I am starting my app development using Xamarin and BLE technology.
What I want end of the day is able to use iOS and Android as beacon device to transmit and receive signals from app. And then when in near or proximity, app should detect that.
I searched and found key things are:
1. IOS: IBeacon, inbuilt in OS
2. Android:
2.a Altbeacon
2.b Estimote
2.c Eddystone
my questions are:
1. Any app or sample where using C# i can achieve BLE transmitter and receiver
2. Which SDK i should use in android to achieve the same?
Thanks.
You can use the iBeacon format on both Android and iOS. The other formats work equally well on Android, but iBeacon has much faster and more reliable detections on iOS.
With Xamarin, you can use this project to bind to the Android Beacon Library:
https://github.com/chrisriesgo/Android-AltBeacon-Library
Related
After days of research and trial and error my colleagues and I have to hope that the StackOverflow community has a working solution.
We got an Android Smartwatch. We developed an app which acts as the BLE central. The App shows a QR-Code encoding an UUID which is unique for every Smartwatch. While showing that QR code it's actively scanning for a device advertising a service with that UUID.
We also developed an iOS app which can scan that QR code and start advertising with the service UUID it received. The Android Smartwatch then connects very quickly to the iOS device.
One purpose of the Smartwatch is to show push notifications from the iOS device. So when the connection is successfully established, the Smartwatch-App subscribes to the ANCS Data Source and Notification Source characteristics. This initiates "Just Works" pairing, so you just have to click on "Pair" on the iOS device. Afterwards you have to allow that iOS notifications are shared to the Smartwatch and then the Smartwatch successfully receives notifications.
ANCS is also the reason why the iOS device MUST BE in the peripheral role.
Until here everything works fine.
When the user leaves the bluetooth range or dis- and enables bluetooth on the iOS device, an automatic reconnect should be triggered. It DOES reconnect when the iOS app is in foreground. Unfortunately it DOES NOT work when the iOS-App is in background. This is probably related to the fact, that the iOS device is not advertising with the required UUID when the app is in background as described in the CoreBluetooth documentation:
All service UUIDs contained in the value of the CBAdvertisementDataServiceUUIDsKey advertisement key are placed in a special “overflow” area; they can be discovered only by an iOS device that is explicitly scanning for them.
We tried many different ways to reconnect from the Android Smartwatch to iOS. From my understanding it should be working when making the first connectGatt with autoConnect=false and when the connection is lost, calling connectGatt on the lost device with autoConnect=true, but it never reconnects. At least not within 15 minutes. Scanning again also wouldn't work, as the UUID is not advertised in background anymore.
We also tried to additionally let the Android device act as peripheral, so the iOS can connect to it. After connecting we wrote data to an "INITIATE_ANCS"-characteristic and let the Android device call connectGatt on the device which was passed to onCharacteristicWrite. This led to interesting behavior:
- The connection was working, we could read a Smartwatch-Characteristic from iOS.
- When subscribing to the ANCS characteristics, it initiated pairing. But instead of "Just Works" pairing it showed a 6-digit code on the iOS device which we had to type onto the Smartwatch.
- The pairing was inititated on every new connect and it always created a new device in the systems device managers on both Android and iOS.
- The pairing WAS NOT inititated when the iOS app was in background.
We really did a thorough research and couldn't find a solution. Did we understand something wrong on how BLE for iOS and Android works? We really hope to find an expert here that has the knowledge what has to be done to make the reconnect work.
Edit:
The Android device is running on Android 5.1.1 and currently it's no option to update.
The iOS testing device is running iOS 13.3 and it should be compatible with iOS 13+
I have traied meny examples to connect Zebra IMZ320 Blutooth using Iphone on Xamarin Cross-Platform
I followed CoreBluetooth Namespace
enter link description here
and also using Plugin.BLE
but I couldnt connect my device eny one has success experience in connect Bluetooth printer using Xamarin cross platform ios
CoreBluetooth.framework is for Bluetooth Low-Energy:
Communicate with Bluetooth 4.0 low-energy devices.
The Core Bluetooth framework provides the classes needed for your apps
to communicate with devices that are equipped with Bluetooth low
energy wireless technology.
According to the specifications of the Zebra IMZ320, the communication mode are:
Secure Bluetooth 2.0, 802.11a/b/g/n (optional) or USB (client)
connectivity; Wi-Fi®-certified connectivity
That is not Bluetooth Low-Energy (which has been introduced in Bluetooth 4.0). You won't be able to find the printer with a Bluetooth Low-Energy scan, because the behavior, logic and implementation (protocols, norms, GATT, Peripheral/Service/Characteristic) are totally different.
Also, the description page of the Zebra IMZ320 gives a link (FAQ - Creating & Registering An IOS App) to how develop apps for it.
You need to use ExternalAccessory.framework for it.
If your app communicates with a Zebra product via Bluetooth using the
External Accessory Framework, and you plan to distribute the app via
the App Store or Volume Purchase Program Store, then you must register
the app with Zebra.
This page is general (and not specific to that printer). But according to the specs, it's not Bluetooth Low-Energy compliant (while others products might be, that's why there is a paragraph talking about CoreBluetooth in it).
That's normal behavior (using ExternalAccessory vs CoreBluetooth framework), because each one of them has a specific meaning and use.
Conclusion:
Use ExternalAccessory.framework, it is also available on Xamarin.
For example, if there is a gaming console (i.e PlayStation) connected to HDMI input in a TV with Android TV. Then, is it possible to record the video going through this HDMI input with a 3rd party app?
In my question I'm referring to Android's TV input framework
Thanks for the helpers.
The TV Input Framework docs mentions that it supports TV recording APIs.
DVR
For devices on Android 7.0 and above, the TV App must support the
Android framework TV recording
APIs,
to support, list, and play recorded programs.
This allows device manufacturers to plug their DVR subsystems into TIF
and dramatically reduce the integration effort it takes to enable or
integrate DVR functionality on a TV device. It also enables third
parties to provide aftermarket DVR systems that can be plugged into an
Android TV device.
In addition to recording live content, the TV App also handles
resource conflict. For example, if the device has two tuners, it can
record two programs at the same time. If the user asks to record
three, the TV App must handle the conflict and should either surface a
notification or request that the user schedules a priority for these
requests.
However I don't have code samples for you as I haven't experimented with this yet.
Another approach would be to use the MediaProjection API and record this with a MediaRecorder. Jake Wharton's app Telecine follows this approach and you can find the source code on GitHub.
The benefit is that these APIs were introduced with Lollipop, so you can use them on all Android TV devices. However I just started experimenting with Android TV, so I can not tell from personal experiences.
I have a sensorTag device and I want to start using it without implementing the bluetooth connectivity layer, what is the easiest way to use it in swift?
The easiest way to connect to sensorTag (and other devices) in swift is to use
the IBM Mobile Wearables SDK
you can read about it here:
http://wearables.mybluemix.net/
and get it for free here:
https://github.com/ibm-wearables-sdk-for-mobile/ibm-wearables-swift-sdk
I would like to detect a beacon and then write a value to some of its GATT characterictics, so other BLE-devices can read it. Is this possible at all? Or some special device is needed for this?
This is not possible with a standard iBeacon because it is a transmit only device.
You might be able to build your own custom device to do this, but making it work on iOS when more than one Bluetooth device is around will be almost impossible. This is because there is no way to correlate detected iBeacon identifiers with as connectable Bluetooth device -- iOS has sandboxed the CoreLocation iBeacon detection APIs and the CoreBluetooth APIs needed to read and write GATT characteristics.
As a result, you can never know for sure if you are writing to the same device you detected.
For a detailed explanation of the sandboxing of the CoreBluetooth and CoreLocation iBeacon APIs, see here.