add param for qnh

src/drivers/ms5611/ms5611.cpp

@@ -130,7 +130,7 @@ protected:
 	float			_T;
 
 	/* altitude conversion calibration */
-	unsigned		_msl_pressure;	/* in kPa */
+	unsigned		_msl_pressure;	/* in Pa */
 
 	orb_advert_t		_baro_topic;
 

src/modules/sensors/sensor_params.c

@@ -214,6 +214,16 @@ PARAM_DEFINE_FLOAT(SENS_DPRES_OFF, 0.0f);
  */
 PARAM_DEFINE_FLOAT(SENS_DPRES_ANSC, 0);
 
+/**
+ * QNH for barometer
+ *
+ * @min 500
+ * @max 1500
+ * @group Sensor Calibration
+ * @unit hPa
+ */
+PARAM_DEFINE_FLOAT(SENS_BARO_QNH, 1013.25f);
+
 
 /**
  * Board rotation

src/modules/sensors/sensors.cpp

@@ -301,6 +301,8 @@ private:
 		float battery_voltage_scaling;
 		float battery_current_scaling;
 
+		float baro_qnh;
+
 	}		_parameters;			/**< local copies of interesting parameters */
 
 	struct {
@@ -357,6 +359,8 @@ private:
 
 		param_t board_offset[3];
 
+		param_t baro_qnh;
+
 	}		_parameter_handles;		/**< handles for interesting parameters */
 
 
@@ -617,6 +621,9 @@ Sensors::Sensors() :
 	_parameter_handles.board_offset[1] = param_find("SENS_BOARD_Y_OFF");
 	_parameter_handles.board_offset[2] = param_find("SENS_BOARD_Z_OFF");
 
+	/* Barometer QNH */
+	_parameter_handles.baro_qnh = param_find("SENS_BARO_QNH");
+
 	/* fetch initial parameter values */
 	parameters_update();
 }
@@ -841,6 +848,23 @@ Sensors::parameters_update()
 
 	_board_rotation = _board_rotation * board_rotation_offset;
 
+	/* update barometer qnh setting */
+	param_get(_parameter_handles.baro_qnh, &(_parameters.baro_qnh));
+	int	fd;
+	fd = open(BARO_DEVICE_PATH, 0);
+	if (fd < 0) {
+		warn("%s", BARO_DEVICE_PATH);
+		errx(1, "FATAL: no barometer found");
+
+	} else {
+		warnx("qnh ioctl, %lu", (unsigned long)(_parameters.baro_qnh * 100));
+		int ret = ioctl(fd, BAROIOCSMSLPRESSURE, (unsigned long)(_parameters.baro_qnh * 100));
+		if (ret) {
+			errx(ret, "qnh could not be set");
+		}
+	}
+	close(fd);
+
 	return OK;
 }