How works the Broadcast Source Device with Broadcast Audio Assistant and non-nordic headset compatible Auracast.

[selim.pousse]

nrf Toolchain: 2.7.0
nrf Connect SDK : 2.7.0
Gateway: nrF5340 Audio DK
Headset: Earbud 'MOMENTUM TW 4' (Sennheiser)

I try to run and test this following application "Broadcast Source"  into the nrF5340 Audio DK (as role gateway) which should interact with auracast earbuds 'MOMENTUM TW 4' (as role headset).

As far as I understand , we need an intermediate "Broadcast Audio Assistant Device" which can be a smartphone (using nrf Connect Mobile ?), a PC, or a nrf-DK with LE audio support:

Use Case 1: Try to use the nrF5340 Audio DK (running "Broadcast Source" app) as gateway, my smartphone as Broadcast Audio Assistant Device and my auracast eardbud 'MOMENTUM TW 4' as headset.
The broadcast service of nrF5340 is published and detected by the nrf Connect mobile app. but my smartphone doesn't support the LE audio support. Is it necessary for the smartphone to support the LE Audio to manage the nrF5340 broadcast service and be able to select the advertisement or the channel wished to be listened ?

Use Case 2: Try to use a 1st nrF5340 Audio DK as gateway, a second nrF5340 Audio DK as Broadcast Audio Assistant, and auracast Headset 'MOMENTUM TW 4'
"Broadcast Audio Assistant" provided by Zephyr Project seems not working into the 2nd nrF5340-Audio-DK which play the role of the Assistant. According the doc, only nrf52840dk is supported.

*** Booting nRF Connect SDK v2.7.0-5cb85570ca43 ***
*** Using Zephyr OS v3.6.99-100befc70c74 ***
[00:00:00.415,588] <inf> bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.415,649] <inf> bt_hci_core: HW Variant: nRF53x (0x0003)
[00:00:00.415,649] <inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 214.51162 Build 1926957230
[00:00:00.417,419] <inf> bt_hci_core: Identity: C6:95:06:0E:89:94 (random)
[00:00:00.417,449] <inf> bt_hci_core: HCI: version 5.4 (0x0d) revision 0x21fb, manufacturer 0x0059
[00:00:00.417,480] <inf> bt_hci_core: LMP: version 5.4 (0x0d) subver 0x21fb
Bluetooth initialized
[00:00:00.419,738] <wrn> bt_hci_core: opcode 0x2041 status 0x01
Scanning failed to start (err -5)

First, what I try to achieve makes sense ? if yes, can you help me to understand this issue of running an Broadcast Audio Assistant into a nrF5340-Audio-DK.

Thank in advance for your answers and Best Regards.

[Amanda Hsieh]

Closed as duplicated  Unicast Client App interacting with non-nordic Headset   

[selim.pousse]

Thank a lot for your help, adjusting the code of broadcast_audio_assistant app did help. here the resulting logs:

[00:00:25.317,535] <inf> bt_id: NRPA: 32:98:84:94:64:98
Scanning for Broadcast Sink successfully started
Broadcast Sink Found:
  BT Name:        
'MOMENTUM' not found in names

Broadcast Sink Found:
  BT Name:        
'MOMENTUM' not found in names

Broadcast Sink Found:
  BT Name:        MOMENTUM TW 4
Match found for 'MOMENTUM'
Connecting to Broadcast Sink: MOMENTUM TW 4
Connected: 47:6B:23:F0:CF:EB (random)
[00:00:27.807,678] <inf> bt_smp: SC LTK: 0xd9c530b7db3baf6348ecb61780503ae4 (No bonding)
Security level changed: 2
BASS discover done with 1 recv states
[00:00:28.019,775] <inf> bt_id: NRPA: 0D:70:97:2C:3B:42
Scanning for Broadcast Source successfully started
Broadcast Source Found:
  BT Name:        MOMENTUM TW 4
  Broadcast Name: NRF5340_BROADCASTER
  Broadcast ID:   0x96a0b5

Match found for 'NRF5340_BROADCASTER'
Selecting Broadcast ID: 0x96a0b5
Attempting to PA sync to the broadcaster with id 0x96A0B5
Scan stopped, attempting to PA sync to the broadcaster with id 0x96A0B5
[00:00:28.107,299] <inf> bt_id: NRPA: 1B:47:71:82:6B:30
Waiting for PA synced
Broadcast Source Found:
  BT Name:        MOMENTUM TW 4
  Broadcast Name: NRF5340_BROADCASTER
  Broadcast ID:   0x96a0b5

Match found for 'NRF5340_BROADCASTER'
bt_le_scan_stop failed with -120
Selecting Broadcast ID: 0x96a0b5
Attempting to PA sync to the broadcaster with id 0x96A0B5
Broadcast Source Found:
  BT Name:        MOMENTUM TW 4
  Broadcast Name: NRF5340_BROADCASTER
  Broadcast ID:   0x96a0b5

Match found for 'NRF5340_BROADCASTER'
bt_le_scan_stop failed with -120
Selecting Broadcast ID: 0x96a0b5
Attempting to PA sync to the broadcaster with id 0x96A0B5
PA sync 0x20002324 synced for broadcast sink with broadcast ID 0x96A0B5
BASS add source successful

I was able to hear the music broadcast into the earbuds at the first attempt   (but with a poor sound quality).
But unfortunately, afterwards from the 2nd attempt, I was not able anymore to hear anything and to reproduce the same result...

Additional Notes:
Now, I was able to listen multiple times to the broadcast audio stream but still with very poor sound quality
How I can configure, control or improve the sound quality from the broadcast source app ?

Best Regards.

[Amanda Hsieh]

Hi, 

This is great news!

There could be a chance that the ACL connection packets between earbuds and BA(broadcast assistant) are collided with ISO packets from broadcaster.
Please follow the dev academy for setting the connection interval to 40ms or 45ms or a trial, or make the BA be able to handle the connection parameter update request from peripheral
https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-3-bluetooth-le-connections/topic/blefund-lesson-3-exercise-2/

We could also add 
CONFIG_BLE_ACL_PER_ADV_INT_MIN=0x50  
CONFIG_BLE_ACL_PER_ADV_INT_MAX=0x50 
CONFIG_BT_AUDIO_RETRANSMITS=4

This will make PER-ADV interval shorter, when should harder to make broadcast sink out of sink from broadcaster
And the last one will make the retransmission times more. 

-Amanda H.