Unable to start 2 periodic advertisers on nrf54L15

[Gilles Boccon-Gibod]

Using the Zephyr HCI_UART sample, configured and built for an nrf54L15 DK, with version 3.2.1 of the SDK, I get an HCI error 7 (Memory Capacity Exceeded) when attempting to configure a second periodic advertiser.

Here's a partial log that shows the HCI command used and the error returned:

```

19:08:00.157 D bumble.host: ### CONTROLLER -> HOST: HCI_COMMAND_COMPLETE_EVENT:
num_hci_command_packets: 1
command_opcode: HCI_LE_SET_EXTENDED_ADVERTISING_DATA_COMMAND
return_parameters: HCI_SUCCESS
19:08:00.157 D bumble.host: ### HOST -> CONTROLLER: HCI_LE_SET_PERIODIC_ADVERTISING_PARAMETERS_COMMAND:
advertising_handle: 1
periodic_advertising_interval_min: 80
periodic_advertising_interval_max: 800
periodic_advertising_properties: 0
19:08:00.157 D bumble.host: ### CONTROLLER -> HOST: HCI_COMMAND_COMPLETE_EVENT:
num_hci_command_packets: 1
command_opcode: HCI_LE_SET_PERIODIC_ADVERTISING_PARAMETERS_COMMAND
return_parameters: HCI_MEMORY_CAPACITY_EXCEEDED_ERROR

```

Sending the `HCI_LE_SET_PERIODIC_ADVERTISING_PARAMETERS_COMMAND` command for the first advertising handle (handle 0x00) worked, but the second one (handle 0x01) fails.

Both advertisers have the same parameters. For both periodic advertisers, the periodic advertising data size is 42 bytes.

I wasn't able to find a KConfig or other config setting that would relate to this specific issue (like a maximum number of periodic advertisers, or a maximum data size specifically for periodic advertising)

[Kenneth]

Hello,

I am not aware of any specific limit, but I can ask internally. In the meantime you can check that you have configured more than 1 advertising, e.g. look at:
https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/samples/bluetooth/peripheral_with_multiple_identities/README.html#number_of_advertisers 

From the source documentation I can find \nrfxlib\softdevice_controller\include\sdc_hci_cmd_le.h :

* If the Advertising_Handle does not identify an advertising set that is already configured

 * for periodic advertising and the Controller is unable to support more periodic advertising

 * at present, the Controller shall return the error code Memory Capacity Exceeded (0x07).

Kenneth

[Gilles Boccon-Gibod]

Setting `CONFIG_BT_EXT_ADV_MAX_ADV_SET=2` does indeed fix the issue.

It is somewhat confusing, because I have `CONFIG_BT_CTLR_ADV_SET=3`, which is supposed to be the limit at the controller level, and indeed, the controller returns 3 when queried with `LE_READ_NUMBER_OF_SUPPORTED_ADVERTISING_SETS_COMMAND`, but somehow `CONFIG_BT_EXT_ADV_MAX_ADV_SET` applies a further restriction, which can't be queried with HCI commands (and that I assumed applied only to the host stack, not the controller).