Connect uart_peripheral with Windows 11

RE: Connect uart_peripheral with Windows 11

Bernat — Fri, 25 Apr 2025 16:52:46 GMT

Hi Neil!

Could you found the root cause of the problem? I'm facing the same problem and it's quite frustrating...

I also use Bluetooth LE Explorer, but only to pair the BLE device to the Windows 11. Once paired, I forget about this software and use C# with .NET 6 Core to communicate with the devices.

I've developed several projects, involving heart rate monitors (like the Polar, or the Coospo optical one), or even using the ESP32 as a BLE module and implementing the services and characteristics by hand. They all pair and connect fine to my PC. So, for the first time ever, I'm having trouble with a module from EByte (E104-BT5005A) which uses a nRF52805. If I try enough times, I get the Bluetooth LE Explorer to connect 1 out of about 20 times, but I still could never paired to it.

Is it a problem from the nRF stack? It seems clear it's not a problem from Bluetooth LE Explorer, since I could pair all kind of BLE devices UNTIL now...

Thank you!

RE: Connect uart_peripheral with Windows 11

Neil Benn — Wed, 22 Jan 2025 20:07:48 GMT

Hello,

This would make sense and/or the windows pairing process trying to use the system bluetooth was not complete- however I've done too much to determine which it is. I'll create the use cases to determine which it was and go from there as I'll obviously not want this to happen in the field as I'm making a B2C product. For now I'll close this ticket and thanks very much for your help.

Cheers,

Neil

RE: Connect uart_peripheral with Windows 11

Einar Thorsrud — Wed, 22 Jan 2025 11:56:24 GMT

Hi Neil,

That seems to match the trace (though I don't see the context of the packets), the nRF recjects encryption probably probalby as it does not have the bonding data, and for that reason, the central disconnecs. This is expected behaviour.

[quote user="Neil Benn"]Though I still need to understand what went wrong in the first place.[/quote]

Do you mean why the PC has a bond and the nRF does not? A typical reason is that the nRF was re-programmed, and in the process, the flash was erased, including the bond(s). Could that be what happened?

RE: Connect uart_peripheral with Windows 11

Neil Benn — Tue, 21 Jan 2025 12:31:42 GMT

Hello,

Thanks for your response, to note - I'm not using BLE Explorer; this was just one of the examples of test applications which cannot interact with the nrf52dk including the windows native system (just to pair and connect) and a couple of python-based applications. I'm also not looking for native support in Windows but not sure how native support for a simple example like this would work anyways as it has no functionality but to receive a few bytes and dump them on the log. However I do want to write a piece of code which can communicate to the uart_peripheral running on a nordic nrf52dk. The eventual aim is to have a windows program that can communicate to the device embedded in a product based around the nordic system.

I just wanted to make the above clear as the BLE Explorer application is confusing matters, so moving on:

I've use the BLE sniffer as in the instructions and the following packets are detected:

1885	32.016	Intel_4c:5d:23	LE 1M	LE LL	34	151µs				0	CONNECT_IND
1886	32.032	Central_0x3316f157	LE 1M	LE LL	9	15343µs	0	0	False	0	Control Opcode: LL_FEATURE_REQ
1887	32.032	Peripheral_0x3316f157	LE 1M	LE LL	0	150µs	0	1	False	0	Empty PDU
1888	32.077	Central_0x3316f157	LE 1M	LE LL	0	44619µs	1	1	False	1	Empty PDU
1889	32.077	Peripheral_0x3316f157	LE 1M	LE LL	9	150µs	1	0	False	1	Control Opcode: LL_FEATURE_RSP
1890	32.122	Central_0x3316f157	LE 1M	LE LL	23	44619µs	0	0	False	2	Control Opcode: LL_ENC_REQ
1891	32.122	Peripheral_0x3316f157	LE 1M	LE LL	0	150µs	0	1	False	2	Empty PDU
1892	32.167	Central_0x3316f157	LE 1M	LE LL	0	44507µs	1	1	False	3	Empty PDU
1893	32.167	Peripheral_0x3316f157	LE 1M	LE LL	13	149µs	1	0	False	3	Control Opcode: LL_ENC_RSP
1894	32.212	Central_0x3316f157	LE 1M	LE LL	0	44588µs	0	0	False	4	Empty PDU
1895	32.212	Peripheral_0x3316f157	LE 1M	LE LL	0	149µs	0	1	False	4	Empty PDU
1896	32.257	Central_0x3316f157	LE 1M	LE LL	0	44691µs	1	1	False	5	Empty PDU
1897	32.257	Peripheral_0x3316f157	LE 1M	LE LL	3	150µs	1	0	False	5	Control Opcode: LL_REJECT_EXT_IND
1898	32.302	Central_0x3316f157	LE 1M	LE LL	9	44667µs	0	0	True	6	Control Opcode: LL_LENGTH_REQ
1899	32.302	Peripheral_0x3316f157	LE 1M	LE LL	0	150µs	0	1	False	6	Empty PDU
1900	32.302	Central_0x3316f157	LE 1M	LE LL	2	150µs	1	1	False	6	Control Opcode: LL_TERMINATE_IND
1901	32.347	Central_0x3316f157	LE 1M	LE LL	2	44373µs	1	1	False	7	Control Opcode: LL_TERMINATE_IND
1902	32.347	Peripheral_0x3316f157	LE 1M	LE LL	9	150µs	1	0	False	7	Control Opcode: LL_PERIPHERAL_FEATURE_REQ

The last communication is regarding encryption and the central sends to the peripheral LL_LENGTH_REQ which times out I thing; then the link is disconnected. Can you please advise as to what the possible cause could be?

UPDATE - I've run the same code from a linux box and the difference is that the encryption request opcode isn't sent from the linux box; the length_req opcode is still ignored by the peripheral but then we launch straight into feature discovery.

UPDATE 2 - there was an old paring left over from the bluetooth system attempt to previously pair which the peripheral. If this is removed the windows python code now works. Though I still need to understand what went wrong in the first place.

Cheers,

Neil

RE: Connect uart_peripheral with Windows 11

Einar Thorsrud — Tue, 21 Jan 2025 10:25:11 GMT

Hi Neil,

[quote user="Neil Benn"]This seems like a fairly simple example and windows is quite common - are there any use cases where uart_peripheral connected to from windows is actually working?[/quote]

There is no native support for the Nordic UART service (NUS) which is used in the peripheral_Uart sample on Windows, as this is a custom service designed by Nordic. So to use it with Windws you either need some form of test application (for which BLE explorer is a simple variant of) or write your own PC side application. From what I know the BLE explorer application is not much used and we do not have much experience with it nor knowledge of its implemnetation or limitations.

[quote user="Neil Benn"]Is there any way we can determine what the nrf52dk is actually sending to the windows computer?[/quote]

The normal way to invesitgate such things is with a BLE sniffer. Even if you don't have a dedicated BLE sniffer, you can use the nRF Sniffer as long as you have an extra nRF52 series DK or dongle.

Einar

RE: Connect uart_peripheral with Windows 11

Neil Benn — Mon, 20 Jan 2025 14:23:50 GMT

Hello,

Thanks for that - I've tested with multiple python packages and BLE explorer - they all do the same thing. I have tried nrfConnect for Desktop with the nrf52840 Dongle and that does indeed connect to teh uaryt_peripheral running on the nrf52dk board.

However; I need to write code to test the NRF52dk package and I can't do that with nrf Connect for Desktop BLE - all I can do is send a few bytes back and forth.

This seems like a fairly simple example and windows is quite common - are there any use cases where uart_peripheral connected to from windows is actually working? Is there any way we can determine what the nrf52dk is actually sending to the windows computer?

Cheers,

Neil

RE: Connect uart_peripheral with Windows 11

Einar Thorsrud — Mon, 20 Jan 2025 14:09:39 GMT

Hi Neil,

The disconnect reason indicate that the peer (PC) disconnected for some reason, but does not tell us why. You will need to look more on the side that disconnected (PC) to understand more about that. I don't know the details of how Bluetooth LE Explorer work and why it would choose to disconnect in some cases. Is it possible to get more logging from it? Other than that, I suggest asking Microsoft support for details on Bluetooth LE Explorer as it is their product. As an alternative if you need a BLE tool for testing from a computer you could consider nRF Connect for Desktop BLE.

Einar