- "Introduction to Bluetooth Low Energy" by Adafruit.
- "Android Lollipop: Bluetooth LE Matures" - A nice overview video by Dave Smith. Focuses on Lollipop and newer.
- Fragmented Episode 45: "Bluetooth (LE) with Dave (devunwired) Smith" - Another great Dave Smith overview if you prefer the podcast format!
- NordicSemiconductor/Android-BLE-Library - Contains production-ready implementations of many of the important components (queues, managers, etc.) for working with BLE on Android. Consider using this library as-is or browsing the source code as inspiration if building your own implementation.
- Polidea/RxAndroidBle - For using RxJava with BLE.
- Beepiz/BleGattCoroutines - For using Kotlin's coroutines to sidestep BLE callback hell.
- iDevicesInc/SweetBlue (proprietary) - May be useful if you have more dollars than time, or if you are developing stability-critical applications.
- JuulLabs/kable - Coroutines-based Kotlin Multiplatform library.
Resources relevant to building Bluetooth Low Energy Android applications from scratch.
- "Bluetooth Low Energy on Android: Top Tips For The Tricky Bits" by Stuart Kent (slides, video) - My own talk, but now several years old.
- "The Ultimate Guide to Android Bluetooth Low Energy" by PunchThrough - A very modern (2020) comprehensive guide.
- "Bluetooth LE for modern Android Development" series, by Erik Hellman (post 1) - Introductory articles with advice that's particularly relevant in 2021.
- Android BLE Issues - A fairly complete list of symptoms you are likely to encounter while working with Android's BLE stack. Some apply to pre-Lollipop only, but many still exist and occur.
- PunchThrough/ble-starter-android - Source code accompanying the PunchThrough guide listed above.
- NordicSemiconductor/Android-nRF-Blinky - Source code for an Android app that uses Nordic Semiconductor's Android-BLE-Library.
- android/connectivity-samples (BluetoothLeGatt) - A compact
Serviceand broadcast based example.
Android Source Code
- Locations within the AOSP source code where GATT success and error codes are defined:
Useful users, questions, answers, and comments from Stack Overflow's Q&A.
- Emil - A user who consistently provides high-quality and detailed information regarding BLE on Android. Worth browsing their answers!
- "Android 4.3 Bluetooth Low Energy unstable" - In particular, this answer is a great overview and includes a hint regarding Wi-Fi/BLE interactions that I haven't seen elsewhere.
- "How to detect Bluetooth state change using a broadcast receiver?"
- "Difference between close() and disconnect() in Android Bluetooth API?"
- "Android - Could not connect to bluetooth device on Lollipop" - This answer provides some tips regarding the transport type flag passed to
- "Android Bluetooth LE: Not discovering services after connection" - This comment indicates that one should delay calls to
BluetoothGatt.closeuntil either (1) disconnection completes, or (2) a predefined period of time elapses.
- "How to programmatically force bluetooth low energy service discovery on Android without using cache" - This answer formed the basis of my refined service cache-clearing method.
- "Android 4.3: How to connect to multiple Bluetooth Low Energy devices" - This answer discusses the serial nature of the Bluetooth APIs and indicates that things work the same for web and iOS.
- "Android BLE API: GATT Notification not received"
- "RxAndroidBle keeping a persistant connection + Write/Notification handling" - This answer confirms that RxAndroidBle was not designed to accommodate persistent connections. UPDATE: apparently this is possible; see author's tweet here.
- "Location requirement to scan for BLE devices" - This answer provides some context regarding the location permission requirement for scanning.
- "Is the native Android BLE implementation synchronous in nature?" - This answer confirms (from a Samsung perspective) that BLE operations should be performed serially.
- "clientIf field in Android BluetoothGatt class" - Some information on the
clientIfvalue that's logged with almost all Android BLE calls.
- "Why does setCharacteristicNotification() not actually enable notifications?"
- "Android Bluetooth Low Energy Characteristic notification count limit: does this vary by device?" - Clarification that the stack's 15 characteristic notifications limit is a limit per peripheral/server rather than per central/client/mobile device.
(You must sign in with a Google account to access these.)
- "Android 4.3: Bluetooth LE pretty instable"
- "NullPointerException in BluetoothGatt.java when disconnecting and closing" - Includes discussion regarding exactly when
BluetoothGatt.closeshould be called.
- "Emulator and Bluetooth" - Requests the addition of Bluetooth support to Android emulators (via host device Bluetooth).
- "Bluetooth permission request dialog" - Bug report related to weird window pop-up while programmatically prompting user to enable Bluetooth.
- "Get BLE scan result using 'BluetoothLeScanner.startScan' must open Location Service in Android 6.0" - Long thread related to location permissions and services requirements.
- "[BLE] Android does not discover services if device supports Service Changed" - Thread related to service caching and how to skip the cache.