Introduce analog scaling parameter for analog airspeed sensor

src/modules/sensors/sensor_params.c

@@ -194,16 +194,22 @@ PARAM_DEFINE_FLOAT(SENS_ACC_ZSCALE, 1.0f);
 /**
  * Differential pressure sensor offset
  *
+ * The offset (zero-reading) in Pascal
+ *
  * @group Sensor Calibration
  */
 PARAM_DEFINE_FLOAT(SENS_DPRES_OFF, 0.0f);
 
 /**
- * Differential pressure sensor analog enabled
+ * Differential pressure sensor analog scaling
+ *
+ * Pick the appropriate scaling from the datasheet.
+ * this number defines the (linear) conversion from voltage
+ * to Pascal (pa).
  *
  * @group Sensor Calibration
  */
-PARAM_DEFINE_INT32(SENS_DPRES_ANA, 0);
+PARAM_DEFINE_FLOAT(SENS_DPRES_ANSC, 0);
 
 
 /**

src/modules/sensors/sensors.cpp

@@ -248,7 +248,7 @@ private:
 		float accel_offset[3];
 		float accel_scale[3];
 		float diff_pres_offset_pa;
-		float diff_pres_analog_enabled;
+		float diff_pres_analog_scale;
 
 		int board_rotation;
 		int external_mag_rotation;
@@ -311,7 +311,7 @@ private:
 		param_t mag_offset[3];
 		param_t mag_scale[3];
 		param_t diff_pres_offset_pa;
-		param_t diff_pres_analog_enabled;
+		param_t diff_pres_analog_scale;
 
 		param_t rc_map_roll;
 		param_t rc_map_pitch;
@@ -590,7 +590,7 @@ Sensors::Sensors() :
 
 	/* Differential pressure offset */
 	_parameter_handles.diff_pres_offset_pa = param_find("SENS_DPRES_OFF");
-	_parameter_handles.diff_pres_analog_enabled = param_find("SENS_DPRES_ANA");
+	_parameter_handles.diff_pres_analog_scale = param_find("SENS_DPRES_ANSC");
 
 	_parameter_handles.battery_voltage_scaling = param_find("BAT_V_SCALING");
 	_parameter_handles.battery_current_scaling = param_find("BAT_C_SCALING");
@@ -798,7 +798,7 @@ Sensors::parameters_update()
 
 	/* Airspeed offset */
 	param_get(_parameter_handles.diff_pres_offset_pa, &(_parameters.diff_pres_offset_pa));
-	param_get(_parameter_handles.diff_pres_analog_enabled, &(_parameters.diff_pres_analog_enabled));
+	param_get(_parameter_handles.diff_pres_analog_scale, &(_parameters.diff_pres_analog_scale));
 
 	/* scaling of ADC ticks to battery voltage */
 	if (param_get(_parameter_handles.battery_voltage_scaling, &(_parameters.battery_voltage_scaling)) != OK) {
@@ -1330,15 +1330,15 @@ Sensors::adc_poll(struct sensor_combined_s &raw)
 					 * a valid voltage from a connected sensor. Also assume a non-
 					 * zero offset from the sensor if its connected.
 					 */
-					if (voltage > 0.4f && (_parameters.diff_pres_analog_enabled > 0)) {
+					if (voltage > 0.4f && (_parameters.diff_pres_analog_scale > 0)) {
 
-						float diff_pres_pa = voltage * 1000.0f - _parameters.diff_pres_offset_pa; //for MPXV7002DP sensor
+						float diff_pres_pa = voltage * _parameters.diff_pres_analog_scale;
 
 						_diff_pres.timestamp = t;
-						_diff_pres.differential_pressure_pa = diff_pres_pa;
+						_diff_pres.differential_pressure_pa = diff_pres_pa - _parameters.diff_pres_offset_pa;
+						_diff_pres.differential_pressure_raw_pa = diff_pres_pa;
 						_diff_pres.differential_pressure_filtered_pa = diff_pres_pa;
 						_diff_pres.temperature = -1000.0f;
-						_diff_pres.voltage = voltage;
 
 						/* announce the airspeed if needed, just publish else */
 						if (_diff_pres_pub > 0) {