I am writing an android app to connect with BLE heart rate monitor devices.
All works well until another application tries to connect to the same service on the BLE device.
Only one application seems to be able to connect at a time.
Is it possible to connect the same BLE service to multple apps at once?
I set up my Bluetooth service in accordance with Link :
You can use BluetoothManager.getConnectedDevices() to get a list of Bluetooth devices, even ones not connected by your app. Unfortunately, you don't also get the service information for those devices.
What you can do then, is connect to the ones not already connected by your app and perform service discovery on them (BluetoothDevice.connectGatt() / BluetoothGatt.discoverServices()), then disconnect those that you aren't interested in. It's a bit cumbersome, but it seems to work for us.
No you can not do that, this is something is not supported in BLE.
Related
I need to estabilish a brief communication between a BLE master and a BLE peripherical device.
Until I have to use the mobile phone I have no problems, since I select the bluetooth device from Android, I can connect to it and then I can receive data simply writing them to HM-10.
BUT, this approach is battery expensive, since the BLE scanning is more battery expensive than the BLE advertising (right?). So I want that the mobile becames an advertisor and the HM-10 takes the ROLE of Slave.
BUT, I still don't understand if it is possible to connect to other devices: I tried AT+CONN and it always fails (AT+CONF). Is there any way to send brief data from the HM-10 to the advertisor, even without connecting?
Even my firmware looks slightly different from the readme! For example,AT+LN is present in the documentation but it appears to not exist. Does a better version of the firmware for this device exist, or, are sources available somewhere? I installed the HM-Soft V705 (lastest).
Thanks
UPDATE 1:
#ChrisStratton Ok, I have some intresting news: I was already following your idea (phone advertise sometimes, while HM-10 always scan and tries to connect to the service if it sees it, then HM-10 send some data, phone answer). I managed to make the phone visible from HM-10 (don't ask me how!). I am using the BLE Tool Android app to test everything. Now, the central problem now is that HM-10 won't connect to the android service even if the advertisor is connectable (see attached images).
I am sospicious that the AT+CO (that I discovered is a kind a replacement of AT+LN, but I am not sure) can help, but i don't know how.
I would like to ask for your valuable opinion about the following:
I'm developing an Android app that needs to connect with the BLE device (whose name I know) automatically on starting the app. Furthermore, the app should be able to keep the phone connected to the BLE device (there will be no "connect" and "disconnect" buttons on the app screen). In other words, if established connection is lost for some reason, the app should be capable to detect this and to re-connect again. The user of the app don't need to be aware of this background process. For him/her, it is only important that the phone is connected with the BLE device.
Simply speaking, I know the name of the BLE device (it is called 'HMSoft'). How should I keep the app connected with this BLE module? Should I use some Thread that will do the job for me in parallel with my other activities within the app MainActivity? Or there is some better approach? Did you have similar experience in the past?
Thank you very much for your time and effort. I really appreciate it.
Sincerely,
Bojan.
You will want to wrap the BLE implementation up in a Service. Within that Service, you will have to implement the logic to connect to the BLE device and keep trying to connect to that BLE device if it becomes unavailable.
I am no Bluetooth specialist and wondering what possibilities are available to find already paired Bluetooth devices automatically when they are range of each other.
Background:
In our case an Android application needs to connect to a dedicated accessory via Bluetooth (Rfcomm). Both devices are known to each other (they are paired). The Android application registers a broadcast receiver. During the startup of the application, the app initiates a discovery to find the dedicated accessory. If the accessory is in range everything works great.
Problem:
The user starts the application outside the range of the dedicated accessory. The Android application tries to discover the accessory without success. Then the user goes into the range of the Bluetooth accessory. The broadcast receiver won’t get notified about the accessory that is in range now.
Similar Thread / Possible Solutions
Similar questions were already asked on stackoverflow (e.g. autoconnect to bluetooth device when in range).
But continuously trying to discover Bluetooth devices in range isn't what I am looking for because this would cause too much battery drain of the Android device.
Another solution would be to try to connect to the paired device in the onResume method of the Activity. This would work but has the disadvantage that the application can’t run in the background. So the user had to bring the application at least once to the foreground to initiate the connection.
A third idea I thought about is to implement a server socket into the Android application too. When the android application is started and the discovery finished without success, the Android application could create server socket and to listen to incoming notifications of the accessory. This would help in some scenarios (e.g. the user starts his application, approaches the accessory, activates the accessory and the accessory notifies the application on startup that it is in range now). But this is still no 100% solution because both devices can start outside the range of each other. Also it would be mandatory to implement additional functionality (Bluetooth server socket in the Android device…).
So I am wondering if better solutions exist. I am looking for a solution where no additional ServerSockets are required and I always get the notification that the two already paired devices are in range of each other :-)
Thanks for any help!
After connecting the device for the first time, keep the mac address in a local list.
On disconnect, use connectGatt with autoconnect set to true to automatically re-connect when you are in range.
Not a full solution, but maybe it's sufficient for your app to poll the accesory's presence whenever the screen is turned on? In that case, this may be helpful: Start Activity on wake up/sleep in Android
I have an android app, it does the following:
Connects with a server to read and update a database at the same time as others.
I want to convert this to an app that does not need an internet connection. Therefore i would like to know if its possible to have an android device acting as the server with the database, whilst multiple phones connect to it via bluetooth getting and updating the information in the database?
Thanks
Yes. It possible.
However all of your devices will have to be located nearby, so they can connect to each other through bluetooth.
You can take a look at Android Bluetooth API.
However, my recommendation would be to use Wifi instead of Bluetooth. YOu will need additional WiFi router. However, you won't need to deal with Bluetooth API in such case.
You will only need to write a server on one of Android device and the rest of devices will work the same (as now)
There are a few options to doing so, that don't involve a server. Both of them require a slightly different approach than both devices connecting to a server.
Wi-fi Direct- Only available with Android 4.0+.
Bluetooth
Personally, I have been using the Bluetooth option, and not found it terribly difficult. Essentially, you have to do the following to make it work.
Have one of the devices listen for a connection. If it is unpaired, you will have to make the device discoverable.
The second device needs to initiate a connection. It can do this by looking at the known devices and trying to connect to one, or listening for a new device
After the two devices connect, they must initiate some kind of a communication protocol. The communication is essential a serial connection.
Blue-tooth requires that the devices be within about 10 m of each other. Wi-fi direct will allow somewhat further, but as mentioned, is less supported. It is possible to allow for both communication methods, but is somewhat challenging.
I am currently working on the creation of an application for mobile devices with Android which should be capable of sending and receiving messages through local means like wifi and bluetooth. After making a research about it I found out that Android doesn't have a native wifi ad hoc functionality and that the only way to achieve that is through rooting your device and patching the wpa_suplicant and some other similiar methods which are not generic for every device.
Synopsis of what I am trying to achieve:
An application for Android that scans for devices nearby and tries to connect to them automatically. If the other device also got this application isntalled then it automatically accepts any connection request it receives and when the connection is established it sends back a message which ensures that it has this app installed so that both can start exchanging messages automatically and the users don't have to allow/deny any of the sending/receiving in real time.
My questions are:
Is there any way of sending messages through wifi between 2 android
devices without the use of internet?
Since Ad Hoc is not supported, is there any alternative?
In case the answer to 2 is no , then is it possible to make one of
the devices to be an access point so the other can connect to it and
vice versa.
As for bluetooth, is it possible to skip or automate the allow/deny
pop up of an incoming connection and the pairing procedure?
I'll be glad if you could give me an answer to those and/or any suggestions.
You'll be able to communicate between two devices over wifi without a router/access point using Wifi Direct (P2P) in Android 4.0.
Otherwise, I don't believe you can achieve this over Wifi (bluetooth would be the next best alternative). Since 2.2 you can set your phone up to be a Wifi Access Point (for tethering your device's network connection), but during this time, the Wifi hardware is unavailable for normal use. If you had 3 devices it could work (1 AP, 2 connecting to it).
Is this for a constant connection, or a one-off small delivery? You could use NFC if you want to transmit a URL for example (Android Beam integrates this type of sharing in Android 4.0, but could implement it in 2.3).