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The Ultimate Guide to Android Bluetooth Low Energy | Punch Through
3/02/ · Introduce app-layer security to protect the data flowing between devices and a BLE app; Setup the optimal size for transferring data to/from a BLE device; Bluetooth LE Android apps. Android BLE app development has its quirks: Use Android API level 21 or newer (Android +) Avoid using private APIs (as they will not work on Android 9+) 15/05/ · If BLE hardware is a requirement for your app, you can optionally declare that your app uses BLE features on Android devices. By doing so, users on devices without BLE capabilities won’t see your app on the Google Play Store. If this behavior sounds good to you, add the following snippet below the tags 15/04/ · BLE complete example link to github - contains Android, iOS, ESP32 - 2 apps for each platform, Central and Peripheral. Each Central is compatible with each Peripheral. This is a great guide: The Ultimate Guide to Android Bluetooth Low Energy by PunchThrough. About your second question (that automatic disconnection occurs), I remember I've noticed similar disconnections on iOS, but
Downloadable android ble app example
With its ability to consume very little power yet still provide the connectivity to communicate with small devices, more and more people are looking to hop downloadable android ble app example the Bluetooth Low Energy BLE bandwagon for Android apps. For new readers not familiar with who we are and what we do, we are Punch Through: an engineering consulting firm specializing in firmware, software mobile, and hardware solutions that help engineering leaders and teams through the complex journey of building a Bluetooth product.
Most code snippets were written in Kotlin, but they translate well over to Java too. All the code snippets in this post aim to showcase how a given Downloadable android ble app example operation should be performed.
The actual, full implementation in the context of an example app is available as an open source GitHub repo. A BLE device can typically run on a small battery for weeks, if not months or even years, making it perfect for sensor-based or Internet of Things IoT use cases. Another important distinction between Bluetooth Classic and BLE is that BLE is far more developer-friendly. BLE opens up a world of endless possibilities by allowing developers to specify various custom profiles for different use cases, whereas Bluetooth Classic primarily supports the Serial Port Profile SPP for sending custom data.
The Android Bluetooth API is also not very straightforward to work with for Bluetooth Classic use cases due to the following reasons:. Your Android device acting as a central can connect to multiple peripherals external BLE devices simultaneously, but each BLE device acting as a peripheral can typically only interact with one central at a time.
It helps to also think of the relationship between a BLE central and peripheral as a client-server relationship. The server peripheral hosts a GATT database that provides information which the client central accesses via BLE. This post aims to provide a high level overview of how to perform BLE operations, so that you can read and follow along as you code.
A full example implementation is available on our open source GitHub repo. For downloadable android ble app example that utilize the BLE APIs, we like to go with Kotlin as the main language and we support a minimum API level of 21 Android 5. Check out our Android architecture post for more information on why we made these choices!
xml via the Project tool window. Out of the 3 declared permissions, only the location one is considered — in Android terms — a dangerous permission. What this means is that while the Bluetooth-related permissions are automatically granted to the app during install time, the user needs to explicitly grant location access to the app.
If BLE hardware is a requirement for your app, you can optionally declare that your app uses BLE features on Android devices. It can be any positive integer value:. When your first Activity is about to show with these additions, we check if the BluetoothAdapter is enabled. At this point, take the time to build and run the app on a physical Android device. If you dismiss the dialog, the dialog goes away without doing anything. We can do this by overriding onActivityResult and checking the requestCode and resultCode :, downloadable android ble app example.
In our code snippet, what this allows us to do is to keep displaying the same alert over and over again until the user accepts our recommendation to turn on Bluetooth. The following property and extension function combination does just this:. Meanwhile, downloadable android ble app example, the hasPermission function is an extension function on the Context object, meaning each Context instance with access to this extension function can call it and use it as if the function was part of the original class declaration.
Depending on how you structure your source code, the hasPermission extension function may reside in another Kotlin source file so that it can be accessed by other Activities as well. Since the location permission is only needed while performing a BLE scan, downloadable android ble app example, it makes sense that we should only prompt the user to grant this permission when they want to initiate a BLE scan. startBleScan will essentially check to see if the location permission has downloadable android ble app example granted before allowing the user to proceed with performing a BLE scan.
startBleScan will call requestLocationPermission if the Android runtime is version M and above, and location permission has not yet been granted.
into an Activity extension function to make this more reusable and readable. You can opt to call ActivityCompat. directly if you so wish! Unless the BluetoothDevice handle was cached from a recent scan, we need to perform a BLE scan before we can connect to a BLE device.
A typical BLE app connection setup flow looks like this:. The ScanFilter class allows us to filter incoming ScanResult s based on:. While some apps do have use cases for scanning without a ScanFilter our very own LightBlue app is one of themmost apps use BLE to connect to a specific type of device because they are designed to perform certain meaningful tasks with only that type of device. For example, an app that shows the current temperature, humidity, and air pressure would only try to connect to BLE devices with those capabilities, like devices that advertise the Environmental Sensing Service.
We can create a ScanFilter using the ScanFilter. Builder class and calling its methods to set the filtering criteria before finally calling buildfor example:.
Based on our experience developing BLE intensive apps for our clients, if a custom firmware is involved in any way, the easiest way to make sure an app only ever picks up devices running said custom firmware is to generate a random UUID, and have the firmware advertise this UUID.
The downloadable android ble app example then performs scan filtering based on the UUID, and since UUIDs are unique enough for practical purposes, we can expect the scan to only pick up our devices of interest.
method, and generally the things we care about in a ScanResult are:. Aside from scan results filtering, Android also allows us to specify the scan settings to use during scanning, represented by the ScanSettings downloadable android ble app example which also comes with its own ScanSettings. Builder builder class. Here are a few practical and commonly used scan settings that Android allows us to tweak:, downloadable android ble app example. If your app went beyond this limit, the scan would appear to have started but no scan results would get delivered to your callback body.
After 30 seconds have elapsed, your app should call stopScan followed by startScan again in order to start downloadable android ble app example scan results — the old startScan method, and is vaguely described as the app failing to register with the BLE scanner. The undocumented solution to this is to request for the user to disable and re-enable Bluetooth on their device.
If this fails, which it mostly does, the next and only thing to do would be to ask your users to perform an Android reboot. Oh, joy! bluetoothLeScanner is because bluetoothAdapter — itself a lazy property — relies on the getSystemService function, which is only available after onCreate has already been called for our Activity, downloadable android ble app example.
By deferring the initialization downloadable android ble app example bluetoothAdapter and also bleScanner to when we actually need them, we avoid a crash that would happen if bluetoothAdapter was initialized before onCreate has returned. Before we can start scanning, we need to specify the scan settings. With all the pieces in play, we can finally modify our startBleScan function from earlier to actually perform a scan:. To stop an ongoing BLE scan, BluetoothLeScanner provides a stopScan method.
There, done and done! Run the app once again, and verify that your app now has the ability to start and stop a BLE scan. Adapter class and your layout XML for each scan result. Instead, you can find our example implementation here. Next, we want to correctly populate our scanResults property whenever a new BLE scan result comes in. In order to keep the UI up to date with the latest RSSI readings, we first check to see if our scanResults List already has a scan result whose MAC address is identical to the new incoming ScanResult.
If so, we replace the older entry with the newer one. Take some time to build and run the app on your Android device, and you downloadable android ble app example see your RecyclerView being populated by scan results representing BLE devices in your vicinity. The typical flow for initiating a BLE connection in apps can be broken down into roughly two types:. Our example for this section assumes a use case of manual connection.
Regardless of which use case your app falls under, you should always stop your BLE scan before connecting to a BLE device. Doing so saves power and more importantly — in our experience — also helps increase the reliability of the connection process. The connectGatt method on a BluetoothDevice handle will be used to initiate a connection with a BLE device. The reason: this version of connectGatt is available as early as API level 18, and we intend to work with a minimum API level of 21 Android 5.
The other overloads are available only from API level 23 or In our experience, setting the flag to true may result in a slower than usual connection process if the device is already discoverable in the immediate vicinity, downloadable android ble app example. Our preference when developing BLE apps is to set the flag to falseand instead rely on the onConnectionStateChange callback to inform us on whether the connection process succeeded.
In the event of a connection failure, we can simply try to connect again with autoConnect set to false. All variants of connectGatt The connectGatt method mentioned previously also takes in an object called BluetoothGattCallback, downloadable android ble app example. The main callback method we need to implement at this stage is onConnectionStateChangewhich provides crucial information on the status of the BLE connection. This is the source of truth for connection and disconnection events pertaining to a given BLE connection.
This will be the main interface through which we issue commands to the BLE device. We strongly believe Google can do better here. Regardless of which error status code you got in your onConnectionStateChange callback, the recovery flow typically goes like this:.
The following code gets called when the user taps on a BLE scan result displayed in the RecyclerView :. Note the TODO in the success branch, we want to store a reference to the BluetoothGatt object here.
Run your app, start a BLE scan, and tap on a scan result. Check Logcat to see the outcome of the connection attempt, and optionally retry if it failed the first few times. If you made it this far, congratulations. Your app can now connect to BLE devices! Service discovery is essential after establishing a BLE connection with a device.
Since a service is a collection of characteristics, and each characteristic can have descriptors defining downloadable android ble app example attributeswe can think of each service as a floor or level in the mall, a characteristic as an individual store on a given level, and a descriptor as specific aisles or sections in a given store.
Performing service discovery is straightforward. Using the BluetoothGatt object we saved from a successful connection attempt, we simply call discoverServices on it:. Consider the following modifications to our BluetoothGattCallback property:.
With this change, each successful connection will automatically result in service discovery on the BluetoothGatt object before connection setup is considered complete. They want to call some connect function and be done!
Bluetooth – Android Studio Tutorial
, time: 26:15Downloadable android ble app example
3/02/ · Introduce app-layer security to protect the data flowing between devices and a BLE app; Setup the optimal size for transferring data to/from a BLE device; Bluetooth LE Android apps. Android BLE app development has its quirks: Use Android API level 21 or newer (Android +) Avoid using private APIs (as they will not work on Android 9+) 15/04/ · BLE complete example link to github - contains Android, iOS, ESP32 - 2 apps for each platform, Central and Peripheral. Each Central is compatible with each Peripheral. This is a great guide: The Ultimate Guide to Android Bluetooth Low Energy by PunchThrough. About your second question (that automatic disconnection occurs), I remember I've noticed similar disconnections on iOS, but 7/06/ · android-ble-sample. Creates a simple bluetooth low energy connection using android apis. Searches for your ble device name and shows device not found after iterating through 5
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