such as kCBAdvDataManufacturerData are ArrayBuffers. The data won't print out, but you can convert it to bytes using new Uint8Array(peripheral.advertisting.kCBAdvDataManufacturerData). Your application is responsible for parsing and decoding any binary data such as kCBAdvDataManufacturerData or kCBAdvDataServiceData.
function onDiscoverDevice(device) {
// log the device as JSON
console.log('Found Device', JSON.stringify(device, null, 2));
// on iOS, print the manufacturer data if it exists
if (device.advertising && device.advertising.kCBAdvDataManufacturerData) {
const mfgData = new Uint8Array(device.advertising.kCBAdvDataManufacturerData);
console.log('Manufacturer Data is', mfgData);
}
}
ble.scan([], 5, onDiscoverDevice, onError);
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 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.
Android applications will continue to receive notification while the application is in the background.
iOS applications need additional configuration to allow Bluetooth to run in the background.
Install the cordova-custom-config plugin.
cordova plugin add cordova-custom-config
Add a new section to config.xml
<platform name="ios">
<config-file parent="UIBackgroundModes" target="*-Info.plist">
<array>
<string>bluetooth-central</string>
</array>
</config-file>
</platform>
See ble-background example project for more details.
Tests require the Cordova Plugin Test Framework
Create a new project
git clone https://github.com/don/cordova-plugin-ble-central
cordova create ble-test com.example.ble.test BLETest
cd ble-test
cordova platform add android
cordova plugin add ../cordova-plugin-ble-central
cordova plugin add ../cordova-plugin-ble-central/tests
cordova plugin add cordova-plugin-test-framework
Change the start page in config.xml
<content src="cdvtests/index.html" />
Run the app on your phone
cordova run android --device
If you need Nordic DFU capability, Tomáš Bedřich has a fork of this plugin that adds an updateFirmware() method that allows users to upgrade nRF5x based chips over the air. https://github.com/fxe-gear/cordova-plugin-ble-central
Apache 2.0
Try the code. If you find an problem or missing feature, file an issue or create a pull request.
FAQs
Bluetooth Low Energy (BLE) Central Plugin
We found that cordova-plugin-ble-central demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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