NCS 3.1.0 vble connect error at bt_hci_cmd_send_sync()

[shai735]

I am using nrf54l15 with NCS v3.1.0 with the following error when i connect it(i worked in NCS v2.9.1 successfully):

Controller unresponsive, command opcode 0x2035 timeout with err -11 in bt_hci_cmd_send_sync() function;

some error log info:

for matching ncs 3.1.0 I change this code：

bt_hci_cmd_create（）  was  deprecated，

So, I modified the functionality implemented with bt_hci_cmd_create to the code shown in the above image. Now it compiles successfully, but when connecting to the device and trying to reset the transmit power, the errors mentioned earlier occur.

My solution is to place set_tx_power inside a k_work_init_delayable for initialization and call it upon connection, while also stopping advertising during the connection. With this approach, the device can now connect successfully.

  

MY BT configs:

CONFIG_BT=y

CONFIG_BT_GATT_CLIENT=y

CONFIG_BT_LOG_LEVEL_WRN=y

CONFIG_BT_USER_PHY_UPDATE=y

CONFIG_BT_CTLR_SDC_TX_PACKET_COUNT=10

CONFIG_BT_BUF_EVT_RX_COUNT=12

CONFIG_BT_BUF_ACL_TX_COUNT=10

CONFIG_BT_L2CAP_TX_MTU=247

CONFIG_BT_BUF_ACL_RX_SIZE=251

CONFIG_BT_BUF_ACL_TX_SIZE=251

CONFIG_BT_CTLR_DATA_LENGTH_MAX=251

CONFIG_BT_DATA_LEN_UPDATE=y

CONFIG_BT_USER_DATA_LEN_UPDATE=y

CONFIG_BT_CTLR_TX_PWR_DYNAMIC_CONTROL=y

I would like to ask whether there is a correct solution to the aforementioned connection issue, or if my current solution is acceptable. If it is, why does modifying it in this way fix the connection problem?

Thank you very much!

[Einar Thorsrud]

Hi,

You are right, usigng a workqueue is a sensible approach in this case. I do not see any problems with your approach. (For reference, here is a similar thread from last week discussing this).

[shai735]

THANKS ! However, I still have some doubts. In version 3.1.0, why is it necessary to stop adv when a connection is established, and why must the power setting be executed within a task? Both are indispensable; only with them can the connection work properly

[Einar Thorsrud]

Hi,

Regardign advertisign, it is generally not needed to stop advertising after a connection is established. If your device should only allow a single connection and you configure the stack to support a single connection, there cannot be any connectable advertising while in a connection (and advertising can only be reastarted once you ge tthe recycled callback for the connection.

Regarding API calls from callback, it is generally bad practice, and that is particularily the case for blocking/syncroneous calls like bt_hci_cmd_send_sync(). (This is not documented in detail though, and I will suggest internally that this is documented properly).

[shai735]

Thanks for your reply! I have another question: in NCS 3.1.0, when a connection is established, will it continue to use the tx power that was set during advertising, or do I need to reconfigure it after the connection? 

[Einar Thorsrud]

Hi,

The Tx power you set for the advertising is also used for the connection that results from that advertising (though it can subsequently be chnaged for the connection if needed).