RE: NRF52840: NCS 2.5.0 -> NCS 2.7.0 BLE advertising stops on disconnect

sheldon_b — Wed, 28 Aug 2024 14:14:15 GMT

I decided to set CONFIG_BT_MAX_CONN to 2 and it worked as you described. I might try the work approach later, but for now I don't want to deal with any potential race conditions between the disconnection and work.

RE: NRF52840: NCS 2.5.0 -> NCS 2.7.0 BLE advertising stops on disconnect

Susheel Nuguru — Mon, 26 Aug 2024 11:50:47 GMT

The disconnect probably is not complete if you do start to advertise in the disconnect callback with CONFIG_BT_MAX_CONN set to 1. This is because you cannot do a connectable advertising while the controller is not fully finished with the disconnect procedure. Which means, you cannot do another connectable advertising while in another connection with max_conn = 1;

Either change CONFIG_BT_MAX_CONN to 2, to allow this overlap of roles or

Create a worker thread to start the advertising after the disconnect callback has exited like below

static K_WORK_DEFINE(start_advertising_worker, start_advertising_coded);

static void start_advertising_coded(struct k_work *work)
{
	int err;

	err = bt_le_ext_adv_start(adv, NULL);
	if (err) {
		printk("Failed to start advertising set (err %d)\n", err);
		return;
	}

	printk("Advertiser %p set started\n", adv);
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	printk("Disconnected (reason 0x%02x)\n", reason);

	k_work_submit(&start_advertising_worker);

}

Where disconnected() is the callback for disconnected which is configured as below

BT_CONN_CB_DEFINE(conn_callbacks) = {
	.connected = connected,
	.disconnected = disconnected,
};