I’m trying to develop an Android application for a medical device using Bluetooth (SPP). I’ve used the BluetoothChat as a starting point (also see earlier post). Now I think I’m facing a weird problem and I’m also having trouble describing it. Testing on a Nexus S.
Upon the completion of measurement the medical device checks its memory for the Bluetooth address and other information about the previously paired device. If found it will try to initiate a connection (while the application on the phone is listening for a connection) and then transfer data and otherwise it starts an inquiry procedure.
The first time it works fine: pairing procedure, establishing connection and transferring data. When the data is received the application replies with an ACK package and the connection is terminated.
The rest of the times it does not work: after a measurement I can see in the LogCat that the phone receives a signal (just like the first time) from the device, so I know the device saved the phones Bluetooth address. It seems like the system ignores the signal (or at least nothing happens), no connection is established and thus no data transferred even though I'm using accept-method of BluetoothServerSocket the same way as when it works. If I remove the pairing record from the phone this signal starts the pairing procedure and the devices get paired again, BUT they still won’t establish a connection nor transfer data. I guess the message about the signal represents a try to establish a connection but something is wrong. The message in the log is the same as when the connection is successful and can be seen in the LogCat:
03-22 14:21:55.335: ERROR/BluetoothEventLoop.cpp(114): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/4123/hci0/dev_00_A0_96_2D_05_E8
It's rather confusing it's an ERROR message and present in the log when it works as well.
The weird thing is that it works the first time they are successfully paired, but never again afterwards. When the data is transferred and the device receives an ACK it saves the Bluetooth address "and other useful information". The only way I can reproduce the successful ‘first time’ is by pairing the medical device with another device and then afterwards pair it with the application on the phone again.
I’m confused about what is actually causing this problem. Does anyone out there have any clue?
I’m afraid my problem is a bit to specific to be familiar to others if case the problem is caused by the medical device and not the phone. I was thinking it might be related to the Link Key or Channel? But on the other hand, as I said, if I remove the pairing from the phone, I'll get a pairing request again.
The medical device is old, using Bluetooth 1.2. Now it strikes me that I should have a look at if there are any connection-related issues because of this. Could it be that a device using Bluetooth 1.2 have another policy of what information to store when it is paired?
For the moment I feel I'm struggling with a problem I don't fully understand, but if I'll understand later I'll of course get back with my conclusions. I hope I didn't forget important details.
Thanks in advance /F
Hi fredricus My problem is similar to yours i m running a bluetooth service which keeps on listening for data when the bluetooth is on.u have solved the problem of connecting android device to a medical device as u mentioned that u have used reflection.But in case if medical initiates connection will it be able to connect to android device.
Sounds like the problem is with the medical device, that it is not able to re-establish connection (i.e. re-authenticate) with already paired device.
I dont think that being being 1.2 should matter. The procedures are designed to be backward compatible so that all bluetooth versions work with each other.
You may have to get a bluetooth sniffer trace to check what might be going on over the air that will validate if the issue is on the medical device side.
Another option is to check if android has any way to turn on more detailed logging of the Bluetooth interactions and enable that. Default log of Android messages are very high level and does not provide much detail
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 have made an app on iOS and Android that can connect to a BLE device. I connect to the "device by service" and things work well.
A customer is asking me why the device is not showing in the list of bonded bluetooth devices. I didn't need pairing to connect because I found code that didn't require it, but now that I think, I wonder :
What would be the benefits to have a paired device ?
Would it connect faster ? Hold connection better ? ...
Security, mainly.
Sending data to a non-paired device requires that the device be discoverable and open to receiving data from random devices. This isn't always the case for reasons of security, and so many devices ship with both disabled.
The attack vector is something like this: you'll always have to pick a device in the list of discovered devices. It's not too difficult to create a device with "<CEO>'s iPhone" as the name and wait until he tries to send the secret memorandum to his iPhone, then intercept it.
Additionally, bluetooth stacks have been known to have vulnerabilities that can be exploited by sending data to the device, which was made more problematic by devices auto-accepting data without confirmation.
Paired devices create a pre-existing relationship between the two, allowing your user to be notified when something out of the ordinary happens. This is always a good thing.
It is indeed also true that not having to go through device discovery (which may take up to a few seconds) improves performance when doing the initial connection setup, but I wouldn't see that as the major reason.
i am working on an android app in which I need to only listen for incoming devices an log the data they are sending using Bluetooth, device sending data is basically a digital Bluetooth enabled thermometer which just sends the data. Problem is i don't know where to start as i m new to android programming. Just a step by step Procedure would be enough to guide me on the right track . i tried Bluetooth chat example but i didn't took me any where also i wasn't able to understand it.
Regards,
Rafiq Ahmed
First thing you need is to know how to make the connection with the thermometer. I suppose that, since the device is paired to the smartphone, you only must to manage the connection as a server (On the android-phone). Here you got a summarize:
Change Bluetooth permissions:
http://developer.android.com/guide/topics/connectivity/bluetooth.html#Permissions
Enable and set up the bluetooth: http://developer.android.com/guide/topics/connectivity/bluetooth.html#SettingUp
Find the device: http://developer.android.com/guide/topics/connectivity/bluetooth.html#FindingDevices
Connect with it: http://developer.android.com/guide/topics/connectivity/bluetooth.html#ConnectingAsAServer
And manage the connection:
http://developer.android.com/guide/topics/connectivity/bluetooth.html#ManagingAConnection
And last thing, I recommend you to pair the device before running the application, at the adjust menu of your mobilephone. Since that, follow the previous steps and all will be fine. If you have some doubt ask me, I had the same troubles about bluetooth connections with arduino and HC-06 bluetooth device
Hope it helps
I'm asking because I've been facing that issue for weeks.
I need to develop an Android application that can be able to perform an Bluetooth Connection and send data to an Bluetooth Hardware.
Ok, so here's the point:
is it possible to perform a RFCOMM connection to an 'unknown' device?
I mean, is it possible to do this without having any information about the hardware code?
Because i'm only able to modify the AndroidDevice (cellphone) code, for SENDING purposes.
I want to send a byte and make sure it was received, but there's only a sending code.
Could we have some more details? Is the other device accessible by you, as in can the other device know information about the Android device? And what do you mean by a "sending code"?
The Android device can pick up any active Bluetooth device in its range, and know the name and address of those devices. So, if the Android device doesn't know anything about the Bluetooth device it wants to connect to, you can always sort through the list of devices in range, and get its hardware code through that.
See the documentation about Bluetooth, specifically the Finding Devices section:
http://developer.android.com/guide/topics/connectivity/bluetooth.html
I've done a fair amount of Bluetooth work with Android devices and Arduinos, and the Bluetooth library might be a bit of a pain to work with, but it is powerful.
With bluetooth the two devices have a UUID. If you a writing a program that runs on both devices you have them listen for that UUID. When they connect as a client or a server you have a dataInputStream and a dataOutputStream. Then you can push and pull bytes out of those.
I'm attempting to adapt the BluetoothChat example that comes with the SDK to a single-server, multiple-client configuration. I'm having issues and hope someone can help.
I've created two distinct apps, a server and a client, rather than have a single app function as both server and client, as in the example. So the upon starting the app, the server creates a bluetooth service, which creates a new AcceptThread, which listens for incoming connections. I made a couple of modifications to the example code so that the AcceptThread continues to listen, even after the first connection is made (the example stops listening after the one connection is made, because it only needs to establish connections between two devices). I created an ArrayList to handle the multiple connections. Each time a new connection is attempted from a remote device, a new ConnectedThread is created and added to the list.
The first client connects just fine.
When the second client attempts to connect, the connection fails. The log output is:
D/BluetoothEventLoop( 140): Device property changed: <device address> property: Connected value: true
I/BluetoothService( 140): ACL connected, mAclLinkCount = 2
D/BluetoothEventLoop( 140): Device property changed: <device address> property: Connected value: false
I/BluetoothService( 140): ACL disconnected, mAclLinkCount = 1
So it looks like the second connection attempt is successful, but then it is immediately disconnected. This looks like it's happening at a low level, outside anything the code is handling. This happens with a number of different types of test devices, so I don't think it's due to a particular firmware or hardware issue.
Can anyone help with this?
Also, can anyone point to an example of a server->multiple client connection example using bluetooth with Android? I came across an Air Hockey example:
http://code.google.com/p/apps-for-android/source/browse/#svn%2Ftrunk%2FBTClickLinkCompete%2Fsrc%2Fnet%2Fclc%2Fbt
But this project is very glitchy on my test devices and the actual game won't display properly. Does anyone know if there is an example of BluetoothChat extended to handle multiple connections?
UPDATE:
In attempting to solve this issue, I believe I have successfully extended the official Android Bluetooth Chat example to work with a server connecting to multiple clients.
I've uploaded my modifications to github here.
One device acts as the server by selecting "Menu>Make discoverable". Each client then connects by selecting "Menu>Connect a device". I was successfully able to connect my Motorola Droid and HTC Eris as clients to my Samsung Galaxy Tab 10.1". Each message sent from a client displays only on the server. A message sent from the server displays on all clients.
This was a tedious process getting it to work at all. Connectivity with the HTC devices is sporadic, though. I've read elsewhere that bluetooth on HTC is buggy, so I'm chalking it up to that.
Hopefully someone else will find this example useful. If you have any questions, suggestions, or other feedback, please let me know.
I tested your code. As, you said connecting HTC as master was a problem. I made Samsung S3 as master and HTC as client. it worked. But i tried again with a Sony Ericsson phone. No other device could successfully act as master.
S3 has Blutooth version 4.0 other have earlier version. Do you think the problem is because of Bluetooth stack?
I need to use this concept in a project where the devices will be custom made. Trying to find out weather the problem is related to vendors ( HTC, Sony) or its related to bluetooth stack. and i don't know how to find out. This is not documented. :(
Has anyone faced this?