Merged ETS airspeed driver

9 files changed, 180 insertions, 62 deletions

diff --git a/src/modules/commander/commander.c b/src/modules/commander/commander.c
index 0f18d6cef..01ab9e3d9 100644
--- a/src/modules/commander/commander.c
+++ b/src/modules/commander/commander.c
@@ -676,22 +676,22 @@ void do_airspeed_calibration(int status_pub, struct vehicle_status_s *status)
 
 	const int calibration_count = 2500;
 
-	int sub_differential_pressure = orb_subscribe(ORB_ID(differential_pressure));
-	struct differential_pressure_s differential_pressure;
+	int diff_pres_sub = orb_subscribe(ORB_ID(differential_pressure));
+	struct differential_pressure_s diff_pres;
 
 	int calibration_counter = 0;
-	float airspeed_offset = 0.0f;
+	float diff_pres_offset = 0.0f;
 
 	while (calibration_counter < calibration_count) {
 
 		/* wait blocking for new data */
-		struct pollfd fds[1] = { { .fd = sub_differential_pressure, .events = POLLIN } };
+		struct pollfd fds[1] = { { .fd = diff_pres_sub, .events = POLLIN } };
 
 		int poll_ret = poll(fds, 1, 1000);
 
 		if (poll_ret) {
-			orb_copy(ORB_ID(differential_pressure), sub_differential_pressure, &differential_pressure);
-			airspeed_offset += differential_pressure.voltage;
+			orb_copy(ORB_ID(differential_pressure), diff_pres_sub, &diff_pres);
+			diff_pres_offset += diff_pres.differential_pressure_pa;
 			calibration_counter++;
 
 		} else if (poll_ret == 0) {
@@ -701,11 +701,11 @@ void do_airspeed_calibration(int status_pub, struct vehicle_status_s *status)
 		}
 	}
 
-	airspeed_offset = airspeed_offset / calibration_count;
+	diff_pres_offset = diff_pres_offset / calibration_count;
 
-	if (isfinite(airspeed_offset)) {
+	if (isfinite(diff_pres_offset)) {
 
-		if (param_set(param_find("SENS_VAIR_OFF"), &(airspeed_offset))) {
+		if (param_set(param_find("SENS_DPRES_OFF"), &(diff_pres_offset))) {
 			mavlink_log_critical(mavlink_fd, "Setting offs failed!");
 		}
 
@@ -735,7 +735,7 @@ void do_airspeed_calibration(int status_pub, struct vehicle_status_s *status)
 	status->flag_preflight_airspeed_calibration = false;
 	state_machine_publish(status_pub, status, mavlink_fd);
 
-	close(sub_differential_pressure);
+	close(diff_pres_sub);
 }
 
 
@@ -1356,10 +1356,10 @@ int commander_thread_main(int argc, char *argv[])
 	struct sensor_combined_s sensors;
 	memset(&sensors, 0, sizeof(sensors));
 
-	int differential_pressure_sub = orb_subscribe(ORB_ID(differential_pressure));
-	struct differential_pressure_s differential_pressure;
-	memset(&differential_pressure, 0, sizeof(differential_pressure));
-	uint64_t last_differential_pressure_time = 0;
+	int diff_pres_sub = orb_subscribe(ORB_ID(differential_pressure));
+	struct differential_pressure_s diff_pres;
+	memset(&diff_pres, 0, sizeof(diff_pres));
+	uint64_t last_diff_pres_time = 0;
 
 	/* Subscribe to command topic */
 	int cmd_sub = orb_subscribe(ORB_ID(vehicle_command));
@@ -1414,11 +1414,11 @@ int commander_thread_main(int argc, char *argv[])
 			orb_copy(ORB_ID(sensor_combined), sensor_sub, &sensors);
 		}
 
-		orb_check(differential_pressure_sub, &new_data);
+		orb_check(diff_pres_sub, &new_data);
 
 		if (new_data) {
-			orb_copy(ORB_ID(differential_pressure), differential_pressure_sub, &differential_pressure);
-			last_differential_pressure_time = differential_pressure.timestamp;
+			orb_copy(ORB_ID(differential_pressure), diff_pres_sub, &diff_pres);
+			last_diff_pres_time = diff_pres.timestamp;
 		}
 
 		orb_check(cmd_sub, &new_data);
@@ -1633,7 +1633,7 @@ int commander_thread_main(int argc, char *argv[])
 		}
 
 		/* Check for valid airspeed/differential pressure measurements */
-		if (hrt_absolute_time() - last_differential_pressure_time < 2000000) {
+		if (hrt_absolute_time() - last_diff_pres_time < 2000000) {
 			current_status.flag_airspeed_valid = true;
 
 		} else {
diff --git a/src/modules/sdlog/sdlog.c b/src/modules/sdlog/sdlog.c
index df8745d9f..84a9eb6ac 100644
--- a/src/modules/sdlog/sdlog.c
+++ b/src/modules/sdlog/sdlog.c
@@ -71,6 +71,7 @@
 #include <uORB/topics/optical_flow.h>
 #include <uORB/topics/battery_status.h>
 #include <uORB/topics/differential_pressure.h>
+#include <uORB/topics/airspeed.h>
 
 #include <systemlib/systemlib.h>
 
@@ -443,7 +444,8 @@ int sdlog_thread_main(int argc, char *argv[])
 		struct vehicle_vicon_position_s vicon_pos;
 		struct optical_flow_s flow;
 		struct battery_status_s batt;
-		struct differential_pressure_s diff_pressure;
+		struct differential_pressure_s diff_pres;
+		struct airspeed_s airspeed;
 	} buf;
 	memset(&buf, 0, sizeof(buf));
 
@@ -461,7 +463,8 @@ int sdlog_thread_main(int argc, char *argv[])
 		int vicon_pos_sub;
 		int flow_sub;
 		int batt_sub;
-		int diff_pressure_sub;
+		int diff_pres_sub;
+		int airspeed_sub;
 	} subs;
 
 	/* --- MANAGEMENT - LOGGING COMMAND --- */
@@ -558,11 +561,18 @@ int sdlog_thread_main(int argc, char *argv[])
 
 	/* --- DIFFERENTIAL PRESSURE --- */
 	/* subscribe to ORB for flow measurements */
-	subs.diff_pressure_sub = orb_subscribe(ORB_ID(differential_pressure));
-	fds[fdsc_count].fd = subs.diff_pressure_sub;
+	subs.diff_pres_sub = orb_subscribe(ORB_ID(differential_pressure));
+	fds[fdsc_count].fd = subs.diff_pres_sub;
 	fds[fdsc_count].events = POLLIN;
 	fdsc_count++;
 
+	/* --- AIRSPEED --- */
+	/* subscribe to ORB for airspeed */
+	subs.airspeed_sub = orb_subscribe(ORB_ID(airspeed));
+	fds[fdsc_count].fd = subs.airspeed_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;	
+
 	/* WARNING: If you get the error message below,
 	 * then the number of registered messages (fdsc)
 	 * differs from the number of messages in the above list.
@@ -654,7 +664,8 @@ int sdlog_thread_main(int argc, char *argv[])
 				orb_copy(ORB_ID(vehicle_attitude), subs.att_sub, &buf.att);
 				orb_copy(ORB_ID(vehicle_vicon_position), subs.vicon_pos_sub, &buf.vicon_pos);
 				orb_copy(ORB_ID(optical_flow), subs.flow_sub, &buf.flow);
-				orb_copy(ORB_ID(differential_pressure), subs.diff_pressure_sub, &buf.diff_pressure);
+				orb_copy(ORB_ID(differential_pressure), subs.diff_pres_sub, &buf.diff_pres);
+				orb_copy(ORB_ID(airspeed), subs.airspeed_sub, &buf.airspeed);
 				orb_copy(ORB_ID(battery_status), subs.batt_sub, &buf.batt);
 
 				/* if skipping is on or logging is disabled, ignore */
@@ -691,9 +702,9 @@ int sdlog_thread_main(int argc, char *argv[])
 					.vicon = {buf.vicon_pos.x, buf.vicon_pos.y, buf.vicon_pos.z, buf.vicon_pos.roll, buf.vicon_pos.pitch, buf.vicon_pos.yaw},
 					.control_effective = {buf.act_controls_effective.control_effective[0], buf.act_controls_effective.control_effective[1], buf.act_controls_effective.control_effective[2], buf.act_controls_effective.control_effective[3]},
 					.flow = {buf.flow.flow_raw_x, buf.flow.flow_raw_y, buf.flow.flow_comp_x_m, buf.flow.flow_comp_y_m, buf.flow.ground_distance_m, buf.flow.quality},
-					.diff_pressure = buf.diff_pressure.differential_pressure_mbar,
-					.ind_airspeed = buf.diff_pressure.indicated_airspeed_m_s,
-					.true_airspeed = buf.diff_pressure.true_airspeed_m_s
+					.diff_pressure = buf.diff_pres.differential_pressure_pa,
+					.ind_airspeed = buf.airspeed.indicated_airspeed_m_s,
+					.true_airspeed = buf.airspeed.true_airspeed_m_s
 				};
 
 				/* put into buffer for later IO */
diff --git a/src/modules/sensors/sensor_params.c b/src/modules/sensors/sensor_params.c
index c850e3a1e..230060148 100644
--- a/src/modules/sensors/sensor_params.c
+++ b/src/modules/sensors/sensor_params.c
@@ -64,7 +64,7 @@ PARAM_DEFINE_FLOAT(SENS_ACC_XSCALE, 1.0f);
 PARAM_DEFINE_FLOAT(SENS_ACC_YSCALE, 1.0f);
 PARAM_DEFINE_FLOAT(SENS_ACC_ZSCALE, 1.0f);
 
-PARAM_DEFINE_FLOAT(SENS_VAIR_OFF, 2.5f);
+PARAM_DEFINE_INT32(SENS_DPRES_OFF, 1667);
 
 PARAM_DEFINE_FLOAT(RC1_MIN, 1000.0f);
 PARAM_DEFINE_FLOAT(RC1_TRIM, 1500.0f);
diff --git a/src/modules/sensors/sensors.cpp b/src/modules/sensors/sensors.cpp
index 123bbb120..6b6aeedee 100644
--- a/src/modules/sensors/sensors.cpp
+++ b/src/modules/sensors/sensors.cpp
@@ -77,6 +77,7 @@
 #include <uORB/topics/parameter_update.h>
 #include <uORB/topics/battery_status.h>
 #include <uORB/topics/differential_pressure.h>
+#include <uORB/topics/airspeed.h>
 
 #define GYRO_HEALTH_COUNTER_LIMIT_ERROR 20   /* 40 ms downtime at 500 Hz update rate   */
 #define ACC_HEALTH_COUNTER_LIMIT_ERROR  20   /* 40 ms downtime at 500 Hz update rate   */
@@ -98,6 +99,12 @@
 #define BAT_VOL_LOWPASS_2 0.01f
 #define VOLTAGE_BATTERY_IGNORE_THRESHOLD_VOLTS 3.5f
 
+/**
+ * HACK - true temperature is much less than indicated temperature in baro,
+ * subtract 5 degrees in an attempt to account for the electrical upheating of the PCB
+ */
+#define PCB_TEMP_ESTIMATE_DEG 5.0f
+
 #define PPM_INPUT_TIMEOUT_INTERVAL	50000 /**< 50 ms timeout / 20 Hz */
 
 #define limit_minus_one_to_one(arg) (arg < -1.0f) ? -1.0f : ((arg > 1.0f) ? 1.0f : arg)
@@ -156,6 +163,8 @@ private:
 	int		_mag_sub;			/**< raw mag data subscription */
 	int 		_rc_sub;			/**< raw rc channels data subscription */
 	int		_baro_sub;			/**< raw baro data subscription */
+	int     _airspeed_sub;		/**< airspeed subscription */
+	int		_diff_pres_sub;		/**< raw differential pressure subscription */
 	int		_vstatus_sub;			/**< vehicle status subscription */
 	int 		_params_sub;			/**< notification of parameter updates */
 	int 		_manual_control_sub;			/**< notification of manual control updates */
@@ -165,13 +174,15 @@ private:
 	orb_advert_t	_rc_pub;			/**< raw r/c control topic */
 	orb_advert_t	_battery_pub;			/**< battery status */
 	orb_advert_t	_airspeed_pub;			/**< airspeed */
+	orb_advert_t	_diff_pres_pub;			/**< differential_pressure */
 
 	perf_counter_t	_loop_perf;			/**< loop performance counter */
 
 	struct rc_channels_s _rc;			/**< r/c channel data */
 	struct battery_status_s _battery_status;	/**< battery status */
 	struct baro_report _barometer;			/**< barometer data */
-	struct differential_pressure_s _differential_pressure;
+	struct differential_pressure_s _diff_pres;
+	struct airspeed_s _airspeed;
 
 	struct {
 		float min[_rc_max_chan_count];
@@ -187,7 +198,7 @@ private:
 		float mag_scale[3];
 		float accel_offset[3];
 		float accel_scale[3];
-		float airspeed_offset;
+		int diff_pres_offset_pa;
 
 		int rc_type;
 
@@ -236,7 +247,7 @@ private:
 		param_t accel_scale[3];
 		param_t mag_offset[3];
 		param_t mag_scale[3];
-		param_t airspeed_offset;
+		param_t diff_pres_offset_pa;
 
 		param_t rc_map_roll;
 		param_t rc_map_pitch;
@@ -331,6 +342,14 @@ private:
 	void		baro_poll(struct sensor_combined_s &raw);
 
 	/**
+	 * Poll the differential pressure sensor for updated data.
+	 *
+	 * @param raw			Combined sensor data structure into which
+	 *				data should be returned.
+	 */
+	void		diff_pres_poll(struct sensor_combined_s &raw);
+
+	/**
 	 * Check for changes in vehicle status.
 	 */
 	void		vehicle_status_poll();
@@ -400,6 +419,7 @@ Sensors::Sensors() :
 	_rc_pub(-1),
 	_battery_pub(-1),
 	_airspeed_pub(-1),
+	_diff_pres_pub(-1),
 
 /* performance counters */
 	_loop_perf(perf_alloc(PC_ELAPSED, "sensor task update"))
@@ -484,8 +504,8 @@ Sensors::Sensors() :
 	_parameter_handles.mag_scale[1] = param_find("SENS_MAG_YSCALE");
 	_parameter_handles.mag_scale[2] = param_find("SENS_MAG_ZSCALE");
 
-	/*Airspeed offset */
-	_parameter_handles.airspeed_offset = param_find("SENS_VAIR_OFF");
+	/* Differential pressure offset */
+	_parameter_handles.diff_pres_offset_pa = param_find("SENS_DPRES_OFF");
 
 	_parameter_handles.battery_voltage_scaling = param_find("BAT_V_SCALING");
 
@@ -695,7 +715,7 @@ Sensors::parameters_update()
 	param_get(_parameter_handles.mag_scale[2], &(_parameters.mag_scale[2]));
 
 	/* Airspeed offset */
-	param_get(_parameter_handles.airspeed_offset, &(_parameters.airspeed_offset));
+	param_get(_parameter_handles.diff_pres_offset_pa, &(_parameters.diff_pres_offset_pa));
 
 	/* scaling of ADC ticks to battery voltage */
 	if (param_get(_parameter_handles.battery_voltage_scaling, &(_parameters.battery_voltage_scaling)) != OK) {
@@ -890,6 +910,32 @@ Sensors::baro_poll(struct sensor_combined_s &raw)
 }
 
 void
+Sensors::diff_pres_poll(struct sensor_combined_s &raw)
+{
+	bool updated;
+	orb_check(_diff_pres_sub, &updated);
+
+	if (updated) {
+		orb_copy(ORB_ID(differential_pressure), _diff_pres_sub, &_diff_pres);
+
+		raw.differential_pressure_pa = _diff_pres.differential_pressure_pa;
+		raw.differential_pressure_counter++;
+
+		_airspeed.indicated_airspeed_m_s = calc_indicated_airspeed(_diff_pres.differential_pressure_pa);
+		_airspeed.true_airspeed_m_s = calc_true_airspeed(_diff_pres.differential_pressure_pa + raw.baro_pres_mbar*1e2f, 
+											 			 raw.baro_pres_mbar*1e2f, raw.baro_temp_celcius - PCB_TEMP_ESTIMATE_DEG);
+
+		/* announce the airspeed if needed, just publish else */
+		if (_airspeed_pub > 0) {
+			orb_publish(ORB_ID(airspeed), _airspeed_pub, &_airspeed);
+
+		} else {
+			_airspeed_pub = orb_advertise(ORB_ID(airspeed), &_airspeed);
+		}
+	}
+}
+
+void
 Sensors::vehicle_status_poll()
 {
 	struct vehicle_status_s vstatus;
@@ -1047,31 +1093,18 @@ Sensors::adc_poll(struct sensor_combined_s &raw)
 					 */
 					if (voltage > 0.4f) {
 
-						float diff_pres_pa = (voltage - _parameters.airspeed_offset) * 1000.0f; //for MPXV7002DP sensor
-
-						float airspeed_true = calc_true_airspeed(diff_pres_pa + _barometer.pressure*1e2f,
-							_barometer.pressure*1e2f, _barometer.temperature - 5.0f); //factor 1e2 for conversion from mBar to Pa
-						// XXX HACK - true temperature is much less than indicated temperature in baro,
-						// subtract 5 degrees in an attempt to account for the electrical upheating of the PCB
+						float diff_pres_pa = voltage * 1000.0f - _parameters.diff_pres_offset_pa; //for MPXV7002DP sensor
 
-						float airspeed_indicated = calc_indicated_airspeed(diff_pres_pa);
-
-						//printf("voltage: %.4f, diff_pres_pa %.4f, baro press %.4f Pa, v_ind %.4f, v_true %.4f\n", (double)voltage, (double)diff_pres_pa, (double)_barometer.pressure*1e2f, (double)airspeed_indicated, (double)airspeed_true);
-
-						_differential_pressure.timestamp = hrt_absolute_time();
-						_differential_pressure.static_pressure_mbar = _barometer.pressure;
-						_differential_pressure.differential_pressure_mbar = diff_pres_pa*1e-2f;
-						_differential_pressure.temperature_celcius = _barometer.temperature;
-						_differential_pressure.indicated_airspeed_m_s = airspeed_indicated;
-						_differential_pressure.true_airspeed_m_s = airspeed_true;
-						_differential_pressure.voltage = voltage;
+						_diff_pres.timestamp = hrt_absolute_time();
+						_diff_pres.differential_pressure_pa = diff_pres_pa;
+						_diff_pres.voltage = voltage;
 
 						/* announce the airspeed if needed, just publish else */
-						if (_airspeed_pub > 0) {
-							orb_publish(ORB_ID(differential_pressure), _airspeed_pub, &_differential_pressure);
+						if (_diff_pres_pub > 0) {
+							orb_publish(ORB_ID(differential_pressure), _diff_pres_pub, &_diff_pres);
 
 						} else {
-							_airspeed_pub = orb_advertise(ORB_ID(differential_pressure), &_differential_pressure);
+							_diff_pres_pub = orb_advertise(ORB_ID(differential_pressure), &_diff_pres);
 						}
 					}
 				}
@@ -1310,6 +1343,7 @@ Sensors::task_main()
 	_mag_sub = orb_subscribe(ORB_ID(sensor_mag));
 	_rc_sub = orb_subscribe(ORB_ID(input_rc));
 	_baro_sub = orb_subscribe(ORB_ID(sensor_baro));
+	_diff_pres_sub = orb_subscribe(ORB_ID(differential_pressure));
 	_vstatus_sub = orb_subscribe(ORB_ID(vehicle_status));
 	_params_sub = orb_subscribe(ORB_ID(parameter_update));
 	_manual_control_sub = orb_subscribe(ORB_ID(manual_control_setpoint));
@@ -1336,6 +1370,7 @@ Sensors::task_main()
 	gyro_poll(raw);
 	mag_poll(raw);
 	baro_poll(raw);
+	diff_pres_poll(raw);
 
 	parameter_update_poll(true /* forced */);
 
@@ -1384,6 +1419,8 @@ Sensors::task_main()
 		/* check battery voltage */
 		adc_poll(raw);
 
+		diff_pres_poll(raw);
+
 		/* Inform other processes that new data is available to copy */
 		if (_publishing)
 			orb_publish(ORB_ID(sensor_combined), _sensor_pub, &raw);
diff --git a/src/modules/systemlib/airspeed.c b/src/modules/systemlib/airspeed.c
index 264287b10..15bb833a9 100644
--- a/src/modules/systemlib/airspeed.c
+++ b/src/modules/systemlib/airspeed.c
@@ -97,7 +97,7 @@ float calc_true_airspeed(float total_pressure, float static_pressure, float temp
 	float density = get_air_density(static_pressure, temperature_celsius);
 	if (density < 0.0001f || !isfinite(density)) {
 	 density = CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C;
-	 printf("[airspeed] Invalid air density, using density at sea level\n");
+//	 printf("[airspeed] Invalid air density, using density at sea level\n");
 	}
 
 	float pressure_difference = total_pressure - static_pressure;
diff --git a/src/modules/uORB/objects_common.cpp b/src/modules/uORB/objects_common.cpp
index 136375140..4197f6fb2 100644
--- a/src/modules/uORB/objects_common.cpp
+++ b/src/modules/uORB/objects_common.cpp
@@ -122,6 +122,9 @@ ORB_DEFINE(optical_flow, struct optical_flow_s);
 #include "topics/omnidirectional_flow.h"
 ORB_DEFINE(omnidirectional_flow, struct omnidirectional_flow_s);
 
+#include "topics/airspeed.h"
+ORB_DEFINE(airspeed, struct airspeed_s);
+
 #include "topics/differential_pressure.h"
 ORB_DEFINE(differential_pressure, struct differential_pressure_s);
 
diff --git a/src/modules/uORB/topics/airspeed.h b/src/modules/uORB/topics/airspeed.h
new file mode 100644
index 000000000..a3da3758f
--- /dev/null
+++ b/src/modules/uORB/topics/airspeed.h
@@ -0,0 +1,67 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012-2013 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file airspeed.h
+ *
+ * Definition of airspeed topic
+ */
+
+#ifndef TOPIC_AIRSPEED_H_
+#define TOPIC_AIRSPEED_H_
+
+#include "../uORB.h"
+#include <stdint.h>
+
+/**
+ * @addtogroup topics
+ * @{
+ */
+
+/**
+ * Airspeed
+ */
+struct airspeed_s {
+	uint64_t	timestamp;					/**< microseconds since system boot, needed to integrate */
+	float		indicated_airspeed_m_s;		/**< indicated airspeed in meters per second, -1 if unknown	 */
+	float		true_airspeed_m_s;			/**< true airspeed in meters per second, -1 if unknown */
+};
+
+/**
+ * @}
+ */
+
+/* register this as object request broker structure */
+ORB_DECLARE(airspeed);
+
+#endif
diff --git a/src/modules/uORB/topics/differential_pressure.h b/src/modules/uORB/topics/differential_pressure.h
index d5e4bf37e..8ce85213b 100644
--- a/src/modules/uORB/topics/differential_pressure.h
+++ b/src/modules/uORB/topics/differential_pressure.h
@@ -49,16 +49,14 @@
  */
 
 /**
- * Differential pressure and airspeed
+ * Differential pressure.
  */
 struct differential_pressure_s {
-	uint64_t	timestamp;					/**< microseconds since system boot, needed to integrate */
-	float   	static_pressure_mbar;		/**< Static / environment pressure */
-	float		differential_pressure_mbar;	/**< Differential pressure reading */
-	float		temperature_celcius;		/**< ambient temperature in celcius, -1 if unknown */
-	float		indicated_airspeed_m_s;		/**< indicated airspeed in meters per second, -1 if unknown	 */
-	float		true_airspeed_m_s;			/**< true airspeed in meters per second, -1 if unknown */
-	float		voltage;					/**< Voltage from the airspeed sensor (voltage divider already compensated) */
+	uint64_t	timestamp;						/**< microseconds since system boot, needed to integrate */
+	uint16_t	differential_pressure_pa;		/**< Differential pressure reading */
+	uint16_t	max_differential_pressure_pa;	/**< Maximum differential pressure reading */
+	float		voltage;						/**< Voltage from analog airspeed sensors (voltage divider already compensated) */
+
 };
 
 /**
diff --git a/src/modules/uORB/topics/sensor_combined.h b/src/modules/uORB/topics/sensor_combined.h
index 961ee8b4a..9a76b5182 100644
--- a/src/modules/uORB/topics/sensor_combined.h
+++ b/src/modules/uORB/topics/sensor_combined.h
@@ -103,6 +103,8 @@ struct sensor_combined_s {
 	float mcu_temp_celcius;			/**< Internal temperature measurement of MCU */
 	uint32_t baro_counter;			/**< Number of raw baro measurements taken        */
 
+	float differential_pressure_pa;				/**< Airspeed sensor differential pressure                  */ 
+	uint32_t differential_pressure_counter;		/**< Number of raw differential pressure measurements taken */
 };
 
 /**