Cannot get notifications from HCI service #62
Description
Hi out there,
I got an issue I cannot solve by myself so some help would be appreciated. Here my configuration.
I am on a Raspberry with Raspbian. I have a Microsoft Surface Dial (which is a HCI device). The Surface Dial is paired with the Raspberry. I did this with bluetoothctl.
I like to get notifications directly from D-Bus so I disabled the HCI service in /lib/systemd/system/bluetooth.service by setting ExecStart=/usr/libexec/bluetooth/bluetoothd --noplugin=sap,input,hog to be able to access the HCI service via D-Bus.
In my first implementation I used RAW HCI to get the data but after a disconnect of the device it takes more than three seconds after touching the Surface Dial until the HCI-Service was available again. This is much to long as rotating the dial a sudden reaction must occur. This is why I tried to use D-Bus. So in this implementation here I get the connect event immediately but I was not able to get the data any more 👎
I used the code below to get notification from the HCI Report Characteristic of the Surface Dial but it failed:
var deviceUuid = '70:BC:10:87:C1:B8';
var genericServiceUuid = '1812';
var genericCharacteristicUuid = '2a4d';
async function startBleServer() {
console.log('************************************** Start BLE-Server: ' + deviceUuid);
var { createBluetooth } = require('node-ble');
var { bluetooth, destroy } = createBluetooth();
var adapter = await bluetooth.defaultAdapter();
console.log('adapter: ');
// discover surfache Dial
if (! await adapter.isDiscovering()) {
console.log('Start discovery: ');
await adapter.startDiscovery()
}
console.log('Wait for device: ' + deviceUuid);
var device = await adapter.waitDevice(deviceUuid);
device.on('disconnect', function () {
console.log('######## Ble >>>>> EVENT: ' + 'Device disconnected');
})
device.on('connect', function () {
console.log('######## Ble >>>>> EVENT: ' + 'Device connected');
})
console.log('stop discovery');
await adapter.stopDiscovery()
console.log('discovered, wait till connected');
await device.connect()
console.log('connected, wait for GATT server');
var gattServer = await device.gatt();
console.log('gatt server ready!');
// Get service UUIDs and search for service 1812
var myServices = await gattServer.services();
var hciServiceUuid = null;
for (var i = 0; i < myServices.length; i++) {
if (myServices[i].indexOf(genericServiceUuid + '-') >= 0) hciServiceUuid = myServices[i];
}
console.log('HCI service UUID: ' + hciServiceUuid);
// If I found the UUID of the HCI-Service get the HCI service
if (hciServiceUuid) {
//********************* get hciService
var hciService = await gattServer.getPrimaryService(hciServiceUuid);
console.log('Serice ' + hciServiceUuid + ' discovered');
// get the characteristic UUIDs
var myCharacteristics = await hciService.characteristics();
console.log('Got HCI characteristic UUIDs');
// find Reprt Characteristi UUIDs suchen
var reportCharacteristicUuid = null;
for (var i = 0; i < myCharacteristics.length; i++) {
if (myCharacteristics[i].indexOf(genericCharacteristicUuid + '-') >= 0) reportCharacteristicUuid = myCharacteristics[i];
}
console.log('HCI Characteristic UUID' + reportCharacteristicUuid);
// get Report Characteristic
var reportCharacteristic = await hciService.getCharacteristic(reportCharacteristicUuid);
console.log('Report Characteristics ' + reportCharacteristicUuid + ' found');
// Setup callback for Notifications
reportCharacteristic.on('valuechanged', buffer => {
console.log('Data received');
console.log(buffer)
})
console.log('callback set');
await reportCharacteristic.startNotifications();
console.log('Notification started');
}
}
startBleServer();
Running this code anything worked fine at the beginning. The service and the characteristic were found. But trying to setup the notification I get an error message. See output below:
root@DrCWO:/home/pi# node xx_ble.js
************************************** Start BLE-Server: 70:BC:10:87:C1:B8
adapter:
Start discovery:
Wait for device: 70:BC:10:87:C1:B8
stop discovery
discovered, wait till connected
######## Ble >>>>> EVENT: Device connected
connected, wait for GATT server
gatt server ready!
HCI service UUID: 00001812-0000-1000-8000-00805f9b34fb
Serice 00001812-0000-1000-8000-00805f9b34fb discovered
Got HCI characteristic UUIDs
HCI Characteristic UUID00002a4d-0000-1000-8000-00805f9b34fb
Report Characteristics 00002a4d-0000-1000-8000-00805f9b34fb found
callback set
/home/pi/rooExtend/node_modules/dbus-next/lib/bus.js:343
return reject(new DBusError(reply.errorName, reply.body[0], reply));
^
DBusError: Operation is not supported
at _methodReturnHandlers.<computed> (/home/pi/rooExtend/node_modules/dbus-next/lib/bus.js:343:27)
at handleMessage (/home/pi/rooExtend/node_modules/dbus-next/lib/bus.js:101:11)
at EventEmitter.<anonymous> (/home/pi/rooExtend/node_modules/dbus-next/lib/bus.js:151:9)
at EventEmitter.emit (node:events:513:28)
at /home/pi/rooExtend/node_modules/dbus-next/lib/connection.js:132:14
at USocket.<anonymous> (/home/pi/rooExtend/node_modules/dbus-next/lib/message.js:65:9)
at USocket.emit (node:events:513:28)
at emitReadable_ (node:internal/streams/readable:590:12)
at process.processTicksAndRejections (node:internal/process/task_queues:81:21) {
type: 'org.bluez.Error.NotSupported',
text: 'Operation is not supported',
reply: Message {
type: 3,
_sent: false,
_serial: 3374,
path: undefined,
interface: undefined,
member: undefined,
errorName: 'org.bluez.Error.NotSupported',
replySerial: 100,
destination: ':1.3859',
sender: ':1.3820',
signature: 's',
body: [ 'Operation is not supported' ],
flags: 1
}
}
Node.js v18.7.0
Any idea why I cannot start the notification?
Best DrCWO