I am building an Android app in which I need to connect to an custom device over classic Bluetooth (preferably). My problem is SDK for that device is not created to facilitate the connection. Now I am stuck onto the part where I need to create a Socket which will be opened by the custom device which is acting as a server and other Android devices will act as clients and connect to it.
I am stuck at the part where we need to have identical UUIDs at both client and server for the socket connection to work. I am following the BleutoothChatApp as reference for this but I cannot always make sure that both my app and custom device will have identical UUIDs. Because I may or may not be able to hard code the UUID in custom device.
What can I do in such case.?
Also when I try to use BLE and search for services, I discover only one service which has no description or anything.
What can I do in such cases. What will be the best approach to create a connection to that device.?
You get multiple UUIDs for the same device because the devices offer multiple services. Base UUID for Bluetooth is "00000000-0000-1000-8000-00805F9B34FB".
If you find this UUID in a device, it means it supports Bluetooth Service. Use the UUID for connecting to the device.
Related
I'm trying to establish a connection between my PC running Ubuntu and my iPhone via Bluetooth automatically when it becomes available, after being manually paired beforehand. I've seen this to be possible with certain peripherals, mainly audio. For example, my phone will automatically connect to a Bluetooth speaker when it is turned on and Bluetooth is active on my phone; another example is my phone automatically connects to my car's radio system via Bluetooth when I turn the car on.
I'm not able to connect my phone to my PC without first initiating the connection from the smartphone's Bluetooth menu. I'm thinking that I could possibly write an application for the PC to attempt to connect to the device every few minutes or something, but it seems that the phone needs to be the device to initiate the connection.
The only information that I need for what I'm trying to do ultimately is that the devices can pair successfully. Essentially I'm trying to build a sort of proximity trigger between my phone and my PC without using Wi-Fi and GPS - I can't use these for some specific reasons.
Is there any way to make this happen?
Yes this should be doable as long as you use the Background Processing feature for iOS apps. In the example I'll give below, we'll have the PC be the peripheral and the phone be the central, but you can really have it working either way. You will need to do the following:-
First initial connection needs to be performed in the foreground (this is due to iOS's background limitations).
On the iOS side, you need an application that acts as a central that scans and connects to the remove device (check this example as a starting point).
Upon connection, you need to bond with the PC. Bonding is important as it will prevent you from having to do the pairing again in the future. However, pairing/bonding is managed by the iPhone's OS so you cannot write it in your application, so the workaround is to have an encrypted characteristic on the PC side that will force the iPhone to bond (this is covered later).
On the PC side, you need to have a BlueZ script that acts as a peripheral that is always advertising. You can do this using bluetoothctl (check the examples here and here).
Before you start advertising, you need to have a GATT server on the PC side (to do this, check this example).
When registering characteristics, ensure that one of them has the encrypt-read property (you can find a full list of the properties here).
Now when you attempt to read this characteristic from the iOS side, the two devices should bond (make sure that your PC is bondable which you can do this via these commands).
Once the devices are paired, your iOS app needs to be working in the background constantly scanning and attempting to connect to the same peripheral (have a look at this and this example).
You can find more useful information at the links below:-
Getting started with Bluetooth Low Energy
The Ultimate Guide to CoreBluetooth Development
How to manage Bluetooth devices on Linux using bluetoothctl
I am trying to create a custom device to connect to an app via BLE. The device can be discovered using nRF connect and other BLE scanners, but not with the app i'm trying to use. Any idea what the issue is? Could it be something with the UUID?
We've got a use case in which a BLE connection is used to do the basic configuration of an embedded device via an Android app (later also via an iPhone app). The embedded device runs Linux and thus uses BlueZ as Bluetooth stack.
Using the DBus-API of BlueZ, bonding is made possible by making the device pairable, discoverable, and activating advertising. After bonding the apps can access the GATT services and characteristics
(which require bonding to be read/written) on the embedded device.
After the setup is done the bonding of the device (running the app) that managed the setup process, is supposed to be removed. In order to do that we call RemoveDevice() of org.bluez.Adapter1.
The BlueZ documentation states the following
void RemoveDevice(object device)
This removes the remote device object at the given
path. It will remove also the pairing information.
Still the app is able to access the GATT characteristics afterwards.
If bluetoothctl is used to check the list of paired devices, the list is not containing that device anymore though. Before calling RemoveDevice() the bonded device was visible there.
If bluetootd is stopped and restarted the app is no longer able to read/write the GATT characteristics, but needs to re-bonded before doing so.
I can neither find any further information in the BlueZ documentation nor can I find anything about this topic searching anywhere else.
Is this intended behavior or is this a bug? Does "remove pairing information" also mean "remove bonding information"? If this is intended behavior, how do we properly terminate bonding with a device?
Should I use the BlueZ Management API instead of the BlueZ API? I'm not sure about this as multiple source state that the DBus-API is the way to go.
RemoveDevice() indeed removes the bonding information as well. So you have to disconnect first and then call RemoveDevice(). The next time you connect the bonding information will be gone.
However, note that if you only make use of encrypted characteristics, you can still connect and discover services. Only once you start reading/writing the encrypted characteristics will Bluez check if you are bonded.
I was wondering if there's any way that I can control BLE device pairing specific to my app running on mobile device?
I do not want to write my own bluetooth profile so that only my app can talk to the BLE device instead i want to standard profiles available in BLE device but when it's paired to my phone, only my app should be able to communicate to it and none of the other apps should be able to communicate.
No don't do that.
If you MUST then you should encrypt your data with a key only your app knows.
Bluetooth Low Energy is supposed to be open and free for all.
What is the purpose for you to block others? Preventing them to block your service?
Then use some pre-shared key to verify that it's your app in both sides and close the connection if it's not.
I'm currently looking for a way to list the services exposed by a remote bluetooth device and to enable them.
Normally I would be using the WindowsAPI-functions (or more likely one of the known wrappers) to list the services and to enable them by GUID (SetServiceEnable).
The problem is, that the device is exposing two Services with the same GUID!
Thus using the windowsAPI-functions only enables one of these services. The other service can't be enabled.
I thought perhaps WMI could do the trick, but I'm still new to WMI and couldn't find any
Windows itself is able to enable both, none or a specific service over the servicemenu.
UPDATE
The problem I want to solve is to be able to enable either the first or the second service. By now only the first service (which is usually the service I need), but I couldn't find a solution to enable the second service (except by using the Windows UI).
If both services are enabled I have two Commports in devicemanager (SPP).
Since I can't add comment/questions (don't have the privilege on stackoverflow yet). Here's my best take.
If I understand correctly, it's invalid to have the service available more than once in the service record, right? Can you right click on the device in Bluetooth Pairing UI and see if you see two services and that you can enable them through the Windows UI? And once you enable them do you see two PNP devnodes under that device in device manager (view by connection) with the corresponding opposite role of the two service you enabled? (I can't try this because I don't know of a device I have with two identical UUIDs.)
As you might already know, when you enable service on a remote device, you are not actually enabling the service on the remote device through the Windows Bluetooth API. What you are doing is telling the core bluetooth component in Windows to generate the corresponding opposite role of the service. (This is what BluetoothSetLocalServiceInfo does.) For example, if the remote device supports A2DP sink, by enabling that service the Bluetooth service on desktop would then register a A2DP source service for that device, which generates a PNP devnode for matching A2DP source drivers to install on that devnode. By disabling that service, the Bluetooth service would then unregister the A2DP source devnode and the PNP devnode would be removed (sort of like unplugging a USB device).
Depending on what profile you are seeing being duplicated, it might not make sense to have two instances of device objects and driver objects that matches on the same mac address of the remote device.
My answer (which is actually not answering your question) is to check if it's even valid for the two services to be enabled in that case on the desktop with the drivers on the desktop that you will be working with. For example, a bundle of A2DP plus HFP would require A2DP and HFP to synchronize certain behavior, such as AVDTP suspend. Depending on the implementation and the drivers, they might not be expecting there are two instances of A2DP driver installed, hence causing the unexpected state of the local drivers.