nRF5340 LE Audio: BIS switching

RE: nRF5340 LE Audio: BIS switching

gocchan — Fri, 02 Dec 2022 01:13:13 GMT

Hi,

We have confirmed that BIS reception can be stopped and resynchronized by using bis_headset_cleanup() and bt_audio_broadcast_sink_scan_start().

And by using the id available with the callback, it seems that we can choose which gateway to receive next.

Resynchronization takes 2-3 seconds. I wish it was a bit more seamless, but I got it to work the way I wanted it to.

Regards,

Gotoda

RE: nRF5340 LE Audio: BIS switching

Maria Gilje — Tue, 29 Nov 2022 16:45:32 GMT

Hello Gotoda,

Sorry about the delay.

I will look into this shortly.

Regards,
Maria

RE: nRF5340 LE Audio: BIS switching

gocchan — Fri, 18 Nov 2022 06:32:53 GMT

Hello,

I implemented it as follows.

First, I increased the number of elements of the broadcast_sinks[] array defined in broadcast_sink.c to 2 to store 2 pieces of broadcast information. However, even with two gateways in close proximity, only one piece of information was stored.

#define HOSI_BT_AUDIO_BROADCAST_SNK_COUNT 2

static struct bt_audio_iso broadcast_sink_iso
	[HOSI_BT_AUDIO_BROADCAST_SNK_COUNT][BROADCAST_SNK_STREAM_CNT];
static struct bt_audio_ep broadcast_sink_eps
	[HOSI_BT_AUDIO_BROADCAST_SNK_COUNT][BROADCAST_SNK_STREAM_CNT];
static struct bt_audio_broadcast_sink broadcast_sinks[HOSI_BT_AUDIO_BROADCAST_SNK_COUNT];

Next, thinking that the scan to find other gateways had stopped when it synchronized with the first gateway, I called bt_audio_broadcast_sink_scan_start() at the end of the sync_broadcast_pa() function in broadcast_sink.c. However, an error code of -120 is returned.

static void sync_broadcast_pa(const struct bt_le_scan_recv_info *info,
			      uint32_t broadcast_id)
{
	struct bt_audio_broadcast_sink_cb *listener;
	struct bt_le_per_adv_sync_param param;
	struct bt_audio_broadcast_sink *sink;
	static bool pa_cb_registered;
	int err;

	if (!pa_cb_registered) {
		static struct bt_le_per_adv_sync_cb cb = {
			.synced = pa_synced,
			.recv = pa_recv,
			.term = pa_term,
			.biginfo = biginfo_recv
		};

		bt_le_per_adv_sync_cb_register(&cb);

		pa_cb_registered = true;
	}

	sink = broadcast_sink_free_get();
	/* Should never happen as we check for free entry before
	 * scanning
	 */
	__ASSERT(sink != NULL, "sink is NULL");

	bt_addr_le_copy(&param.addr, info->addr);
	param.options = 0;
	param.sid = info->sid;
	param.skip = PA_SYNC_SKIP;
	param.timeout = interval_to_sync_timeout(info->interval);
	err = bt_le_per_adv_sync_create(&param, &sink->pa_sync);
	if (err != 0) {
		BT_ERR("Could not sync to PA: %d", err);
		err = bt_le_scan_stop();
		if (err != 0 && err != -EALREADY) {
			BT_ERR("Could not stop scan: %d", err);
		}

		SYS_SLIST_FOR_EACH_CONTAINER(&sink_cbs, listener, _node) {
			if (listener->scan_term != NULL) {
				listener->scan_term(err);
			}
		}
	} else {
		sink->syncing = true;
		sink->pa_interval = info->interval;
		sink->broadcast_id = broadcast_id;
#if 1 /* Added. */
		if(bt_audio_broadcast_get_array_size() < ARRAY_SIZE(broadcast_sinks))
		{
			err = bt_audio_broadcast_sink_scan_start(BT_LE_SCAN_PASSIVE);
			if(err)
			{
				BT_ERR("bt_audio_broadcast_sink_scan_start(): %d", err);
			}
		}
#endif
	}
}

Is it possible to play broadcast signals from one gateway while receiving broadcast signals from another gateway?

Regards,

Gotoda

RE: nRF5340 LE Audio: BIS switching

Maria Gilje — Fri, 04 Nov 2022 06:53:18 GMT

Hi,

[quote user="gocchan"]Thank you, I'll refer to the function and the thread.[/quote]

Great!

[quote user="gocchan"]Is there a function for establishing BIS?[/quote]

You can find all Bluetooth related code relating to BIS in the files le_audio_bis_gateway.c and le_audio_bis_headset.c from the nRF5340 Audio application.

Kind Regards,
Maria

RE: nRF5340 LE Audio: BIS switching

gocchan — Wed, 02 Nov 2022 01:53:56 GMT

Hi,

Thank you, I'll refer to the function and the thread.

Is there a function for establishing BIS?

Regards,

Gotoda

RE: nRF5340 LE Audio: BIS switching

Maria Gilje — Fri, 28 Oct 2022 14:03:19 GMT

Hi,

bt_audio_broadcast_sink_scan_start() may help to scan for available gateways.

You can also add the gateway you want to connect to to a whitelist. This thread may be of some help here.

I am happy to help more and maybe test some configurations after the weekend.

Kind Regards,
Maria

RE: nRF5340 LE Audio: BIS switching

Maria Gilje — Thu, 27 Oct 2022 14:03:10 GMT

Hello again,

I have not found an existing API for gateway switching, but I will search some more.

Thank you for your patience.

Kind Regards,
Maria

RE: nRF5340 LE Audio: BIS switching

Maria Gilje — Fri, 21 Oct 2022 06:09:18 GMT

Hello Gotoda,

This should be possible, but I need some more time to find out if there is an existing API for gateway switching.

Thank you for your patience.

Kind Regards,
Maria