cordova-plugin-ble-central

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I have a weird problem with the BLE connection. It doesn't disconnect when I quit the app or when Bluetooth is turned off. Not even when restarting the tablet during the app is connected. But it works with other bluetooth apps. So I guess it's a problem with this plugin or Cordova.

I don't know exactly how low-level bluetooth works. How does a disconnect work? Specifically when exiting the app that made the connection or how it works when bluetooth is off. If I see that correctly, an event is sent during these actions (exit app / switch off BT). But not sure? I just wonder, why does it work with other apps like "nRF Connect"? Only when connecting with the Ionic / Cordova app with this plugin causes this problem.

Any guesses / ideas / experiences?

I'll do more test about this issue. I create a new app and test the connection. My current solution is a custom heartbeat sent every seconds. And a timeout causes a disconnect. But I don't want such special implementation. (Which also brings other problems.) ...

Versions: cordova-plugin-ble-central: 1.3.1 @ionic-native/ble: 5.30.0 @ionic/angular: 5.3.2 cordova-android: 9.0.0 cordova-plugin-androidx-adapter: 1.1.1 Android: 7

config.xml (snippet):

<preference name="ScrollEnabled" value="false"/>
<preference name="android-minSdkVersion" value="24"/>
<preference name="BackupWebStorage" value="none"/>
<preference name="SplashMaintainAspectRatio" value="true"/>
<preference name="FadeSplashScreenDuration" value="300"/>
<preference name="SplashShowOnlyFirstTime" value="false"/>
<preference name="SplashScreen" value="screen"/>
<preference name="SplashScreenDelay" value="10000"/>
<preference name="LoadUrlTimeoutValue" value="60000"/>
<preference name="AndroidXEnabled" value="true"/>
<!-- ... -->
<edit-config file="AndroidManifest.xml" mode="merge" target="/manifest/application" xmlns:android="http://schemas.android.com/apk/res/android">
  <application android:usesCleartextTraffic="true"/>
</edit-config>
<config-file target="AndroidManifest.xml" parent="/manifest" xmlns:android="http://schemas.android.com/apk/res/android">
  <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
  <uses-permission android:name="android.permission.INTERNET"/>
</config-file>

Please let me know if I should provide more info. At this moment I'm doing more tests on this issue.

Update: I've created a new Ionic app from scratch. I cannot reproduce this issue. Argh... That's really strange. Ok, in my test app I only scan and connect. In my production app I subscribe to notifications and receiving a lot of messaged. So maybe this is the problem. Disconnect on app close / bluetooth off / tablet off does not work when notification (indication) started. But why? The connection will not be terminated if the app is closed or if Bluetooth is disabled when notifications have been subscribed. At this moment it's no clear if this is an Android bug or an issue of this plugin or peripheral. ...

I've addressed part of this in https://github.com/don/cordova-plugin-ble-central/pull/845, which will close the connections on app destruction.

The issue with the connections not being closed when Bluetooth is disabled is slightly different. Are you able to confirm how you know the connection is being held open in this instance?

Under normal circumstances, the connect error callback won't be triggered by disabling Bluetooth as it's not the peripheral that has terminated the connection, but the phone itself.

I'm seeing this issue too.

Is there a way to detect the plugin is already connected?

I don't want to have my users have to force close the app.

This plugin is the best on the market, we've extensively tested a few. If only this one bug could be fixed. @peitschie

Is there a way to detect the plugin is already connected?

Just using ble.isConnected(deviceId, success, failure) should tell you if you are already connected to the device. If you just want to try and re-connect, the best approach here is to just call ble.connect(deviceId...) on application launch.

@tigohenryschultz if there are still issues around this, feel free to raise a new issue and we can discuss there.