Bluetooth-Le plugin: No listeners found for event notification

Capacitor
1

Hi,

I am new to Ionic/Capacitor. We are trying to build an App to listen to our sensor’s BLE message through BLE notification/indication.

We decide to use the capacitor plugin GitHub - capacitor-community/bluetooth-le: Capacitor plugin for Bluetooth Low Energy instead of the old codorvar.
I managed to connect the sensor through BLE, and enable the notification from the sensor.
However, the ionic side gives an error message as long as the sensor sends notification/indication to the phone.

Here are the logs from android studio.

2021-08-04 17:49:11.527 11398-11574/io.ionic.starter V/Capacitor: callback: 61954489, pluginId: BluetoothLe, methodName: connect, methodData: {"deviceId":"E8:EB:1B:53:D0:99"}
2021-08-04 17:49:11.533 11398-11499/io.ionic.starter D/BluetoothGatt: connect() - device: E8:EB:1B:53:D0:99, auto: false
2021-08-04 17:49:11.533 11398-11499/io.ionic.starter D/BluetoothGatt: registerApp()
2021-08-04 17:49:11.533 11398-11499/io.ionic.starter D/BluetoothGatt: registerApp() - UUID=e3baf6e5-065b-4422-bcad-2fbe89faf14b
2021-08-04 17:49:11.540 11398-11415/io.ionic.starter D/BluetoothGatt: onClientRegistered() - status=0 clientIf=5
2021-08-04 17:49:11.697 11398-11415/io.ionic.starter D/BluetoothGatt: onClientConnectionState() - status=0 clientIf=5 device=E8:EB:1B:53:D0:99
2021-08-04 17:49:11.698 11398-11415/io.ionic.starter D/Device: Connected to GATT server. Starting service discovery.
2021-08-04 17:49:11.698 11398-11415/io.ionic.starter D/BluetoothGatt: discoverServices() - device: E8:EB:1B:53:D0:99
2021-08-04 17:49:12.175 11398-11415/io.ionic.starter D/BluetoothGatt: onConnectionUpdated() - Device=E8:EB:1B:53:D0:99 interval=6 latency=0 timeout=500 status=0
2021-08-04 17:49:12.516 11398-11415/io.ionic.starter D/BluetoothGatt: onSearchComplete() = Device=E8:EB:1B:53:D0:99 Status=0
2021-08-04 17:49:12.516 11398-11415/io.ionic.starter D/Device: requestMtu 512
2021-08-04 17:49:12.516 11398-11415/io.ionic.starter D/BluetoothGatt: configureMTU() - device: E8:EB:1B:53:D0:99 mtu: 512
2021-08-04 17:49:12.534 11398-11415/io.ionic.starter D/BluetoothGatt: onConfigureMTU() - Device=E8:EB:1B:53:D0:99 mtu=158 status=0
2021-08-04 17:49:12.534 11398-11415/io.ionic.starter D/Device: MTU changed: 158
2021-08-04 17:49:12.534 11398-11415/io.ionic.starter D/Device: resolve: connect Connected.
2021-08-04 17:49:12.539 11398-11398/io.ionic.starter I/Capacitor/Console: File: http://localhost/ - Line 213 - Msg: undefined
2021-08-04 17:49:12.540 11398-11398/io.ionic.starter I/Capacitor/Console: File: http://localhost/js/chunk-69312c9a.ae92b072.js - Line 3 - Msg: connected to device [object Object]
2021-08-04 17:49:12.540 11398-11574/io.ionic.starter V/Capacitor/Plugin: To native (Capacitor plugin): callbackId: 61954490, pluginId: BluetoothLe, methodName: addListener
2021-08-04 17:49:12.541 11398-11574/io.ionic.starter V/Capacitor: callback: 61954490, pluginId: BluetoothLe, methodName: addListener, methodData: {"eventName":"notification|E8:EB:1B:53:D0:99|49535343-FE7D-4AE5-8FA9-9FAFD205E455|49535343-1E4D-4BD9-BA61-23C647249616"}
2021-08-04 17:49:12.544 11398-11574/io.ionic.starter V/Capacitor/Plugin: To native (Capacitor plugin): callbackId: 61954491, pluginId: BluetoothLe, methodName: startNotifications
2021-08-04 17:49:12.544 11398-11574/io.ionic.starter V/Capacitor: callback: 61954491, pluginId: BluetoothLe, methodName: startNotifications, methodData: {"deviceId":"E8:EB:1B:53:D0:99","service":"49535343-FE7D-4AE5-8FA9-9FAFD205E455","characteristic":"49535343-1E4D-4BD9-BA61-23C647249616"}
2021-08-04 17:49:12.546 11398-11499/io.ionic.starter D/BluetoothGatt: setCharacteristicNotification() - uuid: 49535343-1e4d-4bd9-ba61-23c647249616 enable: true
2021-08-04 17:49:12.565 11398-11415/io.ionic.starter D/Device: resolve: setNotifications|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616 Setting notification succeeded.
2021-08-04 17:49:12.568 11398-11398/io.ionic.starter I/Capacitor/Console: File: http://localhost/ - Line 213 - Msg: undefined
2021-08-04 17:49:12.589 11398-11415/io.ionic.starter V/Capacitor/BluetoothLe: Notifying listeners for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:12.589 11398-11415/io.ionic.starter D/Capacitor/BluetoothLe: No listeners found for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:12.628 11398-11415/io.ionic.starter D/BluetoothGatt: onConnectionUpdated() - Device=E8:EB:1B:53:D0:99 interval=36 latency=0 timeout=500 status=0
2021-08-04 17:49:13.074 11398-11415/io.ionic.starter D/BluetoothGatt: onConnectionUpdated() - Device=E8:EB:1B:53:D0:99 interval=24 latency=0 timeout=512 status=0
2021-08-04 17:49:13.620 11398-11415/io.ionic.starter V/Capacitor/BluetoothLe: Notifying listeners for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:13.620 11398-11415/io.ionic.starter D/Capacitor/BluetoothLe: No listeners found for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:14.612 11398-11415/io.ionic.starter V/Capacitor/BluetoothLe: Notifying listeners for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:14.612 11398-11415/io.ionic.starter D/Capacitor/BluetoothLe: No listeners found for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:15.653 11398-11415/io.ionic.starter V/Capacitor/BluetoothLe: Notifying listeners for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2021-08-04 17:49:15.653 11398-11415/io.ionic.starter D/Capacitor/BluetoothLe: No listeners found for event notification|E8:EB:1B:53:D0:99|49535343-fe7d-4ae5-8fa9-9fafd205e455|49535343-1e4d-4bd9-ba61-23c647249616
2

I’m probably flirting with an embarrassing situation here, because I’ve never used this plugin and know that its developer @pwespi is relatively active here on the forums, so they will know exactly who gave you this potentially braindead advice, but at first glance it appears that your situation may be related to open issue #70.

1 Like
3

I think I locate the issue.

The UUID must be lower case, otherwise, the listener list cannot locate the listener.

image
image1727×487 74.2 KB

1 Like
4

Yes, this is indeed related to issue #70 and @majianjia found the problem. The plugin used to expect lowercase UUIDs. With the latest release it can handle both lowercase as well as uppercase UUIDs. Thanks for debugging @majianjia .

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