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Hi,
In my UWP Windows 10 App, I am using Window.Devices.Bluetooth to scan and connect to in-house Bluetooth Low Energy devices. Below is the code sample used for connecting (The mac addresses are known for in-house devices)
The test application using following two APIs:
using Windows.Devices.Bluetooth;
using Windows.Devices.Bluetooth.GenericAttributeProfile;
var bleDevice = BluetoothLEDevice.FromBluetoothAddressAsync
var services = bleDevice.GetGattServicesAsync
With multiple devices advertising, the API GetGattServicesAsync works fine for the first device but return 'Unreachable' status when connection is attempted while first device is still connected. We see same behavior for either of the devices connected first.
Similar functionality was working fine in the past but isn't working with recent version of windows and SDK (Windows 10 21H1, SDK target 19041, SDK min 17134).
Am I missing some configuration or this functionality isn't supported anymore. I have attached the source code file of a minimal example (changed extension to txt to allow the attachment)
Thanks
It turned out to be issue with BT's driver on lenovo P52 laptop. The issue initially resolved by using external dongle instead of internal BT. And after recent windows update to Intel Wireless Bluetooth driver v22.50.0.4, the multiple connections are working again with internet BT as well.
The good news is that what you're doing is intended to work, and that we don't know of any bugs in the Bluetooth stack that would fail. Connecting to multiple devices is definitely supported -- indeed, as my Bluetooth dev lead points out, if you've got a Bluetooth mouse and keyboard, that's two connections right there. We also have extensive tests (both internal and with partners) to ensure that multiple connections should work.
We have a Bluetooth Virtual Sniffer that might help you track down the problem:
We also have instructions on taking Bluetooth traces for a more detailed investigation.
Peter Smith
PM, Windows Bluetooth team
I have created a wireshark log with Bluetooth Virtual Sniffer. The log is available here
https://drive.google.com/open?id=1T22f69tkHScrmTi9oqW7V-16n_1mkEcL
The connection to first device is initiated at time 6.23 seconds which goes well and PC does the service discovery. And then at time 11.43 second, second connection is initiated and after 7-8 seconds, Host send the cancel connection request. And when I check in the device FW, the connection callback is never received for the 2nd device.
Is there anything else we can check further?
EDIT: I also created a log with Windows Performane Recorder
https://drive.google.com/file/d/1E1NfJvID2JfefbeEOmQyBgEX2mH3jWOn/view?usp=sharing
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I implemented an application to connect multiple sensors, Yes it is possible to connect several devices concurrently, at least i tested 6 devices. Using Bluetooth 5.1(LMP 10) and NRF52x module the maximum speed is 700K avg. but after fixing maximum throughput problem I faced with another problem,
When I connect first device it works with maximum speed, but it's very strange when i connect second device without any sending packet, first device speed goes down , and in multiple device test, bandwidth distribution is not equal for each device as you see in the first photo here. I tested a lot of configuration and solutions but, I guess the reason should be windows API or driver.
Why second device effects speed of the first one without sending data?
If you had any idea please let me know
Single device packet send log in slave side
After connecting second device even without sending packet! speed fall's down
Windows 10 SDK doesn't have any capability of changing and even reading connection parameter(Issues Method not found error for any usage of the function and related object ), I read that you put this function in latest version is working only in Windows 11... I'm always thinking why? ... it should be simple to pass connection parameter to app but Microsoft only add this to Windows 11 version ... why? :))