Bluetooth Advertising Interruption Issue with BlueZ Versions Above 5.55 on nRF52833

[Doris.chen]

We are currently using a Linux system and controlling HCI_UART firmware through BlueZ.

The problem we are encountering is that using BlueZ V5.55 allows normal Bluetooth advertising and connection with mobile phones. However, when using higher versions like 5.64 and 5.66, we experience interruptions in advertising.

Has anyone encountered similar issues? Do we need to adopt a higher version of NCS?

Or is there any modification needed in the firmware? Currently, we are using the original code provided by NCS.

Current information is as follows:

Board: nRF52833

NCS version: V2.5.0

[Amanda Hsieh]

Hi, 

It is worth trying to update your NCS version if there are any specific compatibility issues between the BlueZ version and the NCS version you are using. The latest NCS is v2.7.0. 

Regards,
Amanda H.

[Doris.chen]

Hi Amanda,

Is it possible that your HCI_UART code is subject to modifications at any time? From my previous understanding, the HCI_UART code should be fixed. However, I am not very familiar with the HCI_UART firmware, so I am not entirely sure.

Additionally, I came across this article on the forum. Could it be related to this issue?
NRF5340 HCI_USB & HCI_UART Stop Scanning 

I need a definite answer because this is for a verified product. Currently, with the same firmware, using BlueZ V5.55 works fine, but versions above V5.55 encounter this issue. This affects the program's workflow.

[Amanda Hsieh]

Hi,

Thanks for helping clarify the issue. I have reported to the team. 

We are currently understaffed due to the summer vacation period, so delayed replies must be expected. I am sorry about any inconvenience this might cause. 

-Amanda H.

[Doris.chen]

Hi Amanda,

Thank you for the update and support. However, the progress of this project is quite urgent, and we really need to receive relevant information as soon as possible. We would greatly appreciate it if you could expedite the processing.

Thank you for your understanding and assistance!

Best regards,

Doris

[Amanda Hsieh]

(updated)

Hi,

Are you using Zephyr Controller or SDC in NCS v2.7.0? 

What baud rate the hci_uart is built for?

I am noticing UART stall on large HCI events generated when using 1Mbps UART. Using 115200 bps, do not see such behavior.

-Amanda H.

[Doris.chen]

Hi Amanda,

I am not sure which controller I am using, but the sample code comes from v2.7.0\zephyr\samples\bluetooth\hci_uart. The baud rate I am using is 1 Mbps.

However, I believe the issue is not related to the baud rate. Based on the command and log messages in Linux, it seems that the command information is not recognized.

To clarify:

1. The issue does not occur in BlueZ 5.55.
2. The "advertise on" command is listed in the command list.

We are currently investigating the root cause, but if you have any experience or insights that could help, it would be greatly appreciated.

Best Regards,

Doris

[Amanda Hsieh]

(updated)

Hi,

Doris.chen said:

I am not sure which controller I am using, but the sample code comes from v2.7.0\zephyr\samples\bluetooth\hci_uart

The default setting is the Softdevice controller. Could you test with the Zephyr Controller? Set the CONFIG_BT_LL_SW_SPLIT=y in your configuration. This can be done in the prj.conf file of your application.

From the team:

This failure is different from the baud rate issue I have seen. Here with SDC, it thinks the Controller is a BR/EDR+LE Controller and hence requests HCI Read Local Name command!…

Please provide a full btmon trace, i.e. btmon started before btattach . I need the HCI commands like, HCI Read Supported commands, Features, etc.

-Amanda H.