Unable to connect to Samsung S21

[_jonas_]

Hello,

I have a problem with the bluetooth connection to a Samsung s21. It connects for like two seconds and then disconnects immediately. Then tries to establish a new connection.

The strange thing is: It works fine on all other phones (iOS and Android) even the s21 Ultra works fine.

I'm in contact with the Samsung support team, they looked into the bluetooth log of the phone and pointed out that the MCU is not responding to the read request of the phone.

Here Samsung's answer:

The development team has got back to us.

Remote device didn't respond to the mobile's read request after HCILE_Connection_Update_Complete.

Android changed the connection interval to 7.5ms during the service discovery process. This is a normal in Android.

Please check why your devices do not respond after HCI_LE_ Connection_Update_Complete.

 

I have not found any information to fix the read request handling. I'm using NSC 2.6.1.

Can someone help me? 

Thanks in advance

Jonas

[ovrebekk]

Hi Jonas

What kind of application are you running on the peripheral side? Is it based on one of the standard SDK samples?

Would you be able to capture a sniffer trace when the issue occurs, so we can look into it in more detail?

If you don't have a professional Bluetooth sniffer available it is possible to use the nRF Sniffer. 

Best regards
Torbjørn

[_jonas_]

Hello, thank you for your answer and sorry for the late reply.

I managed to fix the problem by using Zephyr's Link Layer library instead of the Nordic Softdevice.

Kind regards

Jonas

[ovrebekk]

Hi Jonas

I would not recommend using the Zephyr controller in a production design, as it doesn't have the necessary Bluetooth qualification needed to certify your product. 

If you are able to share a sniffer trace showing both the non working SoftDevice based implementation and the working one based on the Zephyr controller I can share it with the Bluetooth developers, and try to get to the bottom of the issue. 

Best regards
Torbjørn

[_jonas_]

Hi Torbjørn,

I'm quite happy with the Zephyr LL Controller since it also shrinks down the image size by a lot. I did some searching online but could not find any information on it not being qualified for certification. Can you give me some more insights into this. Maybe an article or a forum post? I found this Building a qualified BLE Controller with Zephyr OS 1.9++ which suggests the opposite does't it?

Anyway I will do the sniffing tomorrow and let you know about the results.

Jonas

[ovrebekk]

Hi Jonas

The link you point to is from 2017, and while it is true that a much older version of the Zephyr controller was qualified, the later versions are not. 

It is true that the documentation today doesn't properly state this limitation, and we are planning to improve this in a future update. The plan is to include a text like the one below: 

The SoftDevice Controller is the supported Bluetooth controller in the nRF Connect SDK. Application examples in the SDK use the SoftDevice Controller as the default controller, and it is the controller used for release testing of the SDK. The Bluetooth support includes:

• Implementation of new Bluetooth LE controller features.
• Valid qualification (QDID) for each SDK release.
• Support request can be addressed on Devzone (link)

The Zephyr Bluetooth LE Controller is a community supported Bluetooth controller which is part of the Zephyr Project. It is the default Bluetooth controller when using Zephyr RTOS stand-alone. It is possible to configure projects in nRF Connect SDK to use the Zephyr Controller, but Nordic Semiconductor do not intend to support this configuration for production.

Best regards
Torbjørn