Extended Advertiser Example Fails with HCI_MEMORY_CAPACITY_EXCEEDED_ERROR on nRF52840 dongle (Zephyr hci_usb)

[afiffahreza]

I am trying to run the run_extended_advertiser_2.py example from the Bumble framework using an nRF52840 Dongle flashed with the Zephyr hci_usb sample.

To enable Extended Advertising, I added the following configurations to the prj.conf:

CONFIG_BT_EXT_ADV=y
CONFIG_BT_EXT_ADV_MAX_ADV_SET=4
CONFIG_BT_CTLR_ADV_EXT=y
CONFIG_BT_CTLR_ADV_SET=4
CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=191

The logs confirm the controller is reporting support for 4 advertising sets and a max data length of 191 bytes, as expected:

num_supported_advertising_sets: 4
max_advertising_data_length: 191

However, the script fails when attempting to enable the second advertising set (handle 1), returning a HCI_MEMORY_CAPACITY_EXCEEDED_ERROR [0x7]. The first advertising set (handle 0) starts successfully.

Log Snippet Showing the Failure:

...
11:58:58.410 D bumble.host: ### HOST -> CONTROLLER: HCI_LE_SET_EXTENDED_ADVERTISING_ENABLE_COMMAND:
  enable:                             1
  advertising_handles[0]:             1
  durations[0]:                       0
  max_extended_advertising_events[0]: 0
11:58:58.416 D bumble.host: ### CONTROLLER -> HOST: HCI_COMMAND_COMPLETE_EVENT:
  num_hci_command_packets: 1
  command_opcode:          HCI_LE_SET_EXTENDED_ADVERTISING_ENABLE_COMMAND
  return_parameters:       HCI_MEMORY_CAPACITY_EXCEEDED_ERROR
11:58:58.418 W bumble.host: HCI_LE_SET_EXTENDED_ADVERTISING_ENABLE_COMMAND failed (HCI_MEMORY_CAPACITY_EXCEEDED_ERROR)
11:58:58.419 E bumble.host: !!! Exception while sending command: HCI_Error(hci/HCI_MEMORY_CAPACITY_EXCEEDED_ERROR [0x7])
...

My question is, what is the most likely cause of the HCI_MEMORY_CAPACITY_EXCEEDED_ERROR when enabling the second set? Is there an additional Zephyr config option required to increase the memory or resource pool for concurrent advertising, particularly on the nRF52840 platform?

Any guidance on which Zephyr configuration parameters to adjust to resolve this memory/capacity issue would be greatly appreciated!

[afiffahreza]

I flashed my nRF52840 dongle with the hci_uart sample instead with the same conf appended to prj.conf and used serial transport, and now the extended advertiser example works perfectly!