bluetooth: samples: Use real-time ranging data in RAS samples

Using real-time ranging data instead of on-demand:
- requires fewer subscriptions
- requires less complex logic for combining the local and remote results
  since the application no longer needs to initiate a data fetch through
  RAS-CP
- Doubles the maximum frequency of channel sounding procedures by
  making it possible to use less than half the procedure interval while
  still having enough time to finish the GATT transaction and distance
  estimation before the next procedure begins.

Signed-off-by: Olivier Lesage <[email protected]>

Author: olivier-le-sage

include/bluetooth/services/ras.h

@@ -90,6 +90,14 @@ extern "C" {
 	 (BT_RAS_MAX_STEPS_PER_PROCEDURE * BT_RAS_STEP_MODE_LEN) +                                 \
 	 (BT_RAS_MAX_STEPS_PER_PROCEDURE * BT_RAS_MAX_STEP_DATA_LEN))
 
+/** @brief RAS Features as defined in RAS Specification, Table 3.3. */
+enum ras_feat {
+	RAS_FEAT_REALTIME_RD          = BIT(0),
+	RAS_FEAT_RETRIEVE_LOST_RD_SEG = BIT(1),
+	RAS_FEAT_ABORT_OP             = BIT(2),
+	RAS_FEAT_FILTER_RD            = BIT(3),
+};
+
 /** @brief Ranging Header structure as defined in RAS Specification, Table 3.7. */
 struct ras_ranging_header {
 	/** Ranging Counter is lower 12-bits of CS Procedure_Counter provided by the Core Controller
@@ -333,7 +341,7 @@ typedef void (*bt_ras_rreq_rd_overwritten_cb_t)(struct bt_conn *conn, uint16_t r
  * the peer.
  *
  * @param[in] conn            Connection Object.
- * @param[in] ranging_counter Ranging counter which has been received.
+ * @param[in] ranging_counter Ranging counter that has been received.
  * @param[in] err             Error code, 0 if successful. Otherwise a negative error code.
  */
 typedef void (*bt_ras_rreq_ranging_data_received_t)(struct bt_conn *conn, uint16_t ranging_counter,
@@ -372,7 +380,7 @@ int bt_ras_rreq_alloc_and_assign_handles(struct bt_gatt_dm *dm, struct bt_conn *
  * characteristic to which the device is already subscribed or unsubscribed (respectively).
  *
  * @param[in] conn Connection object.
- * @param[in] subscription_change_cb CCC write request response callback
+ * @param[in] subscription_change_cb CCC write request response callback.
  *
  * @retval 0 If the operation was successful.
  *           Otherwise, a negative error code is returned.
@@ -525,7 +533,7 @@ int bt_ras_rreq_rd_overwritten_unsubscribe(struct bt_conn *conn);
  * @note The data callback will be called many times (for as long as the RRSP continues
  *       to send notifications).
  *
- * @param[in] conn Connection Object, which already has associated RREQ context.
+ * @param[in] conn Connection Object that already has an associated RREQ context.
  * @param[in] ranging_data_out     Simple buffer to store received ranging data.
  * @param[in] data_received_cb     Callback called when complete ranging data is received.
  *
@@ -540,7 +548,7 @@ int bt_ras_rreq_realtime_rd_subscribe(struct bt_conn *conn, struct net_buf_simpl
  * @note Calling from BT RX thread may return an error as bt_gatt_unsubscribe will not block if
  * there are no available TX buffers.
  *
- * @param[in] conn Connection Object, which already has associated RREQ context.
+ * @param[in] conn Connection Object that already has an associated RREQ context.
  *
  * @retval 0 If the operation was successful.
  *           Otherwise, a negative error code is returned.

samples/bluetooth/channel_sounding_ras_initiator/src/main.c

@@ -44,6 +44,7 @@ static K_SEM_DEFINE(sem_connected, 0, 1);
 static K_SEM_DEFINE(sem_discovery_done, 0, 1);
 static K_SEM_DEFINE(sem_mtu_exchange_done, 0, 1);
 static K_SEM_DEFINE(sem_security, 0, 1);
+static K_SEM_DEFINE(sem_ras_features, 0, 1);
 static K_SEM_DEFINE(sem_local_steps, 1, 1);
 
 static K_MUTEX_DEFINE(distance_estimate_buffer_mutex);
@@ -53,6 +54,7 @@ NET_BUF_SIMPLE_DEFINE_STATIC(latest_local_steps, LOCAL_PROCEDURE_MEM);
 NET_BUF_SIMPLE_DEFINE_STATIC(latest_peer_steps, BT_RAS_PROCEDURE_MEM);
 static int32_t most_recent_local_ranging_counter = PROCEDURE_COUNTER_NONE;
 static int32_t dropped_ranging_counter = PROCEDURE_COUNTER_NONE;
+static uint32_t ras_feature_bits;
 
 static uint8_t buffer_index;
 static uint8_t buffer_num_valid;
@@ -121,17 +123,26 @@ static cs_de_dist_estimates_t get_distance(uint8_t ap)
 	return averaged_result;
 }
 
-static void ranging_data_get_complete_cb(struct bt_conn *conn, uint16_t ranging_counter, int err)
+static void ranging_data_cb(struct bt_conn *conn, uint16_t ranging_counter, int err)
 {
 	ARG_UNUSED(conn);
 
 	if (err) {
-		LOG_ERR("Error when getting ranging data with ranging counter %d (err %d)",
+		LOG_ERR("Error when receiving ranging data with ranging counter %d (err %d)",
 			ranging_counter, err);
 		return;
 	}
 
-	LOG_DBG("Ranging data get completed for ranging counter %d", ranging_counter);
+	if (ranging_counter != most_recent_local_ranging_counter) {
+		LOG_INF("Ranging data dropped as peer ranging counter doesn't match local ranging "
+			"data counter. (peer: %u, local: %u)",
+			ranging_counter, most_recent_local_ranging_counter);
+		net_buf_simple_reset(&latest_local_steps);
+		k_sem_give(&sem_local_steps);
+		return;
+	}
+
+	LOG_DBG("Ranging data received for ranging counter %d", ranging_counter);
 
 	/* This struct is static to avoid putting it on the stack (it's very large) */
 	static cs_de_report_t cs_de_report;
@@ -140,7 +151,11 @@ static void ranging_data_get_complete_cb(struct bt_conn *conn, uint16_t ranging_
 			      &cs_de_report);
 
 	net_buf_simple_reset(&latest_local_steps);
-	net_buf_simple_reset(&latest_peer_steps);
+
+	if (ras_feature_bits & RAS_FEAT_REALTIME_RD) {
+		net_buf_simple_reset(&latest_peer_steps);
+	}
+
 	k_sem_give(&sem_local_steps);
 
 	cs_de_quality_t quality = cs_de_calc(&cs_de_report);
@@ -166,7 +181,7 @@ static void subevent_result_cb(struct bt_conn *conn, struct bt_conn_le_cs_subeve
 
 		if (sem_state < 0) {
 			dropped_ranging_counter = result->header.procedure_counter;
-			LOG_DBG("Dropped subevent results due to unfinished ranging data request.");
+			LOG_INF("Dropped subevent results. Waiting for ranging data from peer.");
 			return;
 		}
 
@@ -211,7 +226,7 @@ static void ranging_data_ready_cb(struct bt_conn *conn, uint16_t ranging_counter
 	if (ranging_counter == most_recent_local_ranging_counter) {
 		int err = bt_ras_rreq_cp_get_ranging_data(connection, &latest_peer_steps,
 							  ranging_counter,
-							  ranging_data_get_complete_cb);
+							  ranging_data_cb);
 		if (err) {
 			LOG_ERR("Get ranging data failed (err %d)", err);
 			net_buf_simple_reset(&latest_local_steps);
@@ -404,6 +419,18 @@ static void procedure_enable_cb(struct bt_conn *conn,
 	}
 }
 
+void ras_features_read_cb(struct bt_conn *conn, uint32_t feature_bits, int err)
+{
+	if (err) {
+		LOG_WRN("Error while reading RAS feature bits (err %d)", err);
+	} else {
+		LOG_INF("Read RAS feature bits: 0x%x", feature_bits);
+		ras_feature_bits = feature_bits;
+	}
+
+	k_sem_give(&sem_ras_features);
+}
+
 static void scan_filter_match(struct bt_scan_device_info *device_info,
 			      struct bt_scan_filter_match *filter_match, bool connectable)
 {
@@ -534,28 +561,48 @@ int main(void)
 		return 0;
 	}
 
-	err = bt_ras_rreq_rd_overwritten_subscribe(connection, ranging_data_overwritten_cb);
+	err = bt_ras_rreq_read_features(connection, ras_features_read_cb);
 	if (err) {
-		LOG_ERR("RAS RREQ ranging data overwritten subscribe failed (err %d)", err);
+		LOG_ERR("Could not get RAS features from peer (err %d)", err);
 		return 0;
 	}
 
-	err = bt_ras_rreq_rd_ready_subscribe(connection, ranging_data_ready_cb);
-	if (err) {
-		LOG_ERR("RAS RREQ ranging data ready subscribe failed (err %d)", err);
-		return 0;
-	}
+	k_sem_take(&sem_ras_features, K_FOREVER);
 
-	err = bt_ras_rreq_on_demand_rd_subscribe(connection);
-	if (err) {
-		LOG_ERR("RAS RREQ On-demand ranging data subscribe failed (err %d)", err);
-		return 0;
-	}
+	const bool realtime_rd = ras_feature_bits & RAS_FEAT_REALTIME_RD;
 
-	err = bt_ras_rreq_cp_subscribe(connection);
-	if (err) {
-		LOG_ERR("RAS RREQ CP subscribe failed (err %d)", err);
-		return 0;
+	if (realtime_rd) {
+		err = bt_ras_rreq_realtime_rd_subscribe(connection,
+							&latest_peer_steps,
+							ranging_data_cb);
+		if (err) {
+			LOG_ERR("RAS RREQ Real-time ranging data subscribe failed (err %d)", err);
+			return 0;
+		}
+	} else {
+		err = bt_ras_rreq_rd_overwritten_subscribe(connection, ranging_data_overwritten_cb);
+		if (err) {
+			LOG_ERR("RAS RREQ ranging data overwritten subscribe failed (err %d)", err);
+			return 0;
+		}
+
+		err = bt_ras_rreq_rd_ready_subscribe(connection, ranging_data_ready_cb);
+		if (err) {
+			LOG_ERR("RAS RREQ ranging data ready subscribe failed (err %d)", err);
+			return 0;
+		}
+
+		err = bt_ras_rreq_on_demand_rd_subscribe(connection);
+		if (err) {
+			LOG_ERR("RAS RREQ On-demand ranging data subscribe failed (err %d)", err);
+			return 0;
+		}
+
+		err = bt_ras_rreq_cp_subscribe(connection);
+		if (err) {
+			LOG_ERR("RAS RREQ CP subscribe failed (err %d)", err);
+			return 0;
+		}
 	}
 
 	err = bt_le_cs_read_remote_supported_capabilities(connection);
@@ -605,8 +652,8 @@ int main(void)
 	const struct bt_le_cs_set_procedure_parameters_param procedure_params = {
 		.config_id = CS_CONFIG_ID,
 		.max_procedure_len = 1000,
-		.min_procedure_interval = 10,
-		.max_procedure_interval = 10,
+		.min_procedure_interval = realtime_rd ? 4 : 10,
+		.max_procedure_interval = realtime_rd ? 4 : 10,
 		.max_procedure_count = 0,
 		.min_subevent_len = 60000,
 		.max_subevent_len = 60000,

subsys/bluetooth/services/ras/ras_internal.h

@@ -57,14 +57,6 @@ enum rascp_rsp_code {
 	RASCP_RESPONSE_NO_RECORDS_FOUND        = 0x08,
 };
 
-/** @brief RAS Features as defined in RAS Specification, Table 3.3. */
-enum ras_feat {
-	RAS_FEAT_REALTIME_RD          = BIT(0),
-	RAS_FEAT_RETRIEVE_LOST_RD_SEG = BIT(1),
-	RAS_FEAT_ABORT_OP             = BIT(2),
-	RAS_FEAT_FILTER_RD            = BIT(3),
-};
-
 /** @brief RAS ATT Application error codes as defined in RAS Specification, Table 2.1. */
 enum ras_att_error {
 	RAS_ATT_ERROR_CCC_CONFIG         = 0xFD,

subsys/bluetooth/services/ras/rreq/ras_rreq.c

@@ -195,6 +195,7 @@ static void data_receive_finished(struct bt_ras_rreq *rreq)
 
 	rreq->last_segment_received = false;
 	rreq->next_expected_segment_counter = 0;
+	rreq->data_error_status = 0;
 }
 
 static uint8_t ranging_data_overwritten_notify_func(struct bt_conn *conn,