charliebruce/cobble

Common bindings for Bluetooth LE

Hi there 👋

cobble's Issues

Fix Indication on Windows

Currently, Windows will assume that a characteristic will use Notification. If the characteristic only supports Indication, it won't work correctly.

Support write with reply

Currently, the API doesn't allow you to choose between writing with vs without reply. This causes issues with Nordic DFU (which only seems to work if you allow a reply).

Improve MTU on Windows

#6 introduces MTU but just uses the default 20 bytes. We should read from the OS and/or negotiate the maximum.

Handle Android location permission requirement

On Android versions below 12, even if Bluetooth is enabled, if Location permission is disabled no scan results will be provided to the app.

Connection process on Windows is flaky

Quite often, service discovery will fail, and/or a rapid sequence of connection and disconnection events will be fired.

Some possibilities:

• Misunderstanding about event_token, when we need to add/remove listeners
• Lack of understanding re connection/object lifecycle and when connection is closed (when object is deleted?)
• Issue with the GattSession usage
• Uncaught async exceptions
• Leftover connections meaning that callbacks are missed because we're already connected

Approaches:

• Add error handling to async code
• Add a load of debug statements to Bluetooth LE Explorer or similar, and see what it's doing and in which order

Linux support

BlueZ is a work in progress.

• Scanning
• Investigate / confirm socket vs DBus API - rumble implies socket preferable, bleak uses dbus
• Connecting
• Subscribing to notifications
• Reading and writing characteristics
• Work around Battery service issues that may come up as discussed here - some BlueZ versions hide BAS under org.bluez.Battery1 rather than exposing the raw data.
• Tidy up / reliability / edge cases tested - correctly closing sockets, handling disconnections etc

Improve MTU on Android

#6 introduces ability to read MTU, but on Android we just use the minimum of 20 (guaranteed by Bluetooth spec) for compatibility. We should instead read from the OS and/or request a better value if it doesn't automatically select the maximum possible.

Document and streamline development process

• Change export directory structure for easy export into a Unity project
• Document and explain the manifest settings required for macOS/iOS/Android
• Possibly, abstract out the process of requesting permissions on a given platform?
• Tidy up and test the example bindings

Fix indication on Android

Currently, Android will assume that a characteristic will use Notification. If the characteristic only supports Indication, it won't work correctly.

Possible fixes for Android 14

Need to add RECEIVER_NOT_EXPORTED flag here? Possibly wrap in a ContextCompat?

https://github.com/charliebruce/cobble/blob/3e862f0efbf885978a17cefe57013ff60fedf2f7/src/platforms/android/AndroidBLEImpl.java#L136C9-L136C9

processQueuedOperations on Android not thread-safe

operationInProgress might change during the call to processQueuedOperations - this could cause issues?

Remove the operationInProgress and make the processQueuedOperations function synchronized?