nus_send_enabled_cb invoked before connected

[jhc]

Hi

In my firmware, i setup a NUS service, piece of code as below:

...

static struct bt_nus_cb nus_cb = {
	.sent = nus_sent_cb,
	.send_enabled = nus_send_enabled_cb,
	.received = nus_receive_cb,
};

...

static struct bt_conn_cb conn_callbacks = {
    .connected = connected,
    .disconnected = disconnected,
    .le_param_req = le_param_req,
    .le_param_updated = le_param_updated,

#if defined(CONFIG_BT_SMP)
    .security_changed = security_changed,
#endif /* CONFIG_BT_SMP */

#if defined(CONFIG_BT_USER_PHY_UPDATE)
    .le_phy_updated = le_phy_updated,
#endif /* CONFIG_BT_USER_PHY_UPDATE */

#if defined(CONFIG_BT_USER_DATA_LEN_UPDATE)
    .le_data_len_updated = le_data_len_updated,
#endif /* CONFIG_BT_USER_DATA_LEN_UPDATE */
};

...

int main()
{
...
    bt_conn_cb_register(&conn_callbacks);
...
    bt_nus_init(&nus_cb);
...
}

I found that the nus_send_enabled_cb function is always invoked before connected function in ncs sdk v2.0.0.

In my mind, it should be connected first, then ccc_cfg_changed of service can be called. Is it right?

logo

[Hung Bui]

Hi Jh, 
How did you tested ? 
I did a quick test here with the peripheral_uart (added send_enabled() callback)  and the central_uart and here is what I saw in the log: 

Or this after security is removed: 

[jhc]

Hi, Hung Bui

Our project integrated Multi-link and Central and Peripheral role features.

There are some reference codes, 

static void connected(struct bt_conn *conn, uint8_t conn_err)
{
	char addr[BT_ADDR_LE_STR_LEN];
	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	struct bt_conn_info info;
	bt_conn_get_info(conn, &info);

	if (conn_err) {
		LOG_WRN("Failed to connect to %s error %u", log_strdup(addr), conn_err);
		if(info.role == BT_CONN_ROLE_CENTRAL) {
			start_scan();
			return;
		}
	}

	struct bt_conn *cur_conn = bt_conn_ref(conn);

	if(info.role == BT_CONN_ROLE_CENTRAL) {

		central_conn_count++;
		LOG_INF("CENTRAL(%u), connected: %s", central_conn_count, log_strdup(addr));

	} else {

		peripheral_conn_count++;

		peri_conn = cur_conn;
		
		LOG_INF("PERIPHERAL(%u), connected: %s", peripheral_conn_count, log_strdup(addr));

		request_security(conn);
	}

#if defined(CONFIG_BT_GATT_CLIENT)
	mtu_exchange(conn);
#endif
}


static void discovery_completed_cb(struct bt_gatt_dm *dm, void *context)
{
	int err;
	char uuid_str[37];

	const struct bt_gatt_dm_attr *gatt_service_attr = bt_gatt_dm_service_get(dm);
	const struct bt_gatt_service_val *gatt_service = bt_gatt_dm_attr_service_val(gatt_service_attr);

	size_t attr_count = bt_gatt_dm_attr_cnt(dm);

	bt_uuid_to_str(gatt_service->uuid, uuid_str, sizeof(uuid_str));
	//LOG_INF("Discovery found service %s, attribute count %d", log_strdup(uuid_str), attr_count);


	struct bt_conn* conn = bt_gatt_dm_conn_get(dm);
	struct bt_conn_info info;
	bt_conn_get_info(conn, &info);
	uint8_t conn_index = bt_conn_index(conn);

	if(info.role == BT_CONN_ROLE_CENTRAL) {

		if(bt_uuid_cmp(gatt_service->uuid, BT_UUID_NUS_SERVICE) == 0) {

			LOG_INF("Discovery found NUS...");

			err = bt_nus_handles_assign(dm, &nus_clients[conn_index]);
			if (err) {
				LOG_WRN("Could not assign nus client object: err %d", err);
			}

			err = bt_nus_subscribe_receive(&nus_clients[conn_index]);

		} else if(bt_uuid_cmp(gatt_service->uuid, BT_UUID_ANCS) == 0) {

		}
	}

	bt_gatt_dm_data_print(dm);
	bt_gatt_dm_data_release(dm);

	bt_gatt_dm_continue(dm, NULL);
}
static void nus_send_enabled_cb(enum bt_nus_send_status status)
{
	LOG_INF("nus send status changed: %d", (status==BT_NUS_SEND_STATUS_ENABLED));
}

You can see that the bt_nus_subscribe_receive function will not be called until the NUS service was found in the Central unit.

The log is from the Peripheral unit: