Merge remote-tracking branch 'px4/master' into navigator_rewrite

Conflicts:
	src/modules/navigator/navigator_main.cpp

30 files changed, 1060 insertions, 181 deletions

diff --git a/ROMFS/px4fmu_common/init.d/4008_ardrone b/ROMFS/px4fmu_common/init.d/4008_ardrone
index 14786f210..e6007db0e 100644
--- a/ROMFS/px4fmu_common/init.d/4008_ardrone
+++ b/ROMFS/px4fmu_common/init.d/4008_ardrone
@@ -14,19 +14,20 @@ sh /etc/init.d/rc.mc_defaults
 if [ $DO_AUTOCONFIG == yes ]
 then
     # Set all params here, then disable autoconfig
-    param set MC_ROLL_P 5.0
-    param set MC_ROLLRATE_P 0.13
-    param set MC_ROLLRATE_I 0.0
-    param set MC_ROLLRATE_D 0.0
-    param set MC_PITCH_P 5.0
-    param set MC_PITCHRATE_P 0.13
-    param set MC_PITCHRATE_I 0.0
-    param set MC_PITCHRATE_D 0.0
-    param set MC_YAW_P 1.0
-    param set MC_YAWRATE_P 0.15
-    param set MC_YAWRATE_I 0.0
+    param set MC_ROLL_P 6.0
+    param set MC_ROLLRATE_P 0.14
+    param set MC_ROLLRATE_I 0.1
+    param set MC_ROLLRATE_D 0.002
+    param set MC_PITCH_P 6.0
+    param set MC_PITCHRATE_P 0.14
+    param set MC_PITCHRATE_I 0.1
+    param set MC_PITCHRATE_D 0.002
+    param set MC_YAW_P 2.0
+    param set MC_YAWRATE_P 0.2
+    param set MC_YAWRATE_I 0.2
     param set MC_YAWRATE_D 0.0
-    param set MC_YAW_FF 0.15
+    param set MC_YAW_FF 0.8
+    
     param set BAT_V_SCALING 0.00838095238
 fi
 
diff --git a/ROMFS/px4fmu_common/init.d/rc.mc_defaults b/ROMFS/px4fmu_common/init.d/rc.mc_defaults
index b6b0a5b4e..127e42164 100644
--- a/ROMFS/px4fmu_common/init.d/rc.mc_defaults
+++ b/ROMFS/px4fmu_common/init.d/rc.mc_defaults
@@ -37,10 +37,11 @@ then
 	param set MPC_LAND_SPEED 1.0
 
 	param set PE_VELNE_NOISE 0.5
-	param set PE_VELNE_NOISE 0.7
+	param set PE_VELD_NOISE 0.7
 	param set PE_POSNE_NOISE 0.5
 	param set PE_POSD_NOISE 1.0
 
+	param set NAV_ACCEPT_RAD 2.0
 fi
 
 set PWM_RATE 400
diff --git a/ROMFS/px4fmu_common/init.d/rcS b/ROMFS/px4fmu_common/init.d/rcS
index 8c413e087..6d06f897a 100644
--- a/ROMFS/px4fmu_common/init.d/rcS
+++ b/ROMFS/px4fmu_common/init.d/rcS
@@ -65,12 +65,12 @@ then
 	# Start CDC/ACM serial driver
 	#
 	sercon
-	
+
 	#
 	# Start the ORB (first app to start)
 	#
 	uorb start
-	
+
 	#
 	# Load parameters
 	#
@@ -79,7 +79,7 @@ then
 	then
 		set PARAM_FILE /fs/mtd_params
 	fi
-	
+
 	param select $PARAM_FILE
 	if param load
 	then
@@ -87,21 +87,25 @@ then
 	else
 		echo "[init] ERROR: Params loading failed: $PARAM_FILE"
 	fi
-	
+
 	#
 	# Start system state indicator
 	#
 	if rgbled start
 	then
-		echo "[init] Using external RGB Led"
+		echo "[init] RGB Led"
 	else
 		if blinkm start
 		then
-			echo "[init] Using blinkm"
+			echo "[init] BlinkM"
 			blinkm systemstate
 		fi
 	fi
-	
+
+	if pca8574 start
+	then
+	fi
+
 	#
 	# Set default values
 	#
@@ -122,7 +126,7 @@ then
 	set LOAD_DEFAULT_APPS yes
 	set GPS yes
 	set GPS_FAKE no
-	
+
 	#
 	# Set DO_AUTOCONFIG flag to use it in AUTOSTART scripts
 	#
@@ -132,7 +136,7 @@ then
 	else
 		set DO_AUTOCONFIG no
 	fi
-	
+
 	#
 	# Set USE_IO flag
 	#
@@ -142,7 +146,7 @@ then
 	else
 		set USE_IO no
 	fi
-		
+
 	#
 	# Set parameters and env variables for selected AUTOSTART
 	#
@@ -172,9 +176,9 @@ then
 		param set SYS_AUTOCONFIG 0
 		param save
 	fi
-	
+
 	set IO_PRESENT no
-	
+
 	if [ $USE_IO == yes ]
 	then
 		#
@@ -186,19 +190,19 @@ then
 		else
 			set IO_FILE /etc/extras/px4io-v1_default.bin
 		fi
-		
+
 		if px4io checkcrc $IO_FILE
 		then
 			echo "[init] PX4IO CRC OK"
 			echo "PX4IO CRC OK" >> $LOG_FILE
-	
+
 			set IO_PRESENT yes
 		else
 			echo "[init] Trying to update"
 			echo "PX4IO Trying to update" >> $LOG_FILE
-			
+
 			tone_alarm MLL32CP8MB
-			
+
 			if px4io forceupdate 14662 $IO_FILE
 			then
 				usleep 500000
@@ -207,7 +211,7 @@ then
 					echo "[init] PX4IO CRC OK, update successful"
 					echo "PX4IO CRC OK after updating" >> $LOG_FILE
 					tone_alarm MLL8CDE
-	
+
 					set IO_PRESENT yes
 				else
 					echo "[init] ERROR: PX4IO update failed"
@@ -220,14 +224,14 @@ then
 				tone_alarm $TUNE_OUT_ERROR
 			fi
 		fi
-		
+
 		if [ $IO_PRESENT == no ]
 		then
 			echo "[init] ERROR: PX4IO not found"
 			tone_alarm $TUNE_OUT_ERROR
 		fi
 	fi
-	
+
 	#
 	# Set default output if not set
 	#
@@ -246,7 +250,7 @@ then
 		# Need IO for output but it not present, disable output
 		set OUTPUT_MODE none
 		echo "[init] ERROR: PX4IO not found, disabling output"
-		
+
 		# Avoid using ttyS0 for MAVLink on FMUv1
 		if ver hwcmp PX4FMU_V1
 		then
@@ -270,17 +274,17 @@ then
 
 	# Try to get an USB console
 	nshterm /dev/ttyACM0 &
-	
+
 	#
 	# Start the Commander (needs to be this early for in-air-restarts)
 	#
 	commander start
-	
+
 	#
 	# Start primary output
 	#
 	set TTYS1_BUSY no
-	
+
 	# If OUTPUT_MODE == none then something is wrong with setup and we shouldn't try to enable output
 	if [ $OUTPUT_MODE != none ]
 	then
@@ -296,7 +300,7 @@ then
 				tone_alarm $TUNE_OUT_ERROR
 			fi
 		fi
-		
+
 		if [ $OUTPUT_MODE == fmu -o $OUTPUT_MODE == ardrone ]
 		then
 			echo "[init] Use FMU as primary output"
@@ -307,7 +311,7 @@ then
 				echo "[init] ERROR: FMU mode_$FMU_MODE start failed"
 				tone_alarm $TUNE_OUT_ERROR
 			fi
-			
+
 			if ver hwcmp PX4FMU_V1
 			then
 				if [ $FMU_MODE == pwm -o $FMU_MODE == gpio ]
@@ -320,7 +324,7 @@ then
 				fi
 			fi
 		fi
-		
+
 		if [ $OUTPUT_MODE == mkblctrl ]
 		then
 			echo "[init] Use MKBLCTRL as primary output"
@@ -333,7 +337,7 @@ then
 			then
 				set MKBLCTRL_ARG "-mkmode +"
 			fi
-			
+
 			if mkblctrl $MKBLCTRL_ARG
 			then
 				echo "[init] MKBLCTRL started"
@@ -341,9 +345,9 @@ then
 				echo "[init] ERROR: MKBLCTRL start failed"
 				tone_alarm $TUNE_OUT_ERROR
 			fi
-			
+
 		fi
-				
+
 		if [ $OUTPUT_MODE == hil ]
 		then
 			echo "[init] Use HIL as primary output"
@@ -355,7 +359,7 @@ then
 				tone_alarm $TUNE_OUT_ERROR
 			fi
 		fi
-		
+
 		#
 		# Start IO or FMU for RC PPM input if needed
 		#
@@ -382,7 +386,7 @@ then
 					echo "[init] ERROR: FMU mode_$FMU_MODE start failed"
 					tone_alarm $TUNE_OUT_ERROR
 				fi
-	
+
 				if ver hwcmp PX4FMU_V1
 				then
 					if [ $FMU_MODE == pwm -o $FMU_MODE == gpio ]
@@ -397,7 +401,7 @@ then
 			fi
 		fi
 	fi
-	
+
 	#
 	# MAVLink
 	#
@@ -418,7 +422,7 @@ then
 	fi
 
 	mavlink start $MAVLINK_FLAGS
-	
+
 	#
 	# Sensors, Logging, GPS
 	#
@@ -429,7 +433,7 @@ then
 		echo "[init] Start logging"
 		sh /etc/init.d/rc.logging
 	fi
-	
+
 	if [ $GPS == yes ]
 	then
 		echo "[init] Start GPS"
@@ -439,7 +443,7 @@ then
 			gps start -f
 		else
 			gps start
-		fi		
+		fi
 	fi
 
 	#
@@ -456,24 +460,24 @@ then
 	if [ $VEHICLE_TYPE == fw ]
 	then
 		echo "[init] Vehicle type: FIXED WING"
-		
+
 		if [ $MIXER == none ]
 		then
 			# Set default mixer for fixed wing if not defined
 			set MIXER FMU_AERT
 		fi
-		
+
 		if [ $MAV_TYPE == none ]
 		then
 			# Use MAV_TYPE = 1 (fixed wing) if not defined
 			set MAV_TYPE 1
 		fi
-		
+
 		param set MAV_TYPE $MAV_TYPE
-		
+
 		# Load mixer and configure outputs
 		sh /etc/init.d/rc.interface
-		
+
 		# Start standard fixedwing apps
 		if [ $LOAD_DEFAULT_APPS == yes ]
 		then
@@ -521,7 +525,7 @@ then
 				set MAV_TYPE 14
 			fi
 		fi
-		
+
 		# Still no MAV_TYPE found
 		if [ $MAV_TYPE == none ]
 		then
@@ -529,10 +533,10 @@ then
 		else
 			param set MAV_TYPE $MAV_TYPE
 		fi
-		
+
 		# Load mixer and configure outputs
 		sh /etc/init.d/rc.interface
-		
+
 		# Start standard multicopter apps
 		if [ $LOAD_DEFAULT_APPS == yes ]
 		then
diff --git a/ROMFS/px4fmu_common/mixers/README b/ROMFS/px4fmu_common/mixers/README
new file mode 100644
index 000000000..60311232e
--- /dev/null
+++ b/ROMFS/px4fmu_common/mixers/README
@@ -0,0 +1,154 @@
+PX4 mixer definitions
+=====================
+
+Files in this directory implement example mixers that can be used as a basis
+for customisation, or for general testing purposes.
+
+Mixer basics
+------------
+
+Mixers combine control values from various sources (control tasks, user inputs,
+etc.) and produce output values suitable for controlling actuators; servos,
+motors, switches and so on.
+
+An actuator derives its value from the combination of one or more control
+values. Each of the control values is scaled according to the actuator's
+configuration and then combined to produce the actuator value, which may then be
+further scaled to suit the specific output type.
+
+Internally, all scaling is performed using floating point values. Inputs and
+outputs are clamped to the range -1.0 to 1.0.
+
+control    control   control
+   |          |         |
+   v          v         v
+ scale      scale     scale
+   |          |         |
+   |          v         |
+   +-------> mix <------+
+              |
+            scale
+              |
+              v
+             out
+
+Scaling
+-------
+
+Basic scalers provide linear scaling of the input to the output.
+
+Each scaler allows the input value to be scaled independently for inputs
+greater/less than zero. An offset can be applied to the output, and lower and
+upper boundary constraints can be applied. Negative scaling factors cause the
+output to be inverted (negative input produces positive output).
+
+Scaler pseudocode:
+
+if (input < 0)
+    output = (input * NEGATIVE_SCALE) + OFFSET
+else
+    output = (input * POSITIVE_SCALE) + OFFSET
+
+if (output < LOWER_LIMIT)
+    output = LOWER_LIMIT
+if (output > UPPER_LIMIT)
+    output = UPPER_LIMIT
+
+Syntax
+------
+
+Mixer definitions are text files; lines beginning with a single capital letter
+followed by a colon are significant. All other lines are ignored, meaning that
+explanatory text can be freely mixed with the definitions.
+
+Each file may define more than one mixer; the allocation of mixers to actuators
+is specific to the device reading the mixer definition, and the number of
+actuator outputs generated by a mixer is specific to the mixer.
+
+A mixer begins with a line of the form
+
+	<tag>: <mixer arguments>
+
+The tag selects the mixer type; 'M' for a simple summing mixer, 'R' for a 
+multirotor mixer, etc.
+
+Null Mixer
+..........
+
+A null mixer consumes no controls and generates a single actuator output whose
+value is always zero.  Typically a null mixer is used as a placeholder in a
+collection of mixers in order to achieve a specific pattern of actuator outputs.
+
+The null mixer definition has the form:
+
+  Z:
+
+Simple Mixer
+............
+
+A simple mixer combines zero or more control inputs into a single actuator
+output.  Inputs are scaled, and the mixing function sums the result before
+applying an output scaler.
+
+A simple mixer definition begins with:
+
+  M: <control count>
+  O: <-ve scale> <+ve scale> <offset> <lower limit> <upper limit>
+
+If <control count> is zero, the sum is effectively zero and the mixer will
+output a fixed value that is <offset> constrained by <lower limit> and <upper
+limit>.
+
+The second line defines the output scaler with scaler parameters as discussed
+above. Whilst the calculations are performed as floating-point operations, the
+values stored in the definition file are scaled by a factor of 10000; i.e. an
+offset of -0.5 is encoded as -5000.
+
+The definition continues with <control count> entries describing the control
+inputs and their scaling, in the form:
+
+  S: <group> <index> <-ve scale> <+ve scale> <offset> <lower limit> <upper limit>
+
+The <group> value identifies the control group from which the scaler will read,
+and the <index> value an offset within that group.  These values are specific to
+the device reading the mixer definition.
+
+When used to mix vehicle controls, mixer group zero is the vehicle attitude
+control group, and index values zero through three are normally roll, pitch,
+yaw and thrust respectively.
+
+The remaining fields on the line configure the control scaler with parameters as
+discussed above. Whilst the calculations are performed as floating-point
+operations, the values stored in the definition file are scaled by a factor of
+10000; i.e. an offset of -0.5 is encoded as -5000.
+
+Multirotor Mixer
+................
+
+The multirotor mixer combines four control inputs (roll, pitch, yaw, thrust)
+into a set of actuator outputs intended to drive motor speed controllers.
+
+The mixer definition is a single line of the form:
+
+R: <geometry> <roll scale> <pitch scale> <yaw scale> <deadband>
+
+The supported geometries include:
+
+  4x - quadrotor in X configuration
+  4+ - quadrotor in + configuration
+  6x - hexcopter in X configuration
+  6+ - hexcopter in + configuration
+  8x - octocopter in X configuration
+  8+ - octocopter in + configuration
+  
+Each of the roll, pitch and yaw scale values determine scaling of the roll,
+pitch and yaw controls relative to the thrust control.  Whilst the calculations
+are performed as floating-point operations, the values stored in the definition
+file are scaled by a factor of 10000; i.e. an factor of 0.5 is encoded as 5000.
+
+Roll, pitch and yaw inputs are expected to range from -1.0 to 1.0, whilst the
+thrust input ranges from 0.0 to 1.0.  Output for each actuator is in the 
+range -1.0 to 1.0.
+
+In the case where an actuator saturates, all actuator values are rescaled so that 
+the saturating actuator is limited to 1.0.
\ No newline at end of file
diff --git a/makefiles/config_px4fmu-v2_default.mk b/makefiles/config_px4fmu-v2_default.mk
index d6e88859c..a68cc32f4 100644
--- a/makefiles/config_px4fmu-v2_default.mk
+++ b/makefiles/config_px4fmu-v2_default.mk
@@ -40,6 +40,7 @@ MODULES		+= drivers/meas_airspeed
 MODULES		+= drivers/frsky_telemetry
 MODULES		+= modules/sensors
 MODULES		+= drivers/mkblctrl
+MODULES		+= drivers/pca8574
 
 
 # Needs to be burned to the ground and re-written; for now,
diff --git a/makefiles/config_px4fmu-v2_test.mk b/makefiles/config_px4fmu-v2_test.mk
index 84274bf75..66b2157ed 100644
--- a/makefiles/config_px4fmu-v2_test.mk
+++ b/makefiles/config_px4fmu-v2_test.mk
@@ -24,6 +24,7 @@ MODULES		+= drivers/lsm303d
 MODULES		+= drivers/l3gd20
 MODULES		+= drivers/hmc5883
 MODULES		+= drivers/ms5611
+MODULES		+= drivers/pca8574
 MODULES		+= systemcmds/perf
 MODULES		+= systemcmds/reboot
 MODULES		+= systemcmds/tests
diff --git a/nuttx-configs/px4fmu-v1/nsh/defconfig b/nuttx-configs/px4fmu-v1/nsh/defconfig
index bc0c12067..f2c7d22bf 100644
--- a/nuttx-configs/px4fmu-v1/nsh/defconfig
+++ b/nuttx-configs/px4fmu-v1/nsh/defconfig
@@ -504,8 +504,8 @@ CONFIG_MTD_BYTE_WRITE=y
 #
 # USART1 Configuration
 #
-CONFIG_USART1_RXBUFSIZE=256
-CONFIG_USART1_TXBUFSIZE=128
+CONFIG_USART1_RXBUFSIZE=300
+CONFIG_USART1_TXBUFSIZE=300
 CONFIG_USART1_BAUD=57600
 CONFIG_USART1_BITS=8
 CONFIG_USART1_PARITY=0
@@ -528,8 +528,8 @@ CONFIG_USART2_OFLOWCONTROL=y
 #
 # UART5 Configuration
 #
-CONFIG_UART5_RXBUFSIZE=256
-CONFIG_UART5_TXBUFSIZE=128
+CONFIG_UART5_RXBUFSIZE=300
+CONFIG_UART5_TXBUFSIZE=300
 CONFIG_UART5_BAUD=57600
 CONFIG_UART5_BITS=8
 CONFIG_UART5_PARITY=0
diff --git a/nuttx-configs/px4fmu-v2/include/board.h b/nuttx-configs/px4fmu-v2/include/board.h
index 3bede8a1f..3b3c6fa70 100755
--- a/nuttx-configs/px4fmu-v2/include/board.h
+++ b/nuttx-configs/px4fmu-v2/include/board.h
@@ -268,6 +268,10 @@
 #define GPIO_SPI2_MOSI	(GPIO_SPI2_MOSI_1|GPIO_SPEED_50MHz)
 #define GPIO_SPI2_SCK	(GPIO_SPI2_SCK_2|GPIO_SPEED_50MHz)
 
+#define GPIO_SPI4_MISO	(GPIO_SPI4_MISO_1|GPIO_SPEED_50MHz)
+#define GPIO_SPI4_MOSI	(GPIO_SPI4_MOSI_1|GPIO_SPEED_50MHz)
+#define GPIO_SPI4_SCK	(GPIO_SPI4_SCK_1|GPIO_SPEED_50MHz)
+
 /************************************************************************************
  * Public Data
  ************************************************************************************/
diff --git a/nuttx-configs/px4fmu-v2/nsh/defconfig b/nuttx-configs/px4fmu-v2/nsh/defconfig
index a982040c6..7d5e6e9df 100644
--- a/nuttx-configs/px4fmu-v2/nsh/defconfig
+++ b/nuttx-configs/px4fmu-v2/nsh/defconfig
@@ -235,7 +235,7 @@ CONFIG_STM32_SDIO=y
 CONFIG_STM32_SPI1=y
 CONFIG_STM32_SPI2=y
 # CONFIG_STM32_SPI3 is not set
-# CONFIG_STM32_SPI4 is not set
+CONFIG_STM32_SPI4=y
 # CONFIG_STM32_SPI5 is not set
 # CONFIG_STM32_SPI6 is not set
 CONFIG_STM32_SYSCFG=y
diff --git a/src/drivers/boards/px4fmu-v1/board_config.h b/src/drivers/boards/px4fmu-v1/board_config.h
index 58273f2d2..c944007a5 100644
--- a/src/drivers/boards/px4fmu-v1/board_config.h
+++ b/src/drivers/boards/px4fmu-v1/board_config.h
@@ -86,6 +86,7 @@ __BEGIN_DECLS
 #define GPIO_SPI_CS_SDCARD	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_50MHz|GPIO_OUTPUT_SET|GPIO_PORTA|GPIO_PIN4)
 
 #define PX4_SPI_BUS_SENSORS	1
+#define PX4_SPI_BUS_EXT		2
 
 /*
  * Use these in place of the spi_dev_e enumeration to
@@ -98,7 +99,7 @@ __BEGIN_DECLS
 /*
  * Optional devices on IO's external port
  */
-#define PX4_SPIDEV_ACCEL_MAG 2
+#define PX4_SPIDEV_ACCEL_MAG	2
 
 /*
  * I2C busses
diff --git a/src/drivers/boards/px4fmu-v2/board_config.h b/src/drivers/boards/px4fmu-v2/board_config.h
index c2de1bfba..36eb7bec4 100644
--- a/src/drivers/boards/px4fmu-v2/board_config.h
+++ b/src/drivers/boards/px4fmu-v2/board_config.h
@@ -106,8 +106,11 @@ __BEGIN_DECLS
 #define GPIO_SPI_CS_BARO	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTD|GPIO_PIN7)
 #define GPIO_SPI_CS_FRAM	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTD|GPIO_PIN10)
 #define GPIO_SPI_CS_MPU		(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN2)
+#define GPIO_SPI_CS_EXT0	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_50MHz|GPIO_OUTPUT_SET|GPIO_PORTE|GPIO_PIN4)
+#define GPIO_SPI_CS_EXT1	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_50MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN14)
 
 #define PX4_SPI_BUS_SENSORS	1
+#define PX4_SPI_BUS_EXT		4
 
 /* Use these in place of the spi_dev_e enumeration to select a specific SPI device on SPI1 */
 #define PX4_SPIDEV_GYRO		1
@@ -115,6 +118,10 @@ __BEGIN_DECLS
 #define PX4_SPIDEV_BARO		3
 #define PX4_SPIDEV_MPU		4
 
+/* External bus */
+#define PX4_SPIDEV_EXT0		1
+#define PX4_SPIDEV_EXT1		2
+
 /* I2C busses */
 #define PX4_I2C_BUS_EXPANSION	1
 #define PX4_I2C_BUS_LED		2
diff --git a/src/drivers/boards/px4fmu-v2/px4fmu2_init.c b/src/drivers/boards/px4fmu-v2/px4fmu2_init.c
index 71414d62c..bf41bb1fe 100644
--- a/src/drivers/boards/px4fmu-v2/px4fmu2_init.c
+++ b/src/drivers/boards/px4fmu-v2/px4fmu2_init.c
@@ -192,6 +192,7 @@ stm32_boardinitialize(void)
 
 static struct spi_dev_s *spi1;
 static struct spi_dev_s *spi2;
+static struct spi_dev_s *spi4;
 static struct sdio_dev_s *sdio;
 
 #include <math.h>
@@ -305,6 +306,17 @@ __EXPORT int nsh_archinitialize(void)
 
 	message("[boot] Initialized SPI port 2 (RAMTRON FRAM)\n");
 
+	spi4 = up_spiinitialize(4);
+
+	/* Default SPI4 to 1MHz and de-assert the known chip selects. */
+	SPI_SETFREQUENCY(spi4, 10000000);
+	SPI_SETBITS(spi4, 8);
+	SPI_SETMODE(spi4, SPIDEV_MODE3);
+	SPI_SELECT(spi4, PX4_SPIDEV_EXT0, false);
+	SPI_SELECT(spi4, PX4_SPIDEV_EXT1, false);
+
+	message("[boot] Initialized SPI port 4\n");
+
 	#ifdef CONFIG_MMCSD
 	/* First, get an instance of the SDIO interface */
 
diff --git a/src/drivers/boards/px4fmu-v2/px4fmu_spi.c b/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
index c66c490a7..01dbd6e77 100644
--- a/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
+++ b/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
@@ -94,6 +94,13 @@ __EXPORT void weak_function stm32_spiinitialize(void)
 	stm32_configgpio(GPIO_SPI_CS_FRAM);
 	stm32_gpiowrite(GPIO_SPI_CS_FRAM, 1);
 #endif
+
+#ifdef CONFIG_STM32_SPI4
+	stm32_configgpio(GPIO_SPI_CS_EXT0);
+	stm32_configgpio(GPIO_SPI_CS_EXT1);
+	stm32_gpiowrite(GPIO_SPI_CS_EXT0, 1);
+	stm32_gpiowrite(GPIO_SPI_CS_EXT1, 1);
+#endif
 }
 
 __EXPORT void stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected)
@@ -157,3 +164,31 @@ __EXPORT uint8_t stm32_spi2status(FAR struct spi_dev_s *dev, enum spi_dev_e devi
 	return SPI_STATUS_PRESENT;
 }
 #endif
+
+__EXPORT void stm32_spi4select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected)
+{
+	/* SPI select is active low, so write !selected to select the device */
+
+	switch (devid) {
+	case PX4_SPIDEV_EXT0:
+		/* Making sure the other peripherals are not selected */
+		stm32_gpiowrite(GPIO_SPI_CS_EXT0, !selected);
+		stm32_gpiowrite(GPIO_SPI_CS_EXT1, 1);
+		break;
+
+	case PX4_SPIDEV_EXT1:
+		/* Making sure the other peripherals are not selected */
+		stm32_gpiowrite(GPIO_SPI_CS_EXT1, !selected);
+		stm32_gpiowrite(GPIO_SPI_CS_EXT0, 1);
+		break;
+
+	default:
+		break;
+
+	}
+}
+
+__EXPORT uint8_t stm32_spi4status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
+{
+	return SPI_STATUS_PRESENT;
+}
diff --git a/src/drivers/drv_io_expander.h b/src/drivers/drv_io_expander.h
new file mode 100644
index 000000000..106354377
--- /dev/null
+++ b/src/drivers/drv_io_expander.h
@@ -0,0 +1,71 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2014 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 drv_io_expander.h
+ *
+ * IO expander device API
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <sys/ioctl.h>
+
+/*
+ * ioctl() definitions
+ */
+
+#define _IOXIOCBASE		(0x2800)
+#define _IOXIOC(_n)		(_IOC(_IOXIOCBASE, _n))
+
+/** set a bitmask (non-blocking) */
+#define IOX_SET_MASK		_IOXIOC(1)
+
+/** get a bitmask (blocking) */
+#define IOX_GET_MASK		_IOXIOC(2)
+
+/** set device mode (non-blocking) */
+#define IOX_SET_MODE		_IOXIOC(3)
+
+/** set constant values (non-blocking) */
+#define IOX_SET_VALUE		_IOXIOC(4)
+
+/* ... to IOX_SET_VALUE + 8 */
+
+/* enum passed to RGBLED_SET_MODE ioctl()*/
+enum IOX_MODE {
+	IOX_MODE_OFF,
+	IOX_MODE_ON,
+	IOX_MODE_TEST_OUT
+};
diff --git a/src/drivers/gps/ubx.cpp b/src/drivers/gps/ubx.cpp
index 183b81ea9..6820fb73d 100644
--- a/src/drivers/gps/ubx.cpp
+++ b/src/drivers/gps/ubx.cpp
@@ -447,8 +447,8 @@ UBX::handle_message()
 					gps_bin_nav_sol_packet_t *packet = (gps_bin_nav_sol_packet_t *) _rx_buffer;
 
 					_gps_position->fix_type = packet->gpsFix;
-					_gps_position->s_variance_m_s = packet->sAcc;
-					_gps_position->p_variance_m = packet->pAcc;
+					_gps_position->s_variance_m_s = (float)packet->sAcc * 1e-2f; // from cm/s to m/s
+					_gps_position->p_variance_m = (float)packet->pAcc * 1e-2f; // from cm to m
 					_gps_position->timestamp_variance = hrt_absolute_time();
 
 					ret = 1;
diff --git a/src/drivers/lsm303d/lsm303d.cpp b/src/drivers/lsm303d/lsm303d.cpp
index 4ca8b5e42..8bf76dcc3 100644
--- a/src/drivers/lsm303d/lsm303d.cpp
+++ b/src/drivers/lsm303d/lsm303d.cpp
@@ -880,7 +880,7 @@ LSM303D::mag_read(struct file *filp, char *buffer, size_t buflen)
 
 	/* manual measurement */
 	_mag_reports->flush();
-	measure();
+	_mag->measure();
 
 	/* measurement will have generated a report, copy it out */
 	if (_mag_reports->get(mrb))
diff --git a/src/drivers/pca8574/module.mk b/src/drivers/pca8574/module.mk
new file mode 100644
index 000000000..825ee9bb7
--- /dev/null
+++ b/src/drivers/pca8574/module.mk
@@ -0,0 +1,6 @@
+#
+# PCA8574 driver for RGB LED
+#
+
+MODULE_COMMAND	 = pca8574
+SRCS		 = pca8574.cpp
diff --git a/src/drivers/pca8574/pca8574.cpp b/src/drivers/pca8574/pca8574.cpp
new file mode 100644
index 000000000..904ce18e8
--- /dev/null
+++ b/src/drivers/pca8574/pca8574.cpp
@@ -0,0 +1,554 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2012-2014 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 pca8574.cpp
+ *
+ * Driver for an 8 I/O controller (PC8574) connected via I2C.
+ *
+ * @author Lorenz Meier <lm@inf.ethz.ch>
+ * @author Julian Oes <joes@student.ethz.ch>
+ * @author Anton Babushkin <anton.babushkin@me.com>
+ */
+
+#include <nuttx/config.h>
+
+#include <drivers/device/i2c.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#include <nuttx/wqueue.h>
+
+#include <systemlib/perf_counter.h>
+#include <systemlib/err.h>
+#include <systemlib/systemlib.h>
+
+#include <board_config.h>
+
+#include <drivers/drv_io_expander.h>
+
+#define PCA8574_ONTIME 120
+#define PCA8574_OFFTIME 120
+#define PCA8574_DEVICE_PATH "/dev/pca8574"
+
+#define ADDR			0x20	///< I2C adress of PCA8574 (default, A0-A2 pulled to GND)
+
+class PCA8574 : public device::I2C
+{
+public:
+	PCA8574(int bus, int pca8574);
+	virtual ~PCA8574();
+
+
+	virtual int		init();
+	virtual int		probe();
+	virtual int		info();
+	virtual int		ioctl(struct file *filp, int cmd, unsigned long arg);
+	bool			is_running() { return _running; }
+
+private:
+	work_s			_work;
+
+	uint8_t			_values_out;
+	uint8_t			_values_in;
+	uint8_t			_blinking;
+	uint8_t			_blink_phase;
+
+	enum IOX_MODE		_mode;
+	bool			_running;
+	int			_led_interval;
+	bool			_should_run;
+	bool			_update_out;
+	int			_counter;
+
+	static void		led_trampoline(void *arg);
+	void			led();
+
+	int			send_led_enable(uint8_t arg);
+	int			send_led_values();
+
+	int			get(uint8_t &vals);
+};
+
+/* for now, we only support one PCA8574 */
+namespace
+{
+PCA8574 *g_pca8574;
+}
+
+void pca8574_usage();
+
+extern "C" __EXPORT int pca8574_main(int argc, char *argv[]);
+
+PCA8574::PCA8574(int bus, int pca8574) :
+	I2C("pca8574", PCA8574_DEVICE_PATH, bus, pca8574, 100000),
+	_values_out(0),
+	_values_in(0),
+	_blinking(0),
+	_blink_phase(0),
+	_mode(IOX_MODE_OFF),
+	_running(false),
+	_led_interval(80),
+	_should_run(false),
+	_update_out(false),
+	_counter(0)
+{
+	memset(&_work, 0, sizeof(_work));
+}
+
+PCA8574::~PCA8574()
+{
+}
+
+int
+PCA8574::init()
+{
+	int ret;
+	ret = I2C::init();
+
+	if (ret != OK) {
+		return ret;
+	}
+
+	return OK;
+}
+
+int
+PCA8574::probe()
+{
+	uint8_t val;
+	return get(val);
+}
+
+int
+PCA8574::info()
+{
+	int ret = OK;
+
+	return ret;
+}
+
+int
+PCA8574::ioctl(struct file *filp, int cmd, unsigned long arg)
+{
+	int ret = ENOTTY;
+
+	switch (cmd) {
+	case IOX_SET_VALUE ...(IOX_SET_VALUE + 8): {
+			// set the specified on / off state
+			uint8_t position = (1 << (cmd - IOX_SET_VALUE));
+			uint8_t prev = _values_out;
+
+			if (arg) {
+				_values_out |= position;
+
+			} else {
+				_values_out &= ~(position);
+			}
+
+			if (_values_out != prev) {
+				if (_values_out) {
+					_mode = IOX_MODE_ON;
+				}
+				send_led_values();
+			}
+
+			return OK;
+		}
+
+	case IOX_SET_MASK:
+		send_led_enable(arg);
+		return OK;
+
+	case IOX_GET_MASK: {
+			uint8_t val;
+			ret = get(val);
+
+			if (ret == OK) {
+				return val;
+
+			} else {
+				return -1;
+			}
+		}
+
+	case IOX_SET_MODE:
+
+		if (_mode != (IOX_MODE)arg) {
+
+			switch ((IOX_MODE)arg) {
+			case IOX_MODE_OFF:
+				_values_out = 0xFF;
+				break;
+
+			case IOX_MODE_ON:
+				_values_out = 0;
+				break;
+
+			case IOX_MODE_TEST_OUT:
+				break;
+
+			default:
+				return -1;
+			}
+
+			_mode = (IOX_MODE)arg;
+			send_led_values();
+		}
+
+		return OK;
+
+	default:
+		// see if the parent class can make any use of it
+		ret = CDev::ioctl(filp, cmd, arg);
+		break;
+	}
+
+	return ret;
+}
+
+
+void
+PCA8574::led_trampoline(void *arg)
+{
+	PCA8574 *rgbl = reinterpret_cast<PCA8574 *>(arg);
+
+	rgbl->led();
+}
+
+/**
+ * Main loop function
+ */
+void
+PCA8574::led()
+{
+	if (_mode == IOX_MODE_TEST_OUT) {
+
+		// we count only seven states
+		_counter &= 0xF;
+		_counter++;
+
+		for (int i = 0; i < 8; i++) {
+			if (i < _counter) {
+				_values_out |= (1 << i);
+
+			} else {
+				_values_out &= ~(1 << i);
+			}
+		}
+
+		_update_out = true;
+		_should_run = true;
+	} else if (_mode == IOX_MODE_OFF) {
+		_update_out = true;
+		_should_run = false;
+	} else {
+
+		// Any of the normal modes
+		if (_blinking > 0) {
+			/* we need to be running to blink */
+			_should_run = true;
+		} else {
+			_should_run = false;
+		}
+	}
+
+	if (_update_out) {
+		uint8_t msg;
+
+		if (_blinking) {
+			msg = (_values_out & _blinking & _blink_phase);
+
+			// wipe out all positions that are marked as blinking
+			msg &= ~(_blinking);
+
+			// fill blink positions
+			msg |= ((_blink_phase) ? _blinking : 0);
+
+			_blink_phase = !_blink_phase;
+		} else {
+			msg = _values_out;
+		}
+
+		int ret = transfer(&msg, sizeof(msg), nullptr, 0);
+
+		if (!ret) {
+			_update_out = false;
+		}
+	}
+
+	// check if any activity remains, else stp
+	if (!_should_run) {
+		_running = false;
+		return;
+	}
+
+	// re-queue ourselves to run again later
+	_running = true;
+	work_queue(LPWORK, &_work, (worker_t)&PCA8574::led_trampoline, this, _led_interval);
+}
+
+/**
+ * Sent ENABLE flag to LED driver
+ */
+int
+PCA8574::send_led_enable(uint8_t arg)
+{
+
+	int ret = transfer(&arg, sizeof(arg), nullptr, 0);
+
+	return ret;
+}
+
+/**
+ * Send 8 outputs
+ */
+int
+PCA8574::send_led_values()
+{
+	_update_out = true;
+
+	// if not active, kick it
+	if (!_running) {
+		_running = true;
+		work_queue(LPWORK, &_work, (worker_t)&PCA8574::led_trampoline, this, 1);
+	}
+
+	return 0;
+}
+
+int
+PCA8574::get(uint8_t &vals)
+{
+	uint8_t result;
+	int ret;
+
+	ret = transfer(nullptr, 0, &result, 1);
+
+	if (ret == OK) {
+		_values_in = result;
+		vals = result;
+	}
+
+	return ret;
+}
+
+void
+pca8574_usage()
+{
+	warnx("missing command: try 'start', 'test', 'info', 'off', 'stop', 'val 0 1'");
+	warnx("options:");
+	warnx("    -b i2cbus (%d)", PX4_I2C_BUS_LED);
+	warnx("    -a addr (0x%x)", ADDR);
+}
+
+int
+pca8574_main(int argc, char *argv[])
+{
+	int i2cdevice = -1;
+	int pca8574adr = ADDR; // 7bit
+
+	int ch;
+
+	// jump over start/off/etc and look at options first
+	while ((ch = getopt(argc, argv, "a:b:")) != EOF) {
+		switch (ch) {
+		case 'a':
+			pca8574adr = strtol(optarg, NULL, 0);
+			break;
+
+		case 'b':
+			i2cdevice = strtol(optarg, NULL, 0);
+			break;
+
+		default:
+			pca8574_usage();
+			exit(0);
+		}
+	}
+
+	if (optind >= argc) {
+		pca8574_usage();
+		exit(1);
+	}
+
+	const char *verb = argv[optind];
+
+	int fd;
+	int ret;
+
+	if (!strcmp(verb, "start")) {
+		if (g_pca8574 != nullptr) {
+			errx(1, "already started");
+		}
+
+		if (i2cdevice == -1) {
+			// try the external bus first
+			i2cdevice = PX4_I2C_BUS_EXPANSION;
+			g_pca8574 = new PCA8574(PX4_I2C_BUS_EXPANSION, pca8574adr);
+
+			if (g_pca8574 != nullptr && OK != g_pca8574->init()) {
+				delete g_pca8574;
+				g_pca8574 = nullptr;
+			}
+
+			if (g_pca8574 == nullptr) {
+				// fall back to default bus
+				if (PX4_I2C_BUS_LED == PX4_I2C_BUS_EXPANSION) {
+					errx(1, "init failed");
+				}
+
+				i2cdevice = PX4_I2C_BUS_LED;
+			}
+		}
+
+		if (g_pca8574 == nullptr) {
+			g_pca8574 = new PCA8574(i2cdevice, pca8574adr);
+
+			if (g_pca8574 == nullptr) {
+				errx(1, "new failed");
+			}
+
+			if (OK != g_pca8574->init()) {
+				delete g_pca8574;
+				g_pca8574 = nullptr;
+				errx(1, "init failed");
+			}
+		}
+
+		exit(0);
+	}
+
+	// need the driver past this point
+	if (g_pca8574 == nullptr) {
+		warnx("not started, run pca8574 start");
+		exit(1);
+	}
+
+	if (!strcmp(verb, "test")) {
+		fd = open(PCA8574_DEVICE_PATH, 0);
+
+		if (fd == -1) {
+			errx(1, "Unable to open " PCA8574_DEVICE_PATH);
+		}
+
+		ret = ioctl(fd, IOX_SET_MODE, (unsigned long)IOX_MODE_TEST_OUT);
+
+		close(fd);
+		exit(ret);
+	}
+
+	if (!strcmp(verb, "info")) {
+		g_pca8574->info();
+		exit(0);
+	}
+
+	if (!strcmp(verb, "off")) {
+		fd = open(PCA8574_DEVICE_PATH, 0);
+
+		if (fd < 0) {
+			errx(1, "Unable to open " PCA8574_DEVICE_PATH);
+		}
+
+		ret = ioctl(fd, IOX_SET_MODE, (unsigned long)IOX_MODE_OFF);
+		close(fd);
+		exit(ret);
+	}
+
+	if (!strcmp(verb, "stop")) {
+		fd = open(PCA8574_DEVICE_PATH, 0);
+
+		if (fd == -1) {
+			errx(1, "Unable to open " PCA8574_DEVICE_PATH);
+		}
+
+		ret = ioctl(fd, IOX_SET_MODE, (unsigned long)IOX_MODE_OFF);
+		close(fd);
+
+		// wait until we're not running any more
+		for (unsigned i = 0; i < 15; i++) {
+			if (!g_pca8574->is_running()) {
+				break;
+			}
+
+			usleep(50000);
+			printf(".");
+			fflush(stdout);
+		}
+		printf("\n");
+		fflush(stdout);
+
+		if (!g_pca8574->is_running()) {
+			delete g_pca8574;
+			g_pca8574 = nullptr;
+			exit(0);
+		} else {
+			warnx("stop failed.");
+			exit(1);
+		}
+	}
+
+	if (!strcmp(verb, "val")) {
+		if (argc < 4) {
+			errx(1, "Usage: pca8574 val <channel> <0 or 1>");
+		}
+
+		fd = open(PCA8574_DEVICE_PATH, 0);
+
+		if (fd == -1) {
+			errx(1, "Unable to open " PCA8574_DEVICE_PATH);
+		}
+
+		unsigned channel = strtol(argv[2], NULL, 0);
+		unsigned val = strtol(argv[3], NULL, 0);
+
+		if (channel < 8) {
+			ret = ioctl(fd, (IOX_SET_VALUE + channel), val);
+		} else {
+			ret = -1;
+		}
+		close(fd);
+		exit(ret);
+	}
+
+	pca8574_usage();
+	exit(0);
+}
diff --git a/src/modules/commander/commander.cpp b/src/modules/commander/commander.cpp
index 5638bc09f..d7a95b0d6 100644
--- a/src/modules/commander/commander.cpp
+++ b/src/modules/commander/commander.cpp
@@ -1344,7 +1344,7 @@ int commander_thread_main(int argc, char *argv[])
 				home.z = local_position.z;
 
 				warnx("home: lat = %.7f, lon = %.7f, alt = %.2f ", home.lat, home.lon, (double)home.alt);
-				mavlink_log_info(mavlink_fd, "#audio: home: %.7f, %.7f, %.2f", home.lat, home.lon, (double)home.alt);
+				mavlink_log_info(mavlink_fd, "home: %.7f, %.7f, %.2f", home.lat, home.lon, (double)home.alt);
 
 				/* announce new home position */
 				if (home_pub > 0) {
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index 48f91481d..de9071245 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -105,7 +105,8 @@ static struct file_operations fops;
  */
 extern "C" __EXPORT int mavlink_main(int argc, char *argv[]);
 
-static uint64_t last_write_times[6] = {0};
+static uint64_t last_write_success_times[6] = {0};
+static uint64_t last_write_try_times[6] = {0};
 
 /*
  * Internal function to send the bytes through the right serial port
@@ -166,38 +167,40 @@ mavlink_send_uart_bytes(mavlink_channel_t channel, const uint8_t *ch, int length
 	if (instance->get_flow_control_enabled()
 		&& ioctl(uart, FIONWRITE, (unsigned long)&buf_free) == 0) {
 
-		if (buf_free == 0) {
-
-			if (last_write_times[(unsigned)channel] != 0 &&
-				hrt_elapsed_time(&last_write_times[(unsigned)channel]) > 500 * 1000UL) {
-
-				warnx("DISABLING HARDWARE FLOW CONTROL");
-				instance->enable_flow_control(false);
-			}
-
-		} else {
-
-			/* apparently there is space left, although we might be
-			 * partially overflooding the buffer already */
-			last_write_times[(unsigned)channel] = hrt_absolute_time();
+		/* Disable hardware flow control:
+		 * if no successful write since a defined time
+		 * and if the last try was not the last successful write
+		 */
+		if (last_write_try_times[(unsigned)channel] != 0 &&
+			hrt_elapsed_time(&last_write_success_times[(unsigned)channel]) > 500 * 1000UL &&
+			last_write_success_times[(unsigned)channel] !=
+			last_write_try_times[(unsigned)channel])
+		{
+			warnx("DISABLING HARDWARE FLOW CONTROL");
+			instance->enable_flow_control(false);
 		}
+
 	}
 
 	/* If the wait until transmit flag is on, only transmit after we've received messages.
 	   Otherwise, transmit all the time. */
 	if (instance->should_transmit()) {
+		last_write_try_times[(unsigned)channel] = hrt_absolute_time();
 
 		/* check if there is space in the buffer, let it overflow else */
 		if (!ioctl(uart, FIONWRITE, (unsigned long)&buf_free)) {
 
-			if (desired > buf_free) {
-				desired = buf_free;
+			if (buf_free < desired) {
+				/* we don't want to send anything just in half, so return */
+				return;
 			}
 		}
 
 		ssize_t ret = write(uart, ch, desired);
 		if (ret != desired) {
 			warnx("TX FAIL");
+		} else {
+			last_write_success_times[(unsigned)channel] = last_write_try_times[(unsigned)channel];
 		}
 	}
 
@@ -222,6 +225,8 @@ Mavlink::Mavlink() :
 	_subscriptions(nullptr),
 	_streams(nullptr),
 	_mission_pub(-1),
+	_mode(MAVLINK_MODE_NORMAL),
+	_total_counter(0),
 	_verbose(false),
 	_forwarding_on(false),
 	_passing_on(false),
@@ -886,7 +891,7 @@ int Mavlink::map_mavlink_mission_item_to_mission_item(const mavlink_mission_item
 
 	switch (mavlink_mission_item->command) {
 	case MAV_CMD_NAV_TAKEOFF:
-		mission_item->pitch_min = mavlink_mission_item->param2;
+		mission_item->pitch_min = mavlink_mission_item->param1;
 		break;
 	case MAV_CMD_DO_JUMP:
 		mission_item->do_jump_mission_index = mavlink_mission_item->param1;
@@ -894,6 +899,7 @@ int Mavlink::map_mavlink_mission_item_to_mission_item(const mavlink_mission_item
 		break;
 	default:
 		mission_item->acceptance_radius = mavlink_mission_item->param2;
+		mission_item->time_inside = mavlink_mission_item->param1;
 		break;
 	}
 
@@ -902,7 +908,6 @@ int Mavlink::map_mavlink_mission_item_to_mission_item(const mavlink_mission_item
 	mission_item->loiter_direction = (mavlink_mission_item->param3 > 0) ? 1 : -1; /* 1 if positive CW, -1 if negative CCW */
 	mission_item->nav_cmd = (NAV_CMD)mavlink_mission_item->command;
 
-	mission_item->time_inside = mavlink_mission_item->param1;
 	mission_item->autocontinue = mavlink_mission_item->autocontinue;
 	// mission_item->index = mavlink_mission_item->seq;
 	mission_item->origin = ORIGIN_MAVLINK;
@@ -924,7 +929,7 @@ int Mavlink::map_mission_item_to_mavlink_mission_item(const struct mission_item_
 
 	switch (mission_item->nav_cmd) {
 	case NAV_CMD_TAKEOFF:
-		mavlink_mission_item->param2 = mission_item->pitch_min;
+		mavlink_mission_item->param1 = mission_item->pitch_min;
 		break;
 
 	case NAV_CMD_DO_JUMP:
@@ -934,6 +939,7 @@ int Mavlink::map_mission_item_to_mavlink_mission_item(const struct mission_item_
 
 	default:
 		mavlink_mission_item->param2 = mission_item->acceptance_radius;
+		mavlink_mission_item->param1 = mission_item->time_inside;
 		break;
 	}
 
@@ -944,7 +950,6 @@ int Mavlink::map_mission_item_to_mavlink_mission_item(const struct mission_item_
 	mavlink_mission_item->param4 = mission_item->yaw * M_RAD_TO_DEG_F;
 	mavlink_mission_item->param3 = mission_item->loiter_radius * (float)mission_item->loiter_direction;
 	mavlink_mission_item->command = mission_item->nav_cmd;
-	mavlink_mission_item->param1 = mission_item->time_inside;
 	mavlink_mission_item->autocontinue = mission_item->autocontinue;
 	// mavlink_mission_item->seq = mission_item->index;
 
diff --git a/src/modules/mavlink/mavlink_messages.cpp b/src/modules/mavlink/mavlink_messages.cpp
index 31c0c8f79..d1b943eab 100644
--- a/src/modules/mavlink/mavlink_messages.cpp
+++ b/src/modules/mavlink/mavlink_messages.cpp
@@ -295,7 +295,7 @@ protected:
 						status->onboard_control_sensors_health,
 						status->load * 1000.0f,
 						status->battery_voltage * 1000.0f,
-						status->battery_current * 1000.0f,
+						status->battery_current * 100.0f,
 						status->battery_remaining * 100.0f,
 						status->drop_rate_comm,
 						status->errors_comm,
diff --git a/src/modules/navigator/mission_feasibility_checker.cpp b/src/modules/navigator/mission_feasibility_checker.cpp
index 2f45f2267..e1a6854b2 100644
--- a/src/modules/navigator/mission_feasibility_checker.cpp
+++ b/src/modules/navigator/mission_feasibility_checker.cpp
@@ -63,7 +63,7 @@ MissionFeasibilityChecker::MissionFeasibilityChecker() : _mavlink_fd(-1), _capab
 }
 
 
-bool MissionFeasibilityChecker::checkMissionFeasible(bool isRotarywing, dm_item_t dm_current, size_t nMissionItems, Geofence &geofence)
+bool MissionFeasibilityChecker::checkMissionFeasible(bool isRotarywing, dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt)
 {
 	/* Init if not done yet */
 	init();
@@ -76,24 +76,24 @@ bool MissionFeasibilityChecker::checkMissionFeasible(bool isRotarywing, dm_item_
 
 
 	if (isRotarywing)
-		return checkMissionFeasibleRotarywing(dm_current, nMissionItems, geofence);
+		return checkMissionFeasibleRotarywing(dm_current, nMissionItems, geofence, home_alt);
 	else
-		return checkMissionFeasibleFixedwing(dm_current, nMissionItems, geofence);
+		return checkMissionFeasibleFixedwing(dm_current, nMissionItems, geofence, home_alt);
 }
 
-bool MissionFeasibilityChecker::checkMissionFeasibleRotarywing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence)
+bool MissionFeasibilityChecker::checkMissionFeasibleRotarywing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt)
 {
 
-	return checkGeofence(dm_current, nMissionItems, geofence);
+	return  (checkGeofence(dm_current, nMissionItems, geofence) && checkHomePositionAltitude(dm_current, nMissionItems, home_alt));
 }
 
-bool MissionFeasibilityChecker::checkMissionFeasibleFixedwing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence)
+bool MissionFeasibilityChecker::checkMissionFeasibleFixedwing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt)
 {
 	/* Update fixed wing navigation capabilites */
 	updateNavigationCapabilities();
 //	warnx("_nav_caps.landing_slope_angle_rad %.4f, _nav_caps.landing_horizontal_slope_displacement %.4f", _nav_caps.landing_slope_angle_rad, _nav_caps.landing_horizontal_slope_displacement);
 
-	return (checkFixedWingLanding(dm_current, nMissionItems) && checkGeofence(dm_current, nMissionItems, geofence));
+	return (checkFixedWingLanding(dm_current, nMissionItems) && checkGeofence(dm_current, nMissionItems, geofence) && checkHomePositionAltitude(dm_current, nMissionItems, home_alt));
 }
 
 bool MissionFeasibilityChecker::checkGeofence(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence)
@@ -109,7 +109,7 @@ bool MissionFeasibilityChecker::checkGeofence(dm_item_t dm_current, size_t nMiss
 				return false;
 			}
 
-			if (!geofence.inside(missionitem.lat, missionitem.lon, missionitem.altitude)) { //xxx: handle relative altitude
+			if (!geofence.inside(missionitem.lat, missionitem.lon, missionitem.altitude)) {
 				mavlink_log_info(_mavlink_fd, "#audio: Geofence violation waypoint %d", i);
 				return false;
 			}
@@ -119,6 +119,36 @@ bool MissionFeasibilityChecker::checkGeofence(dm_item_t dm_current, size_t nMiss
 	return true;
 }
 
+bool MissionFeasibilityChecker::checkHomePositionAltitude(dm_item_t dm_current, size_t nMissionItems, float home_alt, bool throw_error)
+{
+	/* Check if all all waypoints are above the home altitude, only return false if bool throw_error = true */
+	for (size_t i = 0; i < nMissionItems; i++) {
+		static struct mission_item_s missionitem;
+		const ssize_t len = sizeof(struct mission_item_s);
+
+		if (dm_read(dm_current, i, &missionitem, len) != len) {
+			/* not supposed to happen unless the datamanager can't access the SD card, etc. */
+			if (throw_error) {
+				return false;
+			} else	{
+				return true;
+			}
+		}
+
+		if (home_alt > missionitem.altitude) {
+			if (throw_error) {
+				mavlink_log_info(_mavlink_fd, "Waypoint %d below home", i);
+				return false;
+			} else	{
+				mavlink_log_info(_mavlink_fd, "#audio: warning waypoint %d below home", i);
+				return true;
+			}
+		}
+	}
+
+	return true;
+}
+
 bool MissionFeasibilityChecker::checkFixedWingLanding(dm_item_t dm_current, size_t nMissionItems)
 {
 	/* Go through all mission items and search for a landing waypoint
diff --git a/src/modules/navigator/mission_feasibility_checker.h b/src/modules/navigator/mission_feasibility_checker.h
index f98e28462..96c9209d3 100644
--- a/src/modules/navigator/mission_feasibility_checker.h
+++ b/src/modules/navigator/mission_feasibility_checker.h
@@ -61,14 +61,15 @@ private:
 
 	/* Checks for all airframes */
 	bool checkGeofence(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence);
+	bool checkHomePositionAltitude(dm_item_t dm_current, size_t nMissionItems, float home_alt, bool throw_error = false);
 
 	/* Checks specific to fixedwing airframes */
-	bool checkMissionFeasibleFixedwing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence);
+	bool checkMissionFeasibleFixedwing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt);
 	bool checkFixedWingLanding(dm_item_t dm_current, size_t nMissionItems);
 	void updateNavigationCapabilities();
 
 	/* Checks specific to rotarywing airframes */
-	bool checkMissionFeasibleRotarywing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence);
+	bool checkMissionFeasibleRotarywing(dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt);
 public:
 
 	MissionFeasibilityChecker();
@@ -77,7 +78,7 @@ public:
 	/*
 	 * Returns true if mission is feasible and false otherwise
 	 */
-	bool checkMissionFeasible(bool isRotarywing, dm_item_t dm_current, size_t nMissionItems, Geofence &geofence);
+	bool checkMissionFeasible(bool isRotarywing, dm_item_t dm_current, size_t nMissionItems, Geofence &geofence, float home_alt);
 
 };
 
diff --git a/src/modules/navigator/navigator_main.cpp b/src/modules/navigator/navigator_main.cpp
index b991ffc8c..f91032196 100644
--- a/src/modules/navigator/navigator_main.cpp
+++ b/src/modules/navigator/navigator_main.cpp
@@ -674,11 +674,10 @@ Navigator::check_mission_item_reached()
 		return _vstatus.condition_landed;
 	}
 
-	/* TODO: count turns */
-	// if ((_mission_item.nav_cmd == NAV_CMD_LOITER_TURN_COUNT ||
-	//      _mission_item.nav_cmd == NAV_CMD_LOITER_TIME_LIMIT ||
-	//      _mission_item.nav_cmd == NAV_CMD_LOITER_UNLIMITED) &&
-	//     _mission_item.loiter_radius > 0.01f) {
+	/* XXX TODO count turns */
+	if ((_mission_item.nav_cmd == NAV_CMD_LOITER_TURN_COUNT ||
+	     _mission_item.nav_cmd == NAV_CMD_LOITER_UNLIMITED) &&
+	    _mission_item.loiter_radius > 0.01f) {
 
 	// 	return false;
 	// }
@@ -695,24 +694,26 @@ Navigator::check_mission_item_reached()
 			acceptance_radius = _parameters.acceptance_radius;
 		}
 
-		float dist = -1.0f;
-		float dist_xy = -1.0f;
-		float dist_z = -1.0f;
-
-		float altitude_amsl = _mission_item.altitude_is_relative
-					? _mission_item.altitude + _home_pos.alt : _mission_item.altitude;
-
-		dist = get_distance_to_point_global_wgs84(_mission_item.lat, _mission_item.lon, altitude_amsl,
-				_global_pos.lat, _global_pos.lon, _global_pos.alt,
-				&dist_xy, &dist_z);
-
-		if (_mission_item.nav_cmd == NAV_CMD_TAKEOFF) {
-
+		if (_do_takeoff) {
 			/* require only altitude for takeoff */
-			if (_global_pos.alt > altitude_amsl - acceptance_radius) {
+			if (_global_pos.alt > _pos_sp_triplet.current.alt - acceptance_radius) {
 				_waypoint_position_reached = true;
 			}
 		} else {
+			float dist = -1.0f;
+			float dist_xy = -1.0f;
+			float dist_z = -1.0f;
+
+			/* calculate AMSL altitude for this waypoint */
+			float wp_alt_amsl = _mission_item.altitude;
+
+			if (_mission_item.altitude_is_relative)
+				wp_alt_amsl += _home_pos.alt;
+
+			dist = get_distance_to_point_global_wgs84(_mission_item.lat, _mission_item.lon, wp_alt_amsl,
+					(double)_global_pos.lat, (double)_global_pos.lon, _global_pos.alt,
+					&dist_xy, &dist_z);
+
 			if (dist >= 0.0f && dist <= acceptance_radius) {
 				_waypoint_position_reached = true;
 			}
@@ -765,7 +766,6 @@ Navigator::reset_reached()
 	_waypoint_yaw_reached = false;
 
 }
-#endif
 void
 Navigator::publish_position_setpoint_triplet()
 {
diff --git a/src/modules/position_estimator_inav/inertial_filter.c b/src/modules/position_estimator_inav/inertial_filter.c
index 2f1b3c014..a36a4688d 100644
--- a/src/modules/position_estimator_inav/inertial_filter.c
+++ b/src/modules/position_estimator_inav/inertial_filter.c
@@ -9,15 +9,18 @@
 
 #include "inertial_filter.h"
 
-void inertial_filter_predict(float dt, float x[3])
+void inertial_filter_predict(float dt, float x[2], float acc)
 {
 	if (isfinite(dt)) {
-		x[0] += x[1] * dt + x[2] * dt * dt / 2.0f;
-		x[1] += x[2] * dt;
+		if (!isfinite(acc)) {
+			acc = 0.0f;
+		}
+		x[0] += x[1] * dt + acc * dt * dt / 2.0f;
+		x[1] += acc * dt;
 	}
 }
 
-void inertial_filter_correct(float e, float dt, float x[3], int i, float w)
+void inertial_filter_correct(float e, float dt, float x[2], int i, float w)
 {
 	if (isfinite(e) && isfinite(w) && isfinite(dt)) {
 		float ewdt = e * w * dt;
@@ -25,10 +28,6 @@ void inertial_filter_correct(float e, float dt, float x[3], int i, float w)
 
 		if (i == 0) {
 			x[1] += w * ewdt;
-			x[2] += w * w * ewdt / 3.0;
-
-		} else if (i == 1) {
-			x[2] += w * ewdt;
 		}
 	}
 }
diff --git a/src/modules/position_estimator_inav/inertial_filter.h b/src/modules/position_estimator_inav/inertial_filter.h
index 761c17097..cdeb4cfc6 100644
--- a/src/modules/position_estimator_inav/inertial_filter.h
+++ b/src/modules/position_estimator_inav/inertial_filter.h
@@ -8,6 +8,6 @@
 #include <stdbool.h>
 #include <drivers/drv_hrt.h>
 
-void inertial_filter_predict(float dt, float x[3]);
+void inertial_filter_predict(float dt, float x[3], float acc);
 
 void inertial_filter_correct(float e, float dt, float x[3], int i, float w);
diff --git a/src/modules/position_estimator_inav/position_estimator_inav_main.c b/src/modules/position_estimator_inav/position_estimator_inav_main.c
index 4260623a3..62845494e 100644
--- a/src/modules/position_estimator_inav/position_estimator_inav_main.c
+++ b/src/modules/position_estimator_inav/position_estimator_inav_main.c
@@ -168,15 +168,15 @@ int position_estimator_inav_main(int argc, char *argv[])
 	exit(1);
 }
 
-void write_debug_log(const char *msg, float dt, float x_est[3], float y_est[3], float z_est[3], float x_est_prev[3], float y_est_prev[3], float z_est_prev[3], float corr_acc[3], float corr_gps[3][2], float w_xy_gps_p, float w_xy_gps_v)
+void write_debug_log(const char *msg, float dt, float x_est[2], float y_est[2], float z_est[2], float x_est_prev[2], float y_est_prev[2], float z_est_prev[2], float acc[3], float corr_gps[3][2], float w_xy_gps_p, float w_xy_gps_v)
 {
 	FILE *f = fopen("/fs/microsd/inav.log", "a");
 
 	if (f) {
 		char *s = malloc(256);
-		unsigned n = snprintf(s, 256, "%llu %s\n\tdt=%.5f x_est=[%.5f %.5f %.5f] y_est=[%.5f %.5f %.5f] z_est=[%.5f %.5f %.5f] x_est_prev=[%.5f %.5f %.5f] y_est_prev=[%.5f %.5f %.5f] z_est_prev=[%.5f %.5f %.5f]\n", hrt_absolute_time(), msg, dt, x_est[0], x_est[1], x_est[2], y_est[0], y_est[1], y_est[2], z_est[0], z_est[1], z_est[2], x_est_prev[0], x_est_prev[1], x_est_prev[2], y_est_prev[0], y_est_prev[1], y_est_prev[2], z_est_prev[0], z_est_prev[1], z_est_prev[2]);
+		unsigned n = snprintf(s, 256, "%llu %s\n\tdt=%.5f x_est=[%.5f %.5f] y_est=[%.5f %.5f] z_est=[%.5f %.5f] x_est_prev=[%.5f %.5f] y_est_prev=[%.5f %.5f] z_est_prev=[%.5f %.5f]\n", hrt_absolute_time(), msg, dt, x_est[0], x_est[1], y_est[0], y_est[1], z_est[0], z_est[1], x_est_prev[0], x_est_prev[1], y_est_prev[0], y_est_prev[1], z_est_prev[0], z_est_prev[1]);
 		fwrite(s, 1, n, f);
-		n = snprintf(s, 256, "\tacc_corr=[%.5f %.5f %.5f] gps_pos_corr=[%.5f %.5f %.5f] gps_vel_corr=[%.5f %.5f %.5f] w_xy_gps_p=%.5f w_xy_gps_v=%.5f\n", corr_acc[0], corr_acc[1], corr_acc[2], corr_gps[0][0], corr_gps[1][0], corr_gps[2][0], corr_gps[0][1], corr_gps[1][1], corr_gps[2][1], w_xy_gps_p, w_xy_gps_v);
+		n = snprintf(s, 256, "\tacc=[%.5f %.5f %.5f] gps_pos_corr=[%.5f %.5f %.5f] gps_vel_corr=[%.5f %.5f %.5f] w_xy_gps_p=%.5f w_xy_gps_v=%.5f\n", acc[0], acc[1], acc[2], corr_gps[0][0], corr_gps[1][0], corr_gps[2][0], corr_gps[0][1], corr_gps[1][1], corr_gps[2][1], w_xy_gps_p, w_xy_gps_v);
 		fwrite(s, 1, n, f);
 		free(s);
 	}
@@ -195,14 +195,14 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 	mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);
 	mavlink_log_info(mavlink_fd, "[inav] started");
 
-	float x_est[3] = { 0.0f, 0.0f, 0.0f };
-	float y_est[3] = { 0.0f, 0.0f, 0.0f };
-	float z_est[3] = { 0.0f, 0.0f, 0.0f };
+	float x_est[2] = { 0.0f, 0.0f };	// pos, vel
+	float y_est[2] = { 0.0f, 0.0f };	// pos, vel
+	float z_est[2] = { 0.0f, 0.0f };	// pos, vel
 
 	float eph = 1.0;
 	float epv = 1.0;
 
-	float x_est_prev[3], y_est_prev[3], z_est_prev[3];
+	float x_est_prev[2], y_est_prev[2], z_est_prev[2];
 	memset(x_est_prev, 0, sizeof(x_est_prev));
 	memset(y_est_prev, 0, sizeof(y_est_prev));
 	memset(z_est_prev, 0, sizeof(z_est_prev));
@@ -241,7 +241,7 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 	float accel_NED[3] = { 0.0f, 0.0f, -CONSTANTS_ONE_G };
 
 	/* store error when sensor updates, but correct on each time step to avoid jumps in estimated value */
-	float corr_acc[] = { 0.0f, 0.0f, 0.0f };	// N E D
+	float acc[] = { 0.0f, 0.0f, 0.0f };	// N E D
 	float acc_bias[] = { 0.0f, 0.0f, 0.0f };	// body frame
 	float corr_baro = 0.0f;		// D
 	float corr_gps[3][2] = {
@@ -341,8 +341,10 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 
 					/* mean calculation over several measurements */
 					if (baro_init_cnt < baro_init_num) {
-						baro_offset += sensor.baro_alt_meter;
-						baro_init_cnt++;
+						if (isfinite(sensor.baro_alt_meter)) {
+							baro_offset += sensor.baro_alt_meter;
+							baro_init_cnt++;
+						}
 
 					} else {
 						wait_baro = false;
@@ -418,19 +420,17 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 
 						/* transform acceleration vector from body frame to NED frame */
 						for (int i = 0; i < 3; i++) {
-							accel_NED[i] = 0.0f;
+							acc[i] = 0.0f;
 
 							for (int j = 0; j < 3; j++) {
-								accel_NED[i] += att.R[i][j] * sensor.accelerometer_m_s2[j];
+								acc[i] += att.R[i][j] * sensor.accelerometer_m_s2[j];
 							}
 						}
 
-						corr_acc[0] = accel_NED[0] - x_est[2];
-						corr_acc[1] = accel_NED[1] - y_est[2];
-						corr_acc[2] = accel_NED[2] + CONSTANTS_ONE_G - z_est[2];
+						acc[2] += CONSTANTS_ONE_G;
 
 					} else {
-						memset(corr_acc, 0, sizeof(corr_acc));
+						memset(acc, 0, sizeof(acc));
 					}
 
 					accel_timestamp = sensor.accelerometer_timestamp;
@@ -628,11 +628,9 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 							/* set position estimate to (0, 0, 0), use GPS velocity for XY */
 							x_est[0] = 0.0f;
 							x_est[1] = gps.vel_n_m_s;
-							x_est[2] = accel_NED[0];
 							y_est[0] = 0.0f;
 							y_est[1] = gps.vel_e_m_s;
 							z_est[0] = 0.0f;
-							y_est[2] = accel_NED[1];
 
 							local_pos.ref_lat = lat;
 							local_pos.ref_lon = lon;
@@ -655,10 +653,8 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 						if (reset_est) {
 							x_est[0] = gps_proj[0];
 							x_est[1] = gps.vel_n_m_s;
-							x_est[2] = accel_NED[0];
 							y_est[0] = gps_proj[1];
 							y_est[1] = gps.vel_e_m_s;
-							y_est[2] = accel_NED[1];
 						}
 
 						/* calculate correction for position */
@@ -796,26 +792,26 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 				c += att.R[j][i] * accel_bias_corr[j];
 			}
 
-			acc_bias[i] += c * params.w_acc_bias * dt;
+			if (isfinite(c)) {
+				acc_bias[i] += c * params.w_acc_bias * dt;
+			}
 		}
 
 		/* inertial filter prediction for altitude */
-		inertial_filter_predict(dt, z_est);
+		inertial_filter_predict(dt, z_est, acc[2]);
 
-		if (!(isfinite(z_est[0]) && isfinite(z_est[1]) && isfinite(z_est[2]))) {
-			write_debug_log("BAD ESTIMATE AFTER Z PREDICTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, corr_acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
+		if (!(isfinite(z_est[0]) && isfinite(z_est[1]))) {
+			write_debug_log("BAD ESTIMATE AFTER Z PREDICTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
 			memcpy(z_est, z_est_prev, sizeof(z_est));
 		}
 
 		/* inertial filter correction for altitude */
 		inertial_filter_correct(corr_baro, dt, z_est, 0, params.w_z_baro);
 		inertial_filter_correct(corr_gps[2][0], dt, z_est, 0, w_z_gps_p);
-		inertial_filter_correct(corr_acc[2], dt, z_est, 2, params.w_z_acc);
 
-		if (!(isfinite(z_est[0]) && isfinite(z_est[1]) && isfinite(z_est[2]))) {
-			write_debug_log("BAD ESTIMATE AFTER Z CORRECTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, corr_acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
+		if (!(isfinite(z_est[0]) && isfinite(z_est[1]))) {
+			write_debug_log("BAD ESTIMATE AFTER Z CORRECTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
 			memcpy(z_est, z_est_prev, sizeof(z_est));
-			memset(corr_acc, 0, sizeof(corr_acc));
 			memset(corr_gps, 0, sizeof(corr_gps));
 			corr_baro = 0;
 
@@ -825,19 +821,16 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 
 		if (can_estimate_xy) {
 			/* inertial filter prediction for position */
-			inertial_filter_predict(dt, x_est);
-			inertial_filter_predict(dt, y_est);
+			inertial_filter_predict(dt, x_est, acc[0]);
+			inertial_filter_predict(dt, y_est, acc[1]);
 
-			if (!(isfinite(x_est[0]) && isfinite(x_est[1]) && isfinite(x_est[2]) && isfinite(y_est[0]) && isfinite(y_est[1]) && isfinite(y_est[2]))) {
-				write_debug_log("BAD ESTIMATE AFTER PREDICTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, corr_acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
+			if (!(isfinite(x_est[0]) && isfinite(x_est[1]) && isfinite(y_est[0]) && isfinite(y_est[1]))) {
+				write_debug_log("BAD ESTIMATE AFTER PREDICTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
 				memcpy(x_est, x_est_prev, sizeof(x_est));
 				memcpy(y_est, y_est_prev, sizeof(y_est));
 			}
 
 			/* inertial filter correction for position */
-			inertial_filter_correct(corr_acc[0], dt, x_est, 2, params.w_xy_acc);
-			inertial_filter_correct(corr_acc[1], dt, y_est, 2, params.w_xy_acc);
-
 			if (use_flow) {
 				inertial_filter_correct(corr_flow[0], dt, x_est, 1, params.w_xy_flow * w_flow);
 				inertial_filter_correct(corr_flow[1], dt, y_est, 1, params.w_xy_flow * w_flow);
@@ -853,11 +846,10 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 				}
 			}
 
-			if (!(isfinite(x_est[0]) && isfinite(x_est[1]) && isfinite(x_est[2]) && isfinite(y_est[0]) && isfinite(y_est[1]) && isfinite(y_est[2]))) {
-				write_debug_log("BAD ESTIMATE AFTER CORRECTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, corr_acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
+			if (!(isfinite(x_est[0]) && isfinite(x_est[1]) && isfinite(y_est[0]) && isfinite(y_est[1]))) {
+				write_debug_log("BAD ESTIMATE AFTER CORRECTION", dt, x_est, y_est, z_est, x_est_prev, y_est_prev, z_est_prev, acc, corr_gps, w_xy_gps_p, w_xy_gps_v);
 				memcpy(x_est, x_est_prev, sizeof(x_est));
 				memcpy(y_est, y_est_prev, sizeof(y_est));
-				memset(corr_acc, 0, sizeof(corr_acc));
 				memset(corr_gps, 0, sizeof(corr_gps));
 				memset(corr_flow, 0, sizeof(corr_flow));
 
diff --git a/src/modules/position_estimator_inav/position_estimator_inav_params.c b/src/modules/position_estimator_inav/position_estimator_inav_params.c
index 2e4f26661..8aa08b6f2 100644
--- a/src/modules/position_estimator_inav/position_estimator_inav_params.c
+++ b/src/modules/position_estimator_inav/position_estimator_inav_params.c
@@ -42,11 +42,9 @@
 
 PARAM_DEFINE_FLOAT(INAV_W_Z_BARO, 0.5f);
 PARAM_DEFINE_FLOAT(INAV_W_Z_GPS_P, 0.005f);
-PARAM_DEFINE_FLOAT(INAV_W_Z_ACC, 20.0f);
 PARAM_DEFINE_FLOAT(INAV_W_Z_SONAR, 3.0f);
 PARAM_DEFINE_FLOAT(INAV_W_XY_GPS_P, 1.0f);
 PARAM_DEFINE_FLOAT(INAV_W_XY_GPS_V, 2.0f);
-PARAM_DEFINE_FLOAT(INAV_W_XY_ACC, 20.0f);
 PARAM_DEFINE_FLOAT(INAV_W_XY_FLOW, 5.0f);
 PARAM_DEFINE_FLOAT(INAV_W_GPS_FLOW, 0.1f);
 PARAM_DEFINE_FLOAT(INAV_W_ACC_BIAS, 0.05f);
@@ -62,11 +60,9 @@ int parameters_init(struct position_estimator_inav_param_handles *h)
 {
 	h->w_z_baro = param_find("INAV_W_Z_BARO");
 	h->w_z_gps_p = param_find("INAV_W_Z_GPS_P");
-	h->w_z_acc = param_find("INAV_W_Z_ACC");
 	h->w_z_sonar = param_find("INAV_W_Z_SONAR");
 	h->w_xy_gps_p = param_find("INAV_W_XY_GPS_P");
 	h->w_xy_gps_v = param_find("INAV_W_XY_GPS_V");
-	h->w_xy_acc = param_find("INAV_W_XY_ACC");
 	h->w_xy_flow = param_find("INAV_W_XY_FLOW");
 	h->w_gps_flow = param_find("INAV_W_GPS_FLOW");
 	h->w_acc_bias = param_find("INAV_W_ACC_BIAS");
@@ -85,11 +81,9 @@ int parameters_update(const struct position_estimator_inav_param_handles *h, str
 {
 	param_get(h->w_z_baro, &(p->w_z_baro));
 	param_get(h->w_z_gps_p, &(p->w_z_gps_p));
-	param_get(h->w_z_acc, &(p->w_z_acc));
 	param_get(h->w_z_sonar, &(p->w_z_sonar));
 	param_get(h->w_xy_gps_p, &(p->w_xy_gps_p));
 	param_get(h->w_xy_gps_v, &(p->w_xy_gps_v));
-	param_get(h->w_xy_acc, &(p->w_xy_acc));
 	param_get(h->w_xy_flow, &(p->w_xy_flow));
 	param_get(h->w_gps_flow, &(p->w_gps_flow));
 	param_get(h->w_acc_bias, &(p->w_acc_bias));
diff --git a/src/modules/position_estimator_inav/position_estimator_inav_params.h b/src/modules/position_estimator_inav/position_estimator_inav_params.h
index e2be079d3..08ec996a1 100644
--- a/src/modules/position_estimator_inav/position_estimator_inav_params.h
+++ b/src/modules/position_estimator_inav/position_estimator_inav_params.h
@@ -43,11 +43,9 @@
 struct position_estimator_inav_params {
 	float w_z_baro;
 	float w_z_gps_p;
-	float w_z_acc;
 	float w_z_sonar;
 	float w_xy_gps_p;
 	float w_xy_gps_v;
-	float w_xy_acc;
 	float w_xy_flow;
 	float w_gps_flow;
 	float w_acc_bias;
@@ -63,11 +61,9 @@ struct position_estimator_inav_params {
 struct position_estimator_inav_param_handles {
 	param_t w_z_baro;
 	param_t w_z_gps_p;
-	param_t w_z_acc;
 	param_t w_z_sonar;
 	param_t w_xy_gps_p;
 	param_t w_xy_gps_v;
-	param_t w_xy_acc;
 	param_t w_xy_flow;
 	param_t w_gps_flow;
 	param_t w_acc_bias;
diff --git a/src/modules/uORB/topics/actuator_armed.h b/src/modules/uORB/topics/actuator_armed.h
index 6e944ffee..a98d3fc3a 100644
--- a/src/modules/uORB/topics/actuator_armed.h
+++ b/src/modules/uORB/topics/actuator_armed.h
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2013 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 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
@@ -44,15 +44,25 @@
 #include <stdint.h>
 #include "../uORB.h"
 
+/**
+ * @addtogroup topics
+ * @{
+ */
+
 /** global 'actuator output is live' control. */
 struct actuator_armed_s {
 
-	uint64_t	timestamp;
-	bool	armed;		/**< Set to true if system is armed */
-	bool	ready_to_arm;	/**< Set to true if system is ready to be armed */
-	bool	lockdown;	/**< Set to true if actuators are forced to being disabled (due to emergency or HIL) */
+	uint64_t	timestamp;	/**< Microseconds since system boot */
+	bool		armed;		/**< Set to true if system is armed */
+	bool		ready_to_arm;	/**< Set to true if system is ready to be armed */
+	bool		lockdown;	/**< Set to true if actuators are forced to being disabled (due to emergency or HIL) */
 };
 
+/**
+ * @}
+ */
+
+/* register this as object request broker structure */
 ORB_DECLARE(actuator_armed);
 
 #endif
\ No newline at end of file