airspeed (pitot) offset calibration

1 files changed, 11 insertions, 2 deletions

diff --git a/apps/sensors/sensors.cpp b/apps/sensors/sensors.cpp
index c29910dcc..f77bc9b8b 100644
--- a/apps/sensors/sensors.cpp
+++ b/apps/sensors/sensors.cpp
@@ -187,6 +187,7 @@ private:
 		float mag_scale[3];
 		float accel_offset[3];
 		float accel_scale[3];
+		float airspeed_offset;
 
 		int rc_type;
 
@@ -235,6 +236,7 @@ private:
 		param_t accel_scale[3];
 		param_t mag_offset[3];
 		param_t mag_scale[3];
+		param_t airspeed_offset;
 
 		param_t rc_map_roll;
 		param_t rc_map_pitch;
@@ -480,6 +482,9 @@ 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");
+
 	_parameter_handles.battery_voltage_scaling = param_find("BAT_V_SCALING");
 
 	/* fetch initial parameter values */
@@ -687,6 +692,9 @@ Sensors::parameters_update()
 	param_get(_parameter_handles.mag_scale[1], &(_parameters.mag_scale[1]));
 	param_get(_parameter_handles.mag_scale[2], &(_parameters.mag_scale[2]));
 
+	/* Airspeed offset */
+	param_get(_parameter_handles.airspeed_offset, &(_parameters.airspeed_offset));
+
 	/* scaling of ADC ticks to battery voltage */
 	if (param_get(_parameter_handles.battery_voltage_scaling, &(_parameters.battery_voltage_scaling)) != OK) {
 		warnx("Failed updating voltage scaling param");
@@ -1036,7 +1044,7 @@ Sensors::adc_poll(struct sensor_combined_s &raw)
 //						float pres_raw = fabsf(voltage - (3.3f / 2.0f));
 //						float pres_mbar = pres_raw * (3.3f / 5.0f) * 10.0f;
 						//XXX depends on sensor used..., where are the above numbers from?
-						float diff_pres_pa = fabsf(voltage - 2.5f) * 1000.0f; //for MPXV7002DP //xxx: need an offset calibration
+						float diff_pres_pa = (voltage - _parameters.airspeed_offset) * 1000.0f; //for MPXV7002DP
 
 						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
@@ -1045,7 +1053,7 @@ Sensors::adc_poll(struct sensor_combined_s &raw)
 
 						float airspeed_indicated = calc_indicated_airspeed(diff_pres_pa);
 
-						//printf("voltage: %.4f, diff_pres_pa %.4f, v_ind %.4f, v_true %.4f\n", (double)voltage, (double)diff_pres_pa, (double)airspeed_indicated, (double)airspeed_true);
+						//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;
@@ -1053,6 +1061,7 @@ Sensors::adc_poll(struct sensor_combined_s &raw)
 						_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;
 
 						/* announce the airspeed if needed, just publish else */
 						if (_airspeed_pub > 0) {