bt_ascs: Failed to register ISO server -134

RE: bt_ascs: Failed to register ISO server -134

Maria Gilje — Wed, 09 Jul 2025 12:22:04 GMT

Hi,

[quote user="Rafael Vidal"]2) I have also added symbol "CONFIG_BT_LL_SW_SPLIT=y" on my /sybuild/ipc_radio/ipc_radio.conf[/quote]

This will select the Zephyr controller, so this should not be included when you mean to use the SoftDevice Controller. See the Kconfig documentation for the symbol: https://docs.nordicsemi.com/bundle/ncs-latest/page/kconfig/index.html#CONFIG_BT_LL_SW_SPLIT.

The other descriptions of what you have done are good.

[quote user="Rafael Vidal"]1) Where exactly should those multicore radio settings live? In the /sysbuild/ipc_radio/prj.conf or the CPUAPP prj.conf?[/quote]

There are a few options for this. In cases where you have multiple Kconfig fragments (or dts overlays) for one or several images, it is recommended to have all the configurations in a subfolder in the sysbuild directory. If you only have one Kconfig fragment for each image, placing the fragment directly in the sysbuild directory is fine. More information on this can be found here.

[quote user="Rafael Vidal"]
2) How can I verify that the net-core actually ran the HCI-IPC build (and not the default Zephyr Controller)? Is there a specific log or HCI version query I should look for?[/quote]

I used the VS Code extension and verified which image was running on the network core and which Kconfig fragments were active. This can be verified before running the sample on hardware.

[quote user="Rafael Vidal"]3) Is my sysbuild.cmake approach correct, or is there a simpler way to force the net-core image override?[/quote]

It looks mostly alright.

Just make sure that sysbuild/ipc_radio/prj.conf has all the Kconfig symbols needed. When specifying a CONF_FILE, this file will be the base configuration file and other fragments will be added to it if found by the build system. You could also specify EXTRA_CONF_FILE instead. This will add sysbuild/ipc_radio/prj.conf to the other Kconfig fragments (like the prj.conf in the ipc_radio application directory).

[quote user="Rafael Vidal"] 4) Any other Kconfig symbols or steps I’m missing so that the ASCS ISO server can register successfully?[/quote]

I'm not sure. If my comments from this reply is not helpful, I can clean up the sample I used to reproduce and fix on my end so you have a reference to use for comparison on your end.

Best regards,

Maria

RE: bt_ascs: Failed to register ISO server -134

Rafael Vidal — Mon, 07 Jul 2025 18:17:24 GMT

Hi Maria,

Thanks again for your suggestions. I’ve made all the changes you recommended, but I’m still seeing:

[00:00:00.283,447] <err> bt_ascs: Failed to register ISO server -134
Failed to create adv set (err -5)

I suspect the network-core image still isn’t running the HCI-IPC “radio” build, so the ISO channels never come up. Here’s what I’ve done so far:

1) I have created a sysbuild.cmake file, though there is none on the unicast example.

2) I have also added symbol "CONFIG_BT_LL_SW_SPLIT=y" on my /sybuild/ipc_radio/ipc_radio.conf

3) Compiler was requiring a prj.conf on "/sysbuild/ipc_radio/" folder, so I renamed the original ipc_radio.conf.

/sysbuild/ipc_radio/prj.conf
Added the minimal radio config you suggested, plus our multicore controller options:

CONFIG_BT_ISO_PERIPHERAL=y
# less than 16 at least, but tested with 4
CONFIG_BT_MAX_CONN=4
CONFIG_CLOCK_CONTROL=y
CONFIG_CLOCK_CONTROL_NRF=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_BT=y
CONFIG_BT_EXT_ADV=y
CONFIG_BT_LL_SW_SPLIT=y

Despite all that, after west flash I only see the CPUAPP logging (“Bluetooth initialized”), and the net-core still reports the standard controller firmware (no HCI-IPC). The ASCS –134 error persists.

Could you please help me confirm:

1) Where exactly should those multicore radio settings live? In the /sysbuild/ipc_radio/prj.conf or the CPUAPP prj.conf?

2) How can I verify that the net-core actually ran the HCI-IPC build (and not the default Zephyr Controller)? Is there a specific log or HCI version query I should look for?

3) Is my sysbuild.cmake approach correct, or is there a simpler way to force the net-core image override?

4) Any other Kconfig symbols or steps I’m missing so that the ASCS ISO server can register successfully?

Best regards,

# SPDX-License-Identifier: Apache-2.0
# sysbuild.cmake — solo net-core “ipc_radio” + CPUAPP

# Si en Kconfig.sysbuild habilitamos NET_CORE_IMAGE_IPC_RADIO, añadimos el net-core:
if (SB_CONFIG_NET_CORE_IMAGE_IPC_RADIO)

    ExternalZephyrProject_Add(
        APPLICATION  ipc_radio
        SOURCE_DIR   ${ZEPHYR_BASE}/../nrf/applications/ipc_radio
        BOARD        ${SB_CONFIG_NET_CORE_BOARD}

        # Le decimos que use nuestro prj.conf para ese dominio CPUNET:
        CONF_FILE    ${CMAKE_CURRENT_LIST_DIR}/sysbuild/ipc_radio/prj.conf
    )
endif()

# No necesitamos orquestar imágenes de simulador, ni hci_ipc en Zephyr samples.

RE: bt_ascs: Failed to register ISO server -134

Maria Gilje — Wed, 02 Jul 2025 12:09:52 GMT

Hi,

I reproduced the error with the BAP unicast server sample and the default main.c, and I also noticed that the default network core image was HCI IPC with the Zephyr Controller. I was able to resolve the error with these additions:

Added a sysbuild.conf with SB_CONFIG_NETCORE_IPC_RADIO_BT_HCI_IPC=y

Ensured that the IPC radio application was chosen by default by replacing the net core default image in Kconfig.sysbuild:

# config NET_CORE_IMAGE_HCI_IPC
# 	bool "HCI IPC image on network core"
# 	default y
# 	depends on NET_CORE_BOARD != "" 

config NRF_DEFAULT_IPC_RADIO 
	default y
	depends on NET_CORE_BOARD != ""

Added two Kconfigs symbols to sysbuild/ipc_radio.conf

CONFIG_BT_ISO_PERIPHERAL=y
CONFIG_BT_MAX_CONN=4 # less than 16 at least, but tested with 4

I was not able to get any logging with your main.c, but let me know if my suggested modifications above causes any issues, and I'll try again to run your main.c.

Best regards,

Maria

RE: bt_ascs: Failed to register ISO server -134

Maria Gilje — Mon, 30 Jun 2025 13:59:15 GMT

Thank you for sharing your modified sample. I have reproduced the error and I'm actively looking for an explanation and solution.

Best regards,

Maria

RE: bt_ascs: Failed to register ISO server -134

Rafael Vidal — Thu, 26 Jun 2025 21:37:04 GMT

Hi Maria,

thanks for the quick reply; I attach the modified unicast example file. We have tried to simplify as much as possible the code. On the main, we just call ble_audio_init(); and no, we have not been able to run the unicast server. I think the problem is related to configuration.

devzone.nordicsemi.com/.../5826.BLE_2D00_audio_2D00_connection.c

RE: bt_ascs: Failed to register ISO server -134

Maria Gilje — Thu, 26 Jun 2025 14:10:40 GMT

Hi Rafael,

I will look into this, my first step will be to reproduce the error. Do you have and overview of the modifications made to the Unicast Audio Server sample?

Have you been able to make an unmodified sample run successfully?

Best regards,

Maria