samples: central_uart: Add connection to bonded devices based on address

Change adds reconnect to bonded devices using their address.
The address of bonded devices is added to the scan filters.

Ref: NCSDK-30193

Signed-off-by: Marcin Jelinski <[email protected]>

Author: maje-emb

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -280,6 +280,10 @@ Bluetooth samples
 
   * Added loading of radio trims and a fix of a hardware errata for the nRF54H20 SoC to improve the RF performance.
 
+* :ref:`central_uart` sample:
+
+  * Added reconnection to bonded devices based on their address.
+
 Bluetooth Fast Pair samples
 ---------------------------
 

samples/bluetooth/central_uart/prj.conf

@@ -22,6 +22,7 @@ CONFIG_BT_NUS_CLIENT=y
 CONFIG_BT_SCAN=y
 CONFIG_BT_SCAN_FILTER_ENABLE=y
 CONFIG_BT_SCAN_UUID_CNT=1
+CONFIG_BT_SCAN_ADDRESS_CNT=1
 CONFIG_BT_GATT_DM=y
 CONFIG_HEAP_MEM_POOL_SIZE=2048
 

samples/bluetooth/central_uart/src/main.c

@@ -47,6 +47,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 
 static const struct device *uart = DEVICE_DT_GET(DT_CHOSEN(nordic_nus_uart));
 static struct k_work_delayable uart_work;
+static struct k_work scan_work;
 
 K_SEM_DEFINE(nus_write_sem, 0, 1);
 
@@ -361,11 +362,7 @@ static void connected(struct bt_conn *conn, uint8_t conn_err)
 			bt_conn_unref(default_conn);
 			default_conn = NULL;
 
-			err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
-			if (err) {
-				LOG_ERR("Scanning failed to start (err %d)",
-					err);
-			}
+			(void)k_work_submit(&scan_work);
 		}
 
 		return;
@@ -397,7 +394,6 @@ static void connected(struct bt_conn *conn, uint8_t conn_err)
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
 	char addr[BT_ADDR_LE_STR_LEN];
-	int err;
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
@@ -410,11 +406,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
 
-	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
-	if (err) {
-		LOG_ERR("Scanning failed to start (err %d)",
-			err);
-	}
+	(void)k_work_submit(&scan_work);
 }
 
 static void security_changed(struct bt_conn *conn, bt_security_t level,
@@ -486,32 +478,88 @@ static int nus_client_init(void)
 BT_SCAN_CB_INIT(scan_cb, scan_filter_match, NULL,
 		scan_connecting_error, scan_connecting);
 
-static int scan_init(void)
+static void try_add_address_filter(const struct bt_bond_info *info, void *user_data)
 {
 	int err;
-	struct bt_scan_init_param scan_init = {
-		.connect_if_match = 1,
-	};
+	char addr[BT_ADDR_LE_STR_LEN];
+	uint8_t *filter_mode = user_data;
 
-	bt_scan_init(&scan_init);
-	bt_scan_cb_register(&scan_cb);
+	bt_addr_le_to_str(&info->addr, addr, sizeof(addr));
+
+	struct bt_conn *conn = bt_conn_lookup_addr_le(BT_ID_DEFAULT, &info->addr);
+
+	if (conn) {
+		bt_conn_unref(conn);
+		return;
+	}
+
+	err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_ADDR, &info->addr);
+	if (err) {
+		LOG_ERR("Address filter cannot be added (err %d): %s", err, addr);
+		return;
+	}
+
+	LOG_INF("Address filter added: %s", addr);
+	*filter_mode |= BT_SCAN_ADDR_FILTER;
+}
+
+static int scan_start(void)
+{
+	int err;
+	uint8_t filter_mode = 0;
+
+	err = bt_scan_stop();
+	if (err) {
+		LOG_ERR("Failed to stop scanning (err %d)", err);
+		return err;
+	}
+
+	bt_scan_filter_remove_all();
 
 	err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_UUID, BT_UUID_NUS_SERVICE);
 	if (err) {
-		LOG_ERR("Scanning filters cannot be set (err %d)", err);
+		LOG_ERR("UUID filter cannot be added (err %d", err);
 		return err;
 	}
+	filter_mode |= BT_SCAN_UUID_FILTER;
+
+	bt_foreach_bond(BT_ID_DEFAULT, try_add_address_filter, &filter_mode);
 
-	err = bt_scan_filter_enable(BT_SCAN_UUID_FILTER, false);
+	err = bt_scan_filter_enable(filter_mode, false);
 	if (err) {
 		LOG_ERR("Filters cannot be turned on (err %d)", err);
 		return err;
 	}
 
-	LOG_INF("Scan module initialized");
-	return err;
+	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
+	if (err) {
+		LOG_ERR("Scanning failed to start (err %d)", err);
+		return err;
+	}
+
+	LOG_INF("Scan started");
+	return 0;
 }
 
+static void scan_work_handler(struct k_work *item)
+{
+	ARG_UNUSED(item);
+
+	(void)scan_start();
+}
+
+static void scan_init(void)
+{
+	struct bt_scan_init_param scan_init = {
+		.connect_if_match = true,
+	};
+
+	bt_scan_init(&scan_init);
+	bt_scan_cb_register(&scan_cb);
+
+	k_work_init(&scan_work, scan_work_handler);
+	LOG_INF("Scan module initialized");
+}
 
 static void auth_cancel(struct bt_conn *conn)
 {
@@ -585,27 +633,19 @@ int main(void)
 		return 0;
 	}
 
-	err = scan_init();
-	if (err != 0) {
-		LOG_ERR("scan_init failed (err %d)", err);
-		return 0;
-	}
-
 	err = nus_client_init();
 	if (err != 0) {
 		LOG_ERR("nus_client_init failed (err %d)", err);
 		return 0;
 	}
 
-	printk("Starting Bluetooth Central UART sample\n");
-
-	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
+	scan_init();
+	err = scan_start();
 	if (err) {
-		LOG_ERR("Scanning failed to start (err %d)", err);
 		return 0;
 	}
 
-	LOG_INF("Scanning successfully started");
+	printk("Starting Bluetooth Central UART sample\n");
 
 	struct uart_data_t nus_data = {
 		.len = 0,