Merge remote-tracking branch 'upstream/master' into dev_ros

Conflicts:
	.gitmodules

82 files changed, 649 insertions, 86 deletions

diff --git a/.gitmodules b/.gitmodules
index d0039b38d..c869803b7 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -13,3 +13,6 @@
 [submodule "Tools/gencpp"]
 	path = Tools/gencpp
 	url = https://github.com/ros/gencpp.git
+[submodule "unittests/gtest"]
+	path = unittests/gtest
+	url = https://github.com/sjwilks/gtest.git
diff --git a/Makefile b/Makefile
index 04737c3b3..b800459cb 100644
--- a/Makefile
+++ b/Makefile
@@ -261,14 +261,16 @@ tests:
 #
 .PHONY:	clean
 clean:
-	$(Q) $(RMDIR) $(BUILD_DIR)*.build > /dev/null
-	$(Q) $(REMOVE) $(IMAGE_DIR)*.px4 > /dev/null
+	@echo > /dev/null
+	$(Q) $(RMDIR) $(BUILD_DIR)*.build
+	$(Q) $(REMOVE) $(IMAGE_DIR)*.px4
 
 .PHONY:	distclean
 distclean: clean
-	$(Q) $(REMOVE) $(ARCHIVE_DIR)*.export > /dev/null
-	$(Q) $(MAKE) -C $(NUTTX_SRC) -r $(MQUIET) distclean > /dev/null
-	$(Q) (cd $(NUTTX_SRC)/configs && $(FIND) . -maxdepth 1 -type l -delete) > /dev/null
+	@echo > /dev/null
+	$(Q) $(REMOVE) $(ARCHIVE_DIR)*.export
+	$(Q) $(MAKE) -C $(NUTTX_SRC) -r $(MQUIET) distclean
+	$(Q) (cd $(NUTTX_SRC)/configs && $(FIND) . -maxdepth 1 -type l -delete)
 
 #
 # Print some help text
diff --git a/NuttX b/NuttX
-Subproject b66de6506941dc7628efcf65e5543c0e3cb05a8
+Subproject 3c36467c0d5572431a09ae50013328a4693ee07
diff --git a/ROMFS/px4fmu_common/init.d/rc.sensors b/ROMFS/px4fmu_common/init.d/rc.sensors
index e6fc535a6..973db9017 100644
--- a/ROMFS/px4fmu_common/init.d/rc.sensors
+++ b/ROMFS/px4fmu_common/init.d/rc.sensors
@@ -56,7 +56,6 @@ fi
 
 if meas_airspeed start
 then
-	echo "[i] Using MEAS airspeed sensor"
 else
 	if ets_airspeed start
 	then
@@ -67,6 +66,7 @@ else
 	fi
 fi
 
+# Check for flow sensor
 if px4flow start
 then
 fi
diff --git a/ROMFS/px4fmu_common/init.d/rc.usb b/ROMFS/px4fmu_common/init.d/rc.usb
index ee040a706..b3de8e590 100644
--- a/ROMFS/px4fmu_common/init.d/rc.usb
+++ b/ROMFS/px4fmu_common/init.d/rc.usb
@@ -25,6 +25,7 @@ mavlink stream -d /dev/ttyACM0 -s SERVO_OUTPUT_RAW_0 -r 20
 usleep 100000
 mavlink stream -d /dev/ttyACM0 -s POSITION_TARGET_GLOBAL_INT -r 10
 usleep 100000
+mavlink stream -d /dev/ttyACM0 -s LOCAL_POSITION_NED -r 30
 
 # Exit shell to make it available to MAVLink
 exit
diff --git a/ROMFS/px4fmu_common/init.d/rcS b/ROMFS/px4fmu_common/init.d/rcS
index 14fc8d2b4..26b729aad 100644
--- a/ROMFS/px4fmu_common/init.d/rcS
+++ b/ROMFS/px4fmu_common/init.d/rcS
@@ -430,6 +430,16 @@ then
 	unset MAVLINK_F
 
 	#
+	# MAVLink onboard / TELEM2
+	#
+	if ver hwcmp PX4FMU_V2
+	then
+		if param compare SYS_COMPANION 921600
+		then
+			mavlink start -d /dev/ttyS2 -b 921600 -m onboard
+		fi
+	fi
+
 	# UAVCAN
 	#
 	sh /etc/init.d/rc.uavcan
diff --git a/makefiles/config_px4fmu-v2_default.mk b/makefiles/config_px4fmu-v2_default.mk
index ce12a2157..86b2f7cf2 100644
--- a/makefiles/config_px4fmu-v2_default.mk
+++ b/makefiles/config_px4fmu-v2_default.mk
@@ -32,6 +32,7 @@ MODULES		+= drivers/ll40ls
 # MODULES		+= drivers/trone
 MODULES		+= drivers/gps
 MODULES		+= drivers/hil
+MODULES		+= drivers/hott
 MODULES		+= drivers/hott/hott_telemetry
 MODULES		+= drivers/hott/hott_sensors
 # MODULES		+= drivers/blinkm
diff --git a/makefiles/toolchain_gnu-arm-eabi.mk b/makefiles/toolchain_gnu-arm-eabi.mk
index b98b1a0af..8367cf056 100644
--- a/makefiles/toolchain_gnu-arm-eabi.mk
+++ b/makefiles/toolchain_gnu-arm-eabi.mk
@@ -127,6 +127,7 @@ ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=gnu++0x -fno-threadsafe-statics
 #
 ARCHWARNINGS		 = -Wall \
 			   -Wextra \
+			   -Werror \
 			   -Wdouble-promotion \
 			   -Wshadow \
 			   -Wfloat-equal \
diff --git a/nuttx-configs/aerocore/nsh/Make.defs b/nuttx-configs/aerocore/nsh/Make.defs
index c7a1b71bb..c1f5a8ac4 100644
--- a/nuttx-configs/aerocore/nsh/Make.defs
+++ b/nuttx-configs/aerocore/nsh/Make.defs
@@ -119,6 +119,7 @@ endif
 ARCHCFLAGS		 = -std=gnu99
 ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=gnu++0x
 ARCHWARNINGS		 = -Wall \
+			   -Wno-sign-compare \
 			   -Wextra \
 			   -Wdouble-promotion \
 			   -Wshadow \
diff --git a/nuttx-configs/px4fmu-v1/nsh/Make.defs b/nuttx-configs/px4fmu-v1/nsh/Make.defs
index f055cfddf..5e28f2473 100644
--- a/nuttx-configs/px4fmu-v1/nsh/Make.defs
+++ b/nuttx-configs/px4fmu-v1/nsh/Make.defs
@@ -119,6 +119,7 @@ endif
 ARCHCFLAGS		 = -std=gnu99
 ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=gnu++0x
 ARCHWARNINGS		 = -Wall \
+			   -Wno-sign-compare \
 			   -Wextra \
 			   -Wdouble-promotion \
 			   -Wshadow \
diff --git a/nuttx-configs/px4fmu-v1/nsh/defconfig b/nuttx-configs/px4fmu-v1/nsh/defconfig
index edf49b26e..fade1f0c6 100644
--- a/nuttx-configs/px4fmu-v1/nsh/defconfig
+++ b/nuttx-configs/px4fmu-v1/nsh/defconfig
@@ -404,7 +404,7 @@ CONFIG_SIG_SIGWORK=4
 CONFIG_MAX_TASKS=32
 CONFIG_MAX_TASK_ARGS=10
 CONFIG_NPTHREAD_KEYS=4
-CONFIG_NFILE_DESCRIPTORS=38
+CONFIG_NFILE_DESCRIPTORS=42
 CONFIG_NFILE_STREAMS=8
 CONFIG_NAME_MAX=32
 CONFIG_PREALLOC_MQ_MSGS=4
diff --git a/nuttx-configs/px4fmu-v2/nsh/Make.defs b/nuttx-configs/px4fmu-v2/nsh/Make.defs
index b3cf28b7a..e0e868870 100644
--- a/nuttx-configs/px4fmu-v2/nsh/Make.defs
+++ b/nuttx-configs/px4fmu-v2/nsh/Make.defs
@@ -119,6 +119,7 @@ endif
 ARCHCFLAGS		 = -std=gnu99
 ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=c++11
 ARCHWARNINGS		 = -Wall \
+			   -Wno-sign-compare \
 			   -Wextra \
 			   -Wdouble-promotion \
 			   -Wshadow \
diff --git a/nuttx-configs/px4fmu-v2/nsh/defconfig b/nuttx-configs/px4fmu-v2/nsh/defconfig
index e31f40cd2..90dde6294 100644
--- a/nuttx-configs/px4fmu-v2/nsh/defconfig
+++ b/nuttx-configs/px4fmu-v2/nsh/defconfig
@@ -438,7 +438,7 @@ CONFIG_SIG_SIGWORK=4
 CONFIG_MAX_TASKS=32
 CONFIG_MAX_TASK_ARGS=10
 CONFIG_NPTHREAD_KEYS=4
-CONFIG_NFILE_DESCRIPTORS=38
+CONFIG_NFILE_DESCRIPTORS=42
 CONFIG_NFILE_STREAMS=8
 CONFIG_NAME_MAX=32
 CONFIG_PREALLOC_MQ_MSGS=4
diff --git a/nuttx-configs/px4io-v1/nsh/Make.defs b/nuttx-configs/px4io-v1/nsh/Make.defs
index e96be6a1f..b4f5577ae 100644
--- a/nuttx-configs/px4io-v1/nsh/Make.defs
+++ b/nuttx-configs/px4io-v1/nsh/Make.defs
@@ -108,6 +108,7 @@ endif
 ARCHCFLAGS		 = -std=gnu99
 ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=gnu++0x
 ARCHWARNINGS		 = -Wall \
+         -Wno-sign-compare \
 			   -Wextra \
 			   -Wdouble-promotion \
 			   -Wshadow \
diff --git a/nuttx-configs/px4io-v2/nsh/Make.defs b/nuttx-configs/px4io-v2/nsh/Make.defs
index 4a8df2738..51420eb23 100644
--- a/nuttx-configs/px4io-v2/nsh/Make.defs
+++ b/nuttx-configs/px4io-v2/nsh/Make.defs
@@ -108,6 +108,7 @@ endif
 ARCHCFLAGS		 = -std=gnu99
 ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=gnu++0x
 ARCHWARNINGS		 = -Wall \
+         -Wno-sign-compare \
 			   -Wextra \
 			   -Wdouble-promotion \
 			   -Wshadow \
diff --git a/src/drivers/ardrone_interface/ardrone_interface.c b/src/drivers/ardrone_interface/ardrone_interface.c
index 9d2c1441d..7f1b21a95 100644
--- a/src/drivers/ardrone_interface/ardrone_interface.c
+++ b/src/drivers/ardrone_interface/ardrone_interface.c
@@ -121,7 +121,7 @@ int ardrone_interface_main(int argc, char *argv[])
 						    SCHED_PRIORITY_MAX - 15,
 						    1100,
 						    ardrone_interface_thread_main,
-						    (argv) ? (const char **)&argv[2] : (const char **)NULL);
+						    (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/drivers/boards/aerocore/aerocore_led.c b/src/drivers/boards/aerocore/aerocore_led.c
index e40d1730c..94a716029 100644
--- a/src/drivers/boards/aerocore/aerocore_led.c
+++ b/src/drivers/boards/aerocore/aerocore_led.c
@@ -45,6 +45,7 @@
 #include "board_config.h"
 
 #include <arch/board/board.h>
+#include <systemlib/err.h>
 
 /*
  * Ideally we'd be able to get these from up_internal.h,
@@ -54,7 +55,7 @@
  * CONFIG_ARCH_LEDS configuration switch.
  */
 __BEGIN_DECLS
-extern void led_init();
+extern void led_init(void);
 extern void led_on(int led);
 extern void led_off(int led);
 extern void led_toggle(int led);
diff --git a/src/drivers/boards/px4fmu-v2/board_config.h b/src/drivers/boards/px4fmu-v2/board_config.h
index ee365e47c..2fd8bc724 100644
--- a/src/drivers/boards/px4fmu-v2/board_config.h
+++ b/src/drivers/boards/px4fmu-v2/board_config.h
@@ -105,6 +105,7 @@ __BEGIN_DECLS
 #define GPIO_SPI_CS_ACCEL_MAG	(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN15)
 #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_HMC		(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN1)
 #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)
@@ -119,6 +120,7 @@ __BEGIN_DECLS
 #define PX4_SPIDEV_ACCEL_MAG	2
 #define PX4_SPIDEV_BARO		3
 #define PX4_SPIDEV_MPU		4
+#define PX4_SPIDEV_HMC		5
 
 /* External bus */
 #define PX4_SPIDEV_EXT0		1
diff --git a/src/drivers/boards/px4fmu-v2/px4fmu_spi.c b/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
index 8c37d31a7..27f193513 100644
--- a/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
+++ b/src/drivers/boards/px4fmu-v2/px4fmu_spi.c
@@ -73,6 +73,7 @@ __EXPORT void weak_function stm32_spiinitialize(void)
 	stm32_configgpio(GPIO_SPI_CS_GYRO);
 	stm32_configgpio(GPIO_SPI_CS_ACCEL_MAG);
 	stm32_configgpio(GPIO_SPI_CS_BARO);
+	stm32_configgpio(GPIO_SPI_CS_HMC);
 	stm32_configgpio(GPIO_SPI_CS_MPU);
 
 	/* De-activate all peripherals,
@@ -82,6 +83,7 @@ __EXPORT void weak_function stm32_spiinitialize(void)
 	stm32_gpiowrite(GPIO_SPI_CS_GYRO, 1);
 	stm32_gpiowrite(GPIO_SPI_CS_ACCEL_MAG, 1);
 	stm32_gpiowrite(GPIO_SPI_CS_BARO, 1);
+	stm32_gpiowrite(GPIO_SPI_CS_HMC, 1);
 	stm32_gpiowrite(GPIO_SPI_CS_MPU, 1);
 
 	stm32_configgpio(GPIO_EXTI_GYRO_DRDY);
@@ -117,6 +119,7 @@ __EXPORT void stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid,
 		stm32_gpiowrite(GPIO_SPI_CS_GYRO, !selected);
 		stm32_gpiowrite(GPIO_SPI_CS_ACCEL_MAG, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_BARO, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_HMC, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_MPU, 1);
 		break;
 
@@ -125,6 +128,7 @@ __EXPORT void stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid,
 		stm32_gpiowrite(GPIO_SPI_CS_GYRO, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_ACCEL_MAG, !selected);
 		stm32_gpiowrite(GPIO_SPI_CS_BARO, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_HMC, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_MPU, 1);
 		break;
 
@@ -133,6 +137,16 @@ __EXPORT void stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid,
 		stm32_gpiowrite(GPIO_SPI_CS_GYRO, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_ACCEL_MAG, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_BARO, !selected);
+		stm32_gpiowrite(GPIO_SPI_CS_HMC, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_MPU, 1);
+		break;
+
+	case PX4_SPIDEV_HMC:
+		/* Making sure the other peripherals are not selected */
+		stm32_gpiowrite(GPIO_SPI_CS_GYRO, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_ACCEL_MAG, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_BARO, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_HMC, !selected);
 		stm32_gpiowrite(GPIO_SPI_CS_MPU, 1);
 		break;
 
@@ -141,6 +155,7 @@ __EXPORT void stm32_spi1select(FAR struct spi_dev_s *dev, enum spi_dev_e devid,
 		stm32_gpiowrite(GPIO_SPI_CS_GYRO, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_ACCEL_MAG, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_BARO, 1);
+		stm32_gpiowrite(GPIO_SPI_CS_HMC, 1);
 		stm32_gpiowrite(GPIO_SPI_CS_MPU, !selected);
 		break;
 
diff --git a/src/drivers/frsky_telemetry/frsky_telemetry.c b/src/drivers/frsky_telemetry/frsky_telemetry.c
index bccdf1190..5035600ef 100644
--- a/src/drivers/frsky_telemetry/frsky_telemetry.c
+++ b/src/drivers/frsky_telemetry/frsky_telemetry.c
@@ -221,7 +221,7 @@ int frsky_telemetry_main(int argc, char *argv[])
 					  SCHED_PRIORITY_DEFAULT,
 					  2000,
 					  frsky_telemetry_thread_main,
-					  (const char **)argv);
+					  (char * const *)argv);
 
 		while (!thread_running) {
 			usleep(200);
diff --git a/src/drivers/hott/comms.h b/src/drivers/hott/comms.h
index f5608122f..0a586a8fd 100644
--- a/src/drivers/hott/comms.h
+++ b/src/drivers/hott/comms.h
@@ -41,6 +41,6 @@
 #ifndef COMMS_H_
 #define COMMS_H
 
-int open_uart(const char *device);
+__EXPORT int open_uart(const char *device);
 
 #endif /* COMMS_H_ */
diff --git a/src/drivers/hott/hott_sensors/hott_sensors.cpp b/src/drivers/hott/hott_sensors/hott_sensors.cpp
index 8ab9d8d55..4b8e0c0b0 100644
--- a/src/drivers/hott/hott_sensors/hott_sensors.cpp
+++ b/src/drivers/hott/hott_sensors/hott_sensors.cpp
@@ -214,7 +214,7 @@ hott_sensors_main(int argc, char *argv[])
 					     SCHED_PRIORITY_DEFAULT,
 					     1024,
 					     hott_sensors_thread_main,
-					     (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					     (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/drivers/hott/hott_sensors/module.mk b/src/drivers/hott/hott_sensors/module.mk
index 47aea6caf..25a6f0ac0 100644
--- a/src/drivers/hott/hott_sensors/module.mk
+++ b/src/drivers/hott/hott_sensors/module.mk
@@ -37,8 +37,6 @@
 
 MODULE_COMMAND	= hott_sensors
 
-SRCS		= hott_sensors.cpp \
-		  ../messages.cpp \
-		  ../comms.cpp
+SRCS		= hott_sensors.cpp
 
 MAXOPTIMIZATION	 = -Os
diff --git a/src/drivers/hott/hott_telemetry/hott_telemetry.cpp b/src/drivers/hott/hott_telemetry/hott_telemetry.cpp
index edbb14172..17a24d104 100644
--- a/src/drivers/hott/hott_telemetry/hott_telemetry.cpp
+++ b/src/drivers/hott/hott_telemetry/hott_telemetry.cpp
@@ -240,7 +240,7 @@ hott_telemetry_main(int argc, char *argv[])
 					 SCHED_PRIORITY_DEFAULT,
 					 2048,
 					 hott_telemetry_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/drivers/hott/hott_telemetry/module.mk b/src/drivers/hott/hott_telemetry/module.mk
index cd7bdbc85..9de47b356 100644
--- a/src/drivers/hott/hott_telemetry/module.mk
+++ b/src/drivers/hott/hott_telemetry/module.mk
@@ -37,8 +37,6 @@
 
 MODULE_COMMAND	= hott_telemetry
 
-SRCS		= hott_telemetry.cpp \
-		  ../messages.cpp \
-		  ../comms.cpp
+SRCS		= hott_telemetry.cpp
 
 MAXOPTIMIZATION	 = -Os
diff --git a/src/drivers/hott/messages.h b/src/drivers/hott/messages.h
index 224f8fc56..a116a50dd 100644
--- a/src/drivers/hott/messages.h
+++ b/src/drivers/hott/messages.h
@@ -235,15 +235,15 @@ struct gps_module_msg {
 // The maximum size of a message.
 #define MAX_MESSAGE_BUFFER_SIZE 45
 
-void init_sub_messages(void);
-void init_pub_messages(void);
-void build_gam_request(uint8_t *buffer, size_t *size);
-void publish_gam_message(const uint8_t *buffer);
-void build_eam_response(uint8_t *buffer, size_t *size);
-void build_gam_response(uint8_t *buffer, size_t *size);
-void build_gps_response(uint8_t *buffer, size_t *size);
-float _get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);
-void convert_to_degrees_minutes_seconds(double lat, int *deg, int *min, int *sec);
+__EXPORT void init_sub_messages(void);
+__EXPORT void init_pub_messages(void);
+__EXPORT void build_gam_request(uint8_t *buffer, size_t *size);
+__EXPORT void publish_gam_message(const uint8_t *buffer);
+__EXPORT void build_eam_response(uint8_t *buffer, size_t *size);
+__EXPORT void build_gam_response(uint8_t *buffer, size_t *size);
+__EXPORT void build_gps_response(uint8_t *buffer, size_t *size);
+__EXPORT float _get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);
+__EXPORT void convert_to_degrees_minutes_seconds(double lat, int *deg, int *min, int *sec);
 
 
 #endif /* MESSAGES_H_ */
diff --git a/src/drivers/hott/module.mk b/src/drivers/hott/module.mk
new file mode 100644
index 000000000..31a66d491
--- /dev/null
+++ b/src/drivers/hott/module.mk
@@ -0,0 +1,41 @@
+############################################################################
+#
+#   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.
+#
+############################################################################
+
+#
+# Graupner HoTT Sensors messages.
+#
+
+SRCS		= messages.cpp \
+			  comms.cpp
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/drivers/px4flow/module.mk b/src/drivers/px4flow/module.mk
index 460bec7b9..ecd3e804a 100644
--- a/src/drivers/px4flow/module.mk
+++ b/src/drivers/px4flow/module.mk
@@ -40,3 +40,5 @@ MODULE_COMMAND	= px4flow
 SRCS		= px4flow.cpp
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACXXFLAGS = -Wno-attributes
diff --git a/src/drivers/px4flow/px4flow.cpp b/src/drivers/px4flow/px4flow.cpp
index 09ec4bf96..62308fc65 100644
--- a/src/drivers/px4flow/px4flow.cpp
+++ b/src/drivers/px4flow/px4flow.cpp
@@ -106,7 +106,7 @@ struct i2c_frame {
 };
 struct i2c_frame f;
 
-typedef struct i2c_integral_frame {
+struct i2c_integral_frame {
 	uint16_t frame_count_since_last_readout;
 	int16_t pixel_flow_x_integral;
 	int16_t pixel_flow_y_integral;
diff --git a/src/drivers/roboclaw/roboclaw_main.cpp b/src/drivers/roboclaw/roboclaw_main.cpp
index 44ed03254..83086fd7c 100644
--- a/src/drivers/roboclaw/roboclaw_main.cpp
+++ b/src/drivers/roboclaw/roboclaw_main.cpp
@@ -109,7 +109,7 @@ int roboclaw_main(int argc, char *argv[])
 					 SCHED_PRIORITY_MAX - 10,
 					 2048,
 					 roboclaw_thread_main,
-					 (const char **)argv);
+					 (char * const *)argv);
 		exit(0);
 
 	} else if (!strcmp(argv[1], "test")) {
diff --git a/src/drivers/sf0x/sf0x.cpp b/src/drivers/sf0x/sf0x.cpp
index 4301750f0..8e62e0d4b 100644
--- a/src/drivers/sf0x/sf0x.cpp
+++ b/src/drivers/sf0x/sf0x.cpp
@@ -90,7 +90,9 @@ static const int ERROR = -1;
 #define SF0X_TAKE_RANGE_REG		'd'
 #define SF02F_MIN_DISTANCE		0.0f
 #define SF02F_MAX_DISTANCE		40.0f
-#define SF0X_DEFAULT_PORT		"/dev/ttyS2"
+
+// designated SERIAL4/5 on Pixhawk
+#define SF0X_DEFAULT_PORT		"/dev/ttyS6"
 
 class SF0X : public device::CDev
 {
diff --git a/src/drivers/trone/trone.cpp b/src/drivers/trone/trone.cpp
index 83b5c987e..cf3546669 100644
--- a/src/drivers/trone/trone.cpp
+++ b/src/drivers/trone/trone.cpp
@@ -206,7 +206,7 @@ static const uint8_t crc_table[] = {
     0xfa, 0xfd, 0xf4, 0xf3
 };
 
-uint8_t crc8(uint8_t *p, uint8_t len){
+static uint8_t crc8(uint8_t *p, uint8_t len) {
         uint16_t i;
         uint16_t crc = 0x0;
 
diff --git a/src/examples/fixedwing_control/main.c b/src/examples/fixedwing_control/main.c
index 6a5cbcd30..fcbb54c8e 100644
--- a/src/examples/fixedwing_control/main.c
+++ b/src/examples/fixedwing_control/main.c
@@ -423,7 +423,7 @@ int ex_fixedwing_control_main(int argc, char *argv[])
 					 SCHED_PRIORITY_MAX - 20,
 					 2048,
 					 fixedwing_control_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		thread_running = true;
 		exit(0);
 	}
diff --git a/src/examples/fixedwing_control/module.mk b/src/examples/fixedwing_control/module.mk
index a2a9eb113..f6c882ead 100644
--- a/src/examples/fixedwing_control/module.mk
+++ b/src/examples/fixedwing_control/module.mk
@@ -41,3 +41,5 @@ SRCS		= main.c \
 		  params.c
 
 MODULE_STACKSIZE = 1200
+
+EXTRACFLAGS = -Wframe-larger-than=1200
diff --git a/src/examples/flow_position_estimator/flow_position_estimator_main.c b/src/examples/flow_position_estimator/flow_position_estimator_main.c
index 5a23932d3..1ac0c2d04 100644
--- a/src/examples/flow_position_estimator/flow_position_estimator_main.c
+++ b/src/examples/flow_position_estimator/flow_position_estimator_main.c
@@ -115,7 +115,7 @@ int flow_position_estimator_main(int argc, char *argv[])
 					 SCHED_PRIORITY_MAX - 5,
 					 4000,
 					 flow_position_estimator_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/examples/flow_position_estimator/module.mk b/src/examples/flow_position_estimator/module.mk
index 88c9ceb93..5c6e29f8f 100644
--- a/src/examples/flow_position_estimator/module.mk
+++ b/src/examples/flow_position_estimator/module.mk
@@ -39,3 +39,5 @@ MODULE_COMMAND		= flow_position_estimator
 
 SRCS		= flow_position_estimator_main.c \
 		  flow_position_estimator_params.c
+		  
+EXTRACFLAGS = -Wno-float-equal
diff --git a/src/examples/hwtest/hwtest.c b/src/examples/hwtest/hwtest.c
index d3b10f46e..95ff346bb 100644
--- a/src/examples/hwtest/hwtest.c
+++ b/src/examples/hwtest/hwtest.c
@@ -39,13 +39,15 @@
  * @author Lorenz Meier <lm@inf.ethz.ch>
  */
 
-#include <nuttx/config.h>
 #include <stdio.h>
-#include <systemlib/err.h>
+#include <string.h>
+
 #include <drivers/drv_hrt.h>
-#include <uORB/uORB.h>
-#include <uORB/topics/actuator_controls.h>
+#include <nuttx/config.h>
+#include <systemlib/err.h>
 #include <uORB/topics/actuator_armed.h>
+#include <uORB/topics/actuator_controls.h>
+#include <uORB/uORB.h>
 
 __EXPORT int ex_hwtest_main(int argc, char *argv[]);
 
@@ -53,7 +55,7 @@ int ex_hwtest_main(int argc, char *argv[])
 {
 	warnx("DO NOT FORGET TO STOP THE COMMANDER APP!");
 	warnx("(run <commander stop> to do so)");
-    warnx("usage: http://px4.io/dev/examples/write_output");
+	warnx("usage: http://px4.io/dev/examples/write_output");
 
 	struct actuator_controls_s actuators;
 	memset(&actuators, 0, sizeof(actuators));
diff --git a/src/examples/matlab_csv_serial/matlab_csv_serial.c b/src/examples/matlab_csv_serial/matlab_csv_serial.c
index c66bebeec..a95f45d1a 100644
--- a/src/examples/matlab_csv_serial/matlab_csv_serial.c
+++ b/src/examples/matlab_csv_serial/matlab_csv_serial.c
@@ -107,7 +107,7 @@ int matlab_csv_serial_main(int argc, char *argv[])
 					 SCHED_PRIORITY_MAX - 5,
 					 2000,
 					 matlab_csv_serial_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/examples/px4_daemon_app/px4_daemon_app.c b/src/examples/px4_daemon_app/px4_daemon_app.c
index 3eaf14148..45d541137 100644
--- a/src/examples/px4_daemon_app/px4_daemon_app.c
+++ b/src/examples/px4_daemon_app/px4_daemon_app.c
@@ -38,10 +38,13 @@
  * @author Example User <mail@example.com>
  */
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
 #include <nuttx/config.h>
 #include <nuttx/sched.h>
-#include <unistd.h>
-#include <stdio.h>
 
 #include <systemlib/systemlib.h>
 #include <systemlib/err.h>
@@ -100,7 +103,7 @@ int px4_daemon_app_main(int argc, char *argv[])
 					 SCHED_PRIORITY_DEFAULT,
 					 2000,
 					 px4_daemon_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/lib/conversion/rotation.cpp b/src/lib/conversion/rotation.cpp
index e17715733..1fe36d395 100644
--- a/src/lib/conversion/rotation.cpp
+++ b/src/lib/conversion/rotation.cpp
@@ -181,6 +181,11 @@ rotate_3f(enum Rotation rot, float &x, float &y, float &z)
         x = tmp;
         return;
     }
+    case ROTATION_ROLL_270_YAW_270: {
+        tmp = z; z = -y; y = tmp;
+        tmp = x; x = y; y = -tmp;
+        return;
+    }
     case ROTATION_PITCH_90: {
         tmp = z; z = -x; x = tmp;
         return;
diff --git a/src/lib/rc/st24.c b/src/lib/rc/st24.c
index e8a791b8f..5c53a1602 100644
--- a/src/lib/rc/st24.c
+++ b/src/lib/rc/st24.c
@@ -72,7 +72,7 @@ const char *decode_states[] = {"UNSYNCED",
 #define ST24_SCALE_OFFSET (int)(ST24_TARGET_MIN - (ST24_SCALE_FACTOR * ST24_RANGE_MIN + 0.5f))
 
 static enum ST24_DECODE_STATE _decode_state = ST24_DECODE_STATE_UNSYNCED;
-static unsigned _rxlen;
+static uint8_t _rxlen;
 
 static ReceiverFcPacket _rxpacket;
 
diff --git a/src/modules/attitude_estimator_ekf/attitude_estimator_ekf_main.cpp b/src/modules/attitude_estimator_ekf/attitude_estimator_ekf_main.cpp
index 4c64c88ae..d68f12c8e 100755
--- a/src/modules/attitude_estimator_ekf/attitude_estimator_ekf_main.cpp
+++ b/src/modules/attitude_estimator_ekf/attitude_estimator_ekf_main.cpp
@@ -63,6 +63,7 @@
 #include <uORB/topics/vehicle_gps_position.h>
 #include <uORB/topics/vehicle_global_position.h>
 #include <uORB/topics/parameter_update.h>
+#include <uORB/topics/vision_position_estimate.h>
 #include <drivers/drv_hrt.h>
 
 #include <lib/mathlib/mathlib.h>
@@ -134,7 +135,7 @@ int attitude_estimator_ekf_main(int argc, char *argv[])
 					      SCHED_PRIORITY_MAX - 5,
 					      7200,
 					      attitude_estimator_ekf_thread_main,
-					      (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					      (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
@@ -207,7 +208,6 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 			     };		/**< init: identity matrix */
 
 	float debugOutput[4] = { 0.0f };
-
 	int overloadcounter = 19;
 
 	/* Initialize filter */
@@ -220,6 +220,8 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 	memset(&raw, 0, sizeof(raw));
 	struct vehicle_gps_position_s gps;
 	memset(&gps, 0, sizeof(gps));
+	gps.eph = 100000;
+	gps.epv = 100000;
 	struct vehicle_global_position_s global_pos;
 	memset(&global_pos, 0, sizeof(global_pos));
 	struct vehicle_attitude_s att;
@@ -258,9 +260,12 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 	/* subscribe to param changes */
 	int sub_params = orb_subscribe(ORB_ID(parameter_update));
 
-	/* subscribe to control mode*/
+	/* subscribe to control mode */
 	int sub_control_mode = orb_subscribe(ORB_ID(vehicle_control_mode));
 
+	/* subscribe to vision estimate */
+	int vision_sub = orb_subscribe(ORB_ID(vision_position_estimate));
+
 	/* advertise attitude */
 	orb_advert_t pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
 
@@ -268,14 +273,11 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 
 	thread_running = true;
 
-	/* advertise debug value */
-	// struct debug_key_value_s dbg = { .key = "", .value = 0.0f };
-	// orb_advert_t pub_dbg = -1;
-
 	/* keep track of sensor updates */
 	uint64_t sensor_last_timestamp[3] = {0, 0, 0};
 
-	struct attitude_estimator_ekf_params ekf_params = { 0 };
+	struct attitude_estimator_ekf_params ekf_params;
+	memset(&ekf_params, 0, sizeof(ekf_params));
 
 	struct attitude_estimator_ekf_param_handles ekf_param_handles = { 0 };
 
@@ -293,6 +295,8 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 	math::Matrix<3, 3> R_decl;
 	R_decl.identity();
 
+	struct vision_position_estimate vision {};
+
 	/* register the perf counter */
 	perf_counter_t ekf_loop_perf = perf_alloc(PC_ELAPSED, "attitude_estimator_ekf");
 
@@ -313,8 +317,7 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 			orb_copy(ORB_ID(vehicle_control_mode), sub_control_mode, &control_mode);
 
 			if (!control_mode.flag_system_hil_enabled) {
-				fprintf(stderr,
-					"[att ekf] WARNING: Not getting sensors - sensor app running?\n");
+				warnx("WARNING: Not getting sensors - sensor app running?");
 			}
 
 		} else {
@@ -449,9 +452,30 @@ const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
 						sensor_last_timestamp[2] = raw.magnetometer_timestamp;
 					}
 
-					z_k[6] = raw.magnetometer_ga[0];
-					z_k[7] = raw.magnetometer_ga[1];
-					z_k[8] = raw.magnetometer_ga[2];
+					bool vision_updated = false;
+					orb_check(vision_sub, &vision_updated);
+
+					if (vision_updated) {
+						orb_copy(ORB_ID(vision_position_estimate), vision_sub, &vision);
+					}
+
+					if (vision.timestamp_boot > 0 && (hrt_elapsed_time(&vision.timestamp_boot) < 500000)) {
+
+						math::Quaternion q(vision.q);
+						math::Matrix<3, 3> Rvis = q.to_dcm();
+
+						math::Vector<3> v(1.0f, 0.0f, 0.4f);
+
+						math::Vector<3> vn = Rvis * v;
+
+						z_k[6] = vn(0);
+						z_k[7] = vn(1);
+						z_k[8] = vn(2);
+					} else {
+						z_k[6] = raw.magnetometer_ga[0];
+						z_k[7] = raw.magnetometer_ga[1];
+						z_k[8] = raw.magnetometer_ga[2];
+					}
 
 					uint64_t now = hrt_absolute_time();
 					unsigned int time_elapsed = now - last_run;
diff --git a/src/modules/attitude_estimator_ekf/module.mk b/src/modules/attitude_estimator_ekf/module.mk
index 749b0a91c..1158536e1 100644
--- a/src/modules/attitude_estimator_ekf/module.mk
+++ b/src/modules/attitude_estimator_ekf/module.mk
@@ -42,3 +42,7 @@ SRCS		 = attitude_estimator_ekf_main.cpp \
 		   codegen/AttitudeEKF.c
 
 MODULE_STACKSIZE = 1200
+
+EXTRACFLAGS = -Wno-float-equal -Wframe-larger-than=3600
+
+EXTRACXXFLAGS = -Wframe-larger-than=2400
diff --git a/src/modules/attitude_estimator_so3/attitude_estimator_so3_main.cpp b/src/modules/attitude_estimator_so3/attitude_estimator_so3_main.cpp
index e49027e47..9414225ca 100755
--- a/src/modules/attitude_estimator_so3/attitude_estimator_so3_main.cpp
+++ b/src/modules/attitude_estimator_so3/attitude_estimator_so3_main.cpp
@@ -153,7 +153,7 @@ int attitude_estimator_so3_main(int argc, char *argv[])
 					      SCHED_PRIORITY_MAX - 5,
 					      14000,
 					      attitude_estimator_so3_thread_main,
-					      (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					      (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/modules/attitude_estimator_so3/module.mk b/src/modules/attitude_estimator_so3/module.mk
index f52715abb..7b2e206cc 100644
--- a/src/modules/attitude_estimator_so3/module.mk
+++ b/src/modules/attitude_estimator_so3/module.mk
@@ -8,3 +8,5 @@ SRCS		 = attitude_estimator_so3_main.cpp \
 		   attitude_estimator_so3_params.c
 
 MODULE_STACKSIZE = 1200
+
+EXTRACXXFLAGS = -Wno-float-equal
diff --git a/src/modules/bottle_drop/bottle_drop.cpp b/src/modules/bottle_drop/bottle_drop.cpp
index 53ab74305..d8116ea11 100644
--- a/src/modules/bottle_drop/bottle_drop.cpp
+++ b/src/modules/bottle_drop/bottle_drop.cpp
@@ -524,6 +524,9 @@ BottleDrop::task_main()
 			}
 
 			switch (_drop_state) {
+				case DROP_STATE_INIT:
+					// do nothing
+					break;
 
 				case DROP_STATE_TARGET_VALID:
 				{
@@ -690,6 +693,10 @@ BottleDrop::task_main()
 						orb_publish(ORB_ID(onboard_mission), _onboard_mission_pub, &_onboard_mission);
 					}
 					break;
+
+				case DROP_STATE_BAY_CLOSED:
+					// do nothing
+					break;
 			}
 
 			counter++;
diff --git a/src/modules/commander/commander.cpp b/src/modules/commander/commander.cpp
index dca5c1a8e..dc0594bf2 100644
--- a/src/modules/commander/commander.cpp
+++ b/src/modules/commander/commander.cpp
@@ -268,7 +268,7 @@ int commander_main(int argc, char *argv[])
 					     SCHED_PRIORITY_MAX - 40,
 					     3200,
 					     commander_thread_main,
-					     (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					     (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 
 		while (!thread_running) {
 			usleep(200);
diff --git a/src/modules/commander/module.mk b/src/modules/commander/module.mk
index 27ca5c182..0e2a5356b 100644
--- a/src/modules/commander/module.mk
+++ b/src/modules/commander/module.mk
@@ -51,3 +51,6 @@ SRCS		 	= commander.cpp \
 MODULE_STACKSIZE = 1200
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACXXFLAGS = -Wframe-larger-than=2000
+
diff --git a/src/modules/ekf_att_pos_estimator/module.mk b/src/modules/ekf_att_pos_estimator/module.mk
index 36d854ddd..843dde978 100644
--- a/src/modules/ekf_att_pos_estimator/module.mk
+++ b/src/modules/ekf_att_pos_estimator/module.mk
@@ -42,4 +42,5 @@ SRCS		= ekf_att_pos_estimator_main.cpp \
 		  estimator_23states.cpp \
 		  estimator_utilities.cpp
 
-EXTRACXXFLAGS	= -Weffc++
+EXTRACXXFLAGS	= -Weffc++ -Wframe-larger-than=6100
+
diff --git a/src/modules/fixedwing_backside/fixedwing_backside_main.cpp b/src/modules/fixedwing_backside/fixedwing_backside_main.cpp
index f4ea05088..71b387b1e 100644
--- a/src/modules/fixedwing_backside/fixedwing_backside_main.cpp
+++ b/src/modules/fixedwing_backside/fixedwing_backside_main.cpp
@@ -115,7 +115,7 @@ int fixedwing_backside_main(int argc, char *argv[])
 					 SCHED_PRIORITY_MAX - 10,
 					 5120,
 					 control_demo_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/modules/fw_pos_control_l1/module.mk b/src/modules/fw_pos_control_l1/module.mk
index 440bab2c5..98e5c0a1e 100644
--- a/src/modules/fw_pos_control_l1/module.mk
+++ b/src/modules/fw_pos_control_l1/module.mk
@@ -47,3 +47,5 @@ SRCS		= fw_pos_control_l1_main.cpp \
 MODULE_STACKSIZE = 1200
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACXXFLAGS = -Wno-float-equal
diff --git a/src/modules/mavlink/mavlink_ftp.cpp b/src/modules/mavlink/mavlink_ftp.cpp
index f17497aa8..4ba595a87 100644
--- a/src/modules/mavlink/mavlink_ftp.cpp
+++ b/src/modules/mavlink/mavlink_ftp.cpp
@@ -801,7 +801,7 @@ MavlinkFTP::_return_request(Request *req)
 
 /// @brief Copy file (with limited space)
 int
-MavlinkFTP::_copy_file(const char *src_path, const char *dst_path, ssize_t length)
+MavlinkFTP::_copy_file(const char *src_path, const char *dst_path, size_t length)
 {
 	char buff[512];
 	int src_fd = -1, dst_fd = -1;
diff --git a/src/modules/mavlink/mavlink_ftp.h b/src/modules/mavlink/mavlink_ftp.h
index bef6775a9..9693a92a9 100644
--- a/src/modules/mavlink/mavlink_ftp.h
+++ b/src/modules/mavlink/mavlink_ftp.h
@@ -142,7 +142,7 @@ private:
 	static void	_worker_trampoline(void *arg);
 	void		_process_request(Request *req);
 	void		_reply(Request *req);
-	int		_copy_file(const char *src_path, const char *dst_path, ssize_t length);
+	int		_copy_file(const char *src_path, const char *dst_path, size_t length);
 
 	ErrorCode	_workList(PayloadHeader *payload);
 	ErrorCode	_workOpen(PayloadHeader *payload, int oflag);
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index 29b7ec7b7..f9a3681b3 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -948,7 +948,6 @@ Mavlink::configure_stream(const char *stream_name, const float rate)
 				/* delete stream */
 				LL_DELETE(_streams, stream);
 				delete stream;
-				warnx("deleted stream %s", stream->get_name());
 			}
 
 			return OK;
@@ -1412,9 +1411,13 @@ Mavlink::task_main(int argc, char *argv[])
 		configure_stream("SYS_STATUS", 1.0f);
 		configure_stream("ATTITUDE", 50.0f);
 		configure_stream("GLOBAL_POSITION_INT", 50.0f);
+		configure_stream("LOCAL_POSITION_NED", 30.0f);
 		configure_stream("CAMERA_CAPTURE", 2.0f);
 		configure_stream("ATTITUDE_TARGET", 10.0f);
 		configure_stream("POSITION_TARGET_GLOBAL_INT", 10.0f);
+		configure_stream("POSITION_TARGET_LOCAL_NED", 10.0f);
+		configure_stream("DISTANCE_SENSOR", 10.0f);
+		configure_stream("OPTICAL_FLOW_RAD", 10.0f);
 		configure_stream("VFR_HUD", 10.0f);
 		break;
 
@@ -1638,7 +1641,7 @@ Mavlink::start(int argc, char *argv[])
 		       SCHED_PRIORITY_DEFAULT,
 		       2800,
 		       (main_t)&Mavlink::start_helper,
-		       (const char **)argv);
+		       (char * const *)argv);
 
 	// Ensure that this shell command
 	// does not return before the instance
diff --git a/src/modules/mavlink/mavlink_messages.cpp b/src/modules/mavlink/mavlink_messages.cpp
index 378e3427d..0f25c969d 100644
--- a/src/modules/mavlink/mavlink_messages.cpp
+++ b/src/modules/mavlink/mavlink_messages.cpp
@@ -1486,6 +1486,7 @@ protected:
 		if (_pos_sp_triplet_sub->update(&pos_sp_triplet)) {
 			mavlink_position_target_global_int_t msg{};
 
+			msg.time_boot_ms = hrt_absolute_time()/1000;
 			msg.coordinate_frame = MAV_FRAME_GLOBAL;
 			msg.lat_int = pos_sp_triplet.current.lat * 1e7;
 			msg.lon_int = pos_sp_triplet.current.lon * 1e7;
@@ -1764,6 +1765,9 @@ protected:
 				case RC_INPUT_SOURCE_PX4IO_ST24:
 					msg.rssi |= (3 << 4);
 					break;
+				case RC_INPUT_SOURCE_UNKNOWN:
+					// do nothing
+					break;
 			}
 
 			if (rc.rc_lost) {
diff --git a/src/modules/mavlink/module.mk b/src/modules/mavlink/module.mk
index 91fdd6154..f9d30dcbe 100644
--- a/src/modules/mavlink/module.mk
+++ b/src/modules/mavlink/module.mk
@@ -53,4 +53,6 @@ MAXOPTIMIZATION	 = -Os
 
 MODULE_STACKSIZE = 1024
 
-EXTRACXXFLAGS	= -Weffc++
+EXTRACXXFLAGS	= -Weffc++ -Wno-attributes -Wno-packed
+
+EXTRACFLAGS	= -Wno-packed
diff --git a/src/modules/navigator/module.mk b/src/modules/navigator/module.mk
index c44d4c35e..0d7d6b9ef 100644
--- a/src/modules/navigator/module.mk
+++ b/src/modules/navigator/module.mk
@@ -62,3 +62,5 @@ INCLUDE_DIRS	 += $(MAVLINK_SRC)/include/mavlink
 MODULE_STACKSIZE = 1200
 
 MAXOPTIMIZATION = -Os
+
+EXTRACXXFLAGS	= -Wno-sign-compare
diff --git a/src/modules/position_estimator_inav/module.mk b/src/modules/position_estimator_inav/module.mk
index 0658d3f09..45c876299 100644
--- a/src/modules/position_estimator_inav/module.mk
+++ b/src/modules/position_estimator_inav/module.mk
@@ -41,3 +41,6 @@ SRCS		 	= position_estimator_inav_main.c \
 			inertial_filter.c
 
 MODULE_STACKSIZE = 1200
+
+EXTRACFLAGS = -Wframe-larger-than=3500
+
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 4bdb4d539..6fb87ae7e 100644
--- a/src/modules/position_estimator_inav/position_estimator_inav_main.c
+++ b/src/modules/position_estimator_inav/position_estimator_inav_main.c
@@ -152,7 +152,7 @@ int position_estimator_inav_main(int argc, char *argv[])
 		position_estimator_inav_task = task_spawn_cmd("position_estimator_inav",
 					       SCHED_DEFAULT, SCHED_PRIORITY_MAX - 5, 5000,
 					       position_estimator_inav_thread_main,
-					       (argv) ? (const char **) &argv[2] : (const char **) NULL);
+					       (argv) ? (char * const *) &argv[2] : (char * const *) NULL);
 		exit(0);
 	}
 
@@ -234,8 +234,8 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 
 	float eph_flow = 1.0f;
 
-	float eph_vision = 0.5f;
-	float epv_vision = 0.5f;
+	float eph_vision = 0.2f;
+	float epv_vision = 0.2f;
 
 	float x_est_prev[2], y_est_prev[2], z_est_prev[2];
 	memset(x_est_prev, 0, sizeof(x_est_prev));
@@ -641,6 +641,10 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 				if (updated) {
 					orb_copy(ORB_ID(vision_position_estimate), vision_position_estimate_sub, &vision);
 
+					static float last_vision_x = 0.0f;
+					static float last_vision_y = 0.0f;
+					static float last_vision_z = 0.0f;
+
 					/* reset position estimate on first vision update */
 					if (!vision_valid) {
 						x_est[0] = vision.x;
@@ -655,6 +659,11 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 						}
 
 						vision_valid = true;
+
+						last_vision_x = vision.x;
+						last_vision_y = vision.y;
+						last_vision_z = vision.z;
+
 						warnx("VISION estimate valid");
 						mavlink_log_info(mavlink_fd, "[inav] VISION estimate valid");
 					}
@@ -664,10 +673,30 @@ int position_estimator_inav_thread_main(int argc, char *argv[])
 					corr_vision[1][0] = vision.y - y_est[0];
 					corr_vision[2][0] = vision.z - z_est[0];
 
-					/* calculate correction for velocity */
-					corr_vision[0][1] = vision.vx - x_est[1];
-					corr_vision[1][1] = vision.vy - y_est[1];
-					corr_vision[2][1] = vision.vz - z_est[1];
+					static hrt_abstime last_vision_time = 0;
+
+					float vision_dt = (vision.timestamp_boot - last_vision_time) / 1e6f;
+					last_vision_time = vision.timestamp_boot;
+
+					if (vision_dt > 0.000001f && vision_dt < 0.2f) {
+						vision.vx = (vision.x - last_vision_x) / vision_dt;
+						vision.vy = (vision.y - last_vision_y) / vision_dt;
+						vision.vz = (vision.z - last_vision_z) / vision_dt;
+
+						last_vision_x = vision.x;
+						last_vision_y = vision.y;
+						last_vision_z = vision.z;
+
+						/* calculate correction for velocity */
+						corr_vision[0][1] = vision.vx - x_est[1];
+						corr_vision[1][1] = vision.vy - y_est[1];
+						corr_vision[2][1] = vision.vz - z_est[1];
+					} else {
+						/* assume zero motion */
+						corr_vision[0][1] = 0.0f - x_est[1];
+						corr_vision[1][1] = 0.0f - y_est[1];
+						corr_vision[2][1] = 0.0f - z_est[1];
+					}
 
 				}
 			}
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 cc0fb4155..b7f6509d7 100644
--- a/src/modules/position_estimator_inav/position_estimator_inav_params.c
+++ b/src/modules/position_estimator_inav/position_estimator_inav_params.c
@@ -116,7 +116,7 @@ PARAM_DEFINE_FLOAT(INAV_W_XY_GPS_V, 2.0f);
  * @max 10.0
  * @group Position Estimator INAV
  */
-PARAM_DEFINE_FLOAT(INAV_W_XY_VIS_P, 5.0f);
+PARAM_DEFINE_FLOAT(INAV_W_XY_VIS_P, 7.0f);
 
 /**
  * XY axis weight for vision velocity
diff --git a/src/modules/sdlog2/module.mk b/src/modules/sdlog2/module.mk
index d4a00af39..f1118000e 100644
--- a/src/modules/sdlog2/module.mk
+++ b/src/modules/sdlog2/module.mk
@@ -45,3 +45,6 @@ SRCS = sdlog2.c \
 MODULE_STACKSIZE = 1200
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACFLAGS = -Wframe-larger-than=1200
+
diff --git a/src/modules/sdlog2/sdlog2.c b/src/modules/sdlog2/sdlog2.c
index 6df677338..0a8564da6 100644
--- a/src/modules/sdlog2/sdlog2.c
+++ b/src/modules/sdlog2/sdlog2.c
@@ -304,7 +304,7 @@ int sdlog2_main(int argc, char *argv[])
 						 SCHED_PRIORITY_DEFAULT - 30,
 						 3000,
 						 sdlog2_thread_main,
-						 (const char **)argv);
+						 (char * const *)argv);
 		exit(0);
 	}
 
@@ -1089,6 +1089,8 @@ int sdlog2_thread_main(int argc, char *argv[])
 
 	if (_extended_logging) {
 		subs.sat_info_sub = orb_subscribe(ORB_ID(satellite_info));
+	} else {
+		subs.sat_info_sub = 0;
 	}
 
 	/* close non-needed fd's */
diff --git a/src/modules/sdlog2/sdlog2_messages.h b/src/modules/sdlog2/sdlog2_messages.h
index b78b430aa..5b047f538 100644
--- a/src/modules/sdlog2/sdlog2_messages.h
+++ b/src/modules/sdlog2/sdlog2_messages.h
@@ -468,7 +468,7 @@ static const struct log_format_s log_formats[] = {
 	LOG_FORMAT(OUT0, "ffffffff",		"Out0,Out1,Out2,Out3,Out4,Out5,Out6,Out7"),
 	LOG_FORMAT(AIRS, "fff",			"IndSpeed,TrueSpeed,AirTemp"),
 	LOG_FORMAT(ARSP, "fff",			"RollRateSP,PitchRateSP,YawRateSP"),
-	LOG_FORMAT(FLOW, "hhfffBB",		"RawX,RawY,CompX,CompY,Dist,Q,SensID"),
+	LOG_FORMAT(FLOW, "QBffffffLLHhB",	"IntT,ID,RawX,RawY,RX,RY,RZ,Dist,TSpan,DtSonar,FrmCnt,GT,Qlty"),
 	LOG_FORMAT(GPOS, "LLfffffff",		"Lat,Lon,Alt,VelN,VelE,VelD,EPH,EPV,TALT"),
 	LOG_FORMAT(GPSP, "BLLffBfbf",		"NavState,Lat,Lon,Alt,Yaw,Type,LoitR,LoitDir,PitMin"),
 	LOG_FORMAT(ESC, "HBBBHHffiffH",		"count,nESC,Conn,N,Ver,Adr,Volt,Amp,RPM,Temp,SetP,SetPRAW"),
diff --git a/src/modules/segway/segway_main.cpp b/src/modules/segway/segway_main.cpp
index 061fbf9b9..ee492f85a 100644
--- a/src/modules/segway/segway_main.cpp
+++ b/src/modules/segway/segway_main.cpp
@@ -110,7 +110,7 @@ int segway_main(int argc, char *argv[])
 					 SCHED_PRIORITY_MAX - 10,
 					 5120,
 					 segway_thread_main,
-					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+					 (argv) ? (char * const *)&argv[2] : (char * const *)NULL);
 		exit(0);
 	}
 
diff --git a/src/modules/sensors/module.mk b/src/modules/sensors/module.mk
index dfbba92d9..f37bc9327 100644
--- a/src/modules/sensors/module.mk
+++ b/src/modules/sensors/module.mk
@@ -44,3 +44,5 @@ SRCS		= sensors.cpp \
 MODULE_STACKSIZE = 1200
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACXXFLAGS	= -Wno-type-limits
diff --git a/src/modules/systemlib/module.mk b/src/modules/systemlib/module.mk
index 1e0a9c007..f2499bbb1 100644
--- a/src/modules/systemlib/module.mk
+++ b/src/modules/systemlib/module.mk
@@ -58,3 +58,5 @@ SRCS		 = err.c \
 		   mcu_version.c
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACFLAGS	= -Wno-sign-compare
diff --git a/src/modules/systemlib/system_params.c b/src/modules/systemlib/system_params.c
index 702e435ac..a0988035c 100644
--- a/src/modules/systemlib/system_params.c
+++ b/src/modules/systemlib/system_params.c
@@ -82,3 +82,17 @@ PARAM_DEFINE_INT32(SYS_USE_IO, 1);
 * @group System
 */
 PARAM_DEFINE_INT32(SYS_RESTART_TYPE, 2);
+
+/**
+* Companion computer interface
+*
+* Configures the baud rate of the companion computer interface.
+* Set to zero to disable, set to 921600 to enable.
+* CURRENTLY ONLY SUPPORTS 921600 BAUD! Use extras.txt for
+* other baud rates.
+*
+* @min 0
+* @max 921600
+* @group System
+*/
+PARAM_DEFINE_INT32(SYS_COMPANION, 0);
diff --git a/src/modules/systemlib/systemlib.c b/src/modules/systemlib/systemlib.c
index 90d8dd77c..82183b0d7 100644
--- a/src/modules/systemlib/systemlib.c
+++ b/src/modules/systemlib/systemlib.c
@@ -87,7 +87,7 @@ static void kill_task(FAR struct tcb_s *tcb, FAR void *arg)
 	kill(tcb->pid, SIGUSR1);
 }
 
-int task_spawn_cmd(const char *name, int scheduler, int priority, int stack_size, main_t entry, const char *argv[])
+int task_spawn_cmd(const char *name, int scheduler, int priority, int stack_size, main_t entry, char * const argv[])
 {
 	int pid;
 
diff --git a/src/modules/systemlib/systemlib.h b/src/modules/systemlib/systemlib.h
index 6e22a557e..2f24215a9 100644
--- a/src/modules/systemlib/systemlib.h
+++ b/src/modules/systemlib/systemlib.h
@@ -64,7 +64,7 @@ __EXPORT int task_spawn_cmd(const char *name,
 			int scheduler,
 			int stack_size,
 			main_t entry,
-			const char *argv[]);
+			char * const argv[]);
 
 enum MULT_PORTS {
 	MULT_0_US2_RXTX = 0,
diff --git a/src/modules/uORB/uORB.h b/src/modules/uORB/uORB.h
index a6e9171ed..707ff1efd 100644
--- a/src/modules/uORB/uORB.h
+++ b/src/modules/uORB/uORB.h
@@ -68,6 +68,33 @@ typedef const struct orb_metadata *orb_id_t;
 #define ORB_ID(_name)		&__orb_##_name
 
 /**
+ * Generates a pointer to the uORB metadata structure for
+ * a given topic.
+ *
+ * The topic must have been declared previously in scope
+ * with ORB_DECLARE().
+ *
+ * @param _name		The name of the topic.
+ * @param _count	The class ID of the topic
+ */
+#define ORB_ID_DOUBLE(_name, _count)	((_count == CLASS_DEVICE_PRIMARY) ? &__orb_##_name##0 : &__orb_##_name##1)
+
+/**
+ * Generates a pointer to the uORB metadata structure for
+ * a given topic.
+ *
+ * The topic must have been declared previously in scope
+ * with ORB_DECLARE().
+ *
+ * @param _name		The name of the topic.
+ * @param _count	The class ID of the topic
+ */
+#define ORB_ID_TRIPLE(_name, _count)					\
+ 	((_count == CLASS_DEVICE_PRIMARY) ? &__orb_##_name##0 : \
+			((_count == CLASS_DEVICE_SECONDARY) ? &__orb_##_name##1 : \
+				(((_count == CLASS_DEVICE_TERTIARY) ? &__orb_##_name##2 : 0))))
+
+/**
  * Declare (prototype) the uORB metadata for a topic.
  *
  * Note that optional topics are declared weak; this allows a potential
diff --git a/src/modules/vtol_att_control/module.mk b/src/modules/vtol_att_control/module.mk
index 0d5155e90..0cf3072c8 100644
--- a/src/modules/vtol_att_control/module.mk
+++ b/src/modules/vtol_att_control/module.mk
@@ -39,3 +39,6 @@ MODULE_COMMAND	= vtol_att_control
 
 SRCS		= vtol_att_control_main.cpp \
 			  vtol_att_control_params.c
+
+EXTRACXXFLAGS = -Wno-write-strings
+
diff --git a/src/systemcmds/bl_update/bl_update.c b/src/systemcmds/bl_update/bl_update.c
index 0569d89f5..ec9269d39 100644
--- a/src/systemcmds/bl_update/bl_update.c
+++ b/src/systemcmds/bl_update/bl_update.c
@@ -52,6 +52,8 @@
 #include "systemlib/systemlib.h"
 #include "systemlib/err.h"
 
+#define BL_FILE_SIZE_LIMIT	16384
+
 __EXPORT int bl_update_main(int argc, char *argv[]);
 
 static void setopt(void);
@@ -72,12 +74,12 @@ bl_update_main(int argc, char *argv[])
 
 	struct stat s;
 
-	if (stat(argv[1], &s) < 0)
+	if (!stat(argv[1], &s))
 		err(1, "stat %s", argv[1]);
 
 	/* sanity-check file size */
-	if (s.st_size > 16384)
-		errx(1, "%s: file too large", argv[1]);
+	if (s.st_size > BL_FILE_SIZE_LIMIT)
+		errx(1, "%s: file too large (limit: %u, actual: %d)", argv[1], BL_FILE_SIZE_LIMIT, s.st_size);
 
 	uint8_t *buf = malloc(s.st_size);
 
diff --git a/src/systemcmds/mixer/module.mk b/src/systemcmds/mixer/module.mk
index cdbff75f0..0fb899c67 100644
--- a/src/systemcmds/mixer/module.mk
+++ b/src/systemcmds/mixer/module.mk
@@ -41,3 +41,6 @@ SRCS		 = mixer.cpp
 MODULE_STACKSIZE = 4096
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACXXFLAGS = -Wframe-larger-than=2048
+
diff --git a/src/systemcmds/mtd/module.mk b/src/systemcmds/mtd/module.mk
index 1bc4f414e..bca1cdcc1 100644
--- a/src/systemcmds/mtd/module.mk
+++ b/src/systemcmds/mtd/module.mk
@@ -6,3 +6,6 @@ MODULE_COMMAND	 = mtd
 SRCS		 = mtd.c 24xxxx_mtd.c
 
 MAXOPTIMIZATION	 = -Os
+
+EXTRACFLAGS	= -Wno-error
+
diff --git a/src/systemcmds/param/param.c b/src/systemcmds/param/param.c
index e110335e7..80ee204e8 100644
--- a/src/systemcmds/param/param.c
+++ b/src/systemcmds/param/param.c
@@ -212,7 +212,7 @@ static void
 do_show(const char* search_string)
 {
 	printf(" + = saved, * = unsaved\n");
-	param_foreach(do_show_print, search_string, false);
+	param_foreach(do_show_print, (char *)search_string, false);
 
 	exit(0);
 }
diff --git a/src/systemcmds/tests/module.mk b/src/systemcmds/tests/module.mk
index 622a0faf3..6eed3922c 100644
--- a/src/systemcmds/tests/module.mk
+++ b/src/systemcmds/tests/module.mk
@@ -34,3 +34,6 @@ SRCS			 = test_adc.c \
 			   test_conv.cpp \
 			   test_mount.c \
 			   test_mtd.c
+
+EXTRACXXFLAGS = -Wframe-larger-than=2500
+
diff --git a/unittests/.gitignore b/unittests/.gitignore
index 37e923b5e..aa316941f 100644
--- a/unittests/.gitignore
+++ b/unittests/.gitignore
@@ -1,6 +1,8 @@
 ./obj/*
+gtest_main.a
 mixer_test
 sf0x_test
 sbus2_test
 autodeclination_test
 st24_test
+sample_unittest
diff --git a/unittests/Makefile b/unittests/Makefile
index dfd5ccb3f..e55411a75 100644
--- a/unittests/Makefile
+++ b/unittests/Makefile
@@ -3,7 +3,44 @@ CC=g++
 CFLAGS=-I. -I../src/modules -I ../src/include -I../src/drivers \
 	-I../src -I../src/lib -D__EXPORT="" -Dnullptr="0" -lm
 
-all: mixer_test sbus2_test autodeclination_test st24_test sf0x_test
+# Points to the root of Google Test, relative to where this file is.
+# Remember to tweak this if you move this file.
+GTEST_DIR = gtest
+
+# Flags passed to the preprocessor.
+# Set Google Test's header directory as a system directory, such that
+# the compiler doesn't generate warnings in Google Test headers.
+CFLAGS += -isystem $(GTEST_DIR)/include
+
+# All Google Test headers.  Usually you shouldn't change this
+# definition.
+GTEST_HEADERS = $(GTEST_DIR)/include/gtest/*.h \
+                $(GTEST_DIR)/include/gtest/internal/*.h
+
+# Usually you shouldn't tweak such internal variables, indicated by a
+# trailing _.
+GTEST_SRCS_ = $(GTEST_DIR)/src/*.cc $(GTEST_DIR)/src/*.h $(GTEST_HEADERS)
+
+# For simplicity and to avoid depending on Google Test's
+# implementation details, the dependencies specified below are
+# conservative and not optimized.  This is fine as Google Test
+# compiles fast and for ordinary users its source rarely changes.
+gtest-all.o: $(GTEST_SRCS_)
+	$(CC) $(CFLAGS) -I$(GTEST_DIR) -c \
+            $(GTEST_DIR)/src/gtest-all.cc
+
+gtest_main.o: $(GTEST_SRCS_)
+	$(CC) $(CFLAGS) -I$(GTEST_DIR) -c \
+            $(GTEST_DIR)/src/gtest_main.cc
+
+gtest.a: gtest-all.o
+	$(AR) $(ARFLAGS) $@ $^
+
+gtest_main.a: gtest-all.o gtest_main.o
+	$(AR) $(ARFLAGS) $@ $^
+
+
+all: sample_unittest mixer_test sbus2_test autodeclination_test st24_test sf0x_test
 
 MIXER_FILES=../src/systemcmds/tests/test_mixer.cpp \
 		../src/systemcmds/tests/test_conv.cpp \
@@ -33,6 +70,20 @@ AUTODECLINATION_FILES= ../src/lib/geo_lookup/geo_mag_declination.c \
 		hrt.cpp \
 		autodeclination_test.cpp
 
+# Builds a sample test. A test should link with either gtest.a or
+# gtest_main.a, depending on whether it defines its own main()
+# function.
+sample.o: sample.cc sample.h $(GTEST_HEADERS)
+	$(CC) $(CFLAGS) -c sample.cc
+
+sample_unittest.o: sample_unittest.cc \
+                     sample.h $(GTEST_HEADERS)
+	$(CC) $(CFLAGS) -c sample_unittest.cc
+
+sample_unittest: sample.o sample_unittest.o gtest_main.a
+	$(CC) $(CFLAGS) $^ -o $@
+
+
 mixer_test: $(MIXER_FILES)
 	$(CC) -o mixer_test $(MIXER_FILES) $(CFLAGS)
 
@@ -57,4 +108,4 @@ unittests: clean mixer_test sbus2_test sf0x_test autodeclination_test st24_test
 
 .PHONY: clean
 clean:
-	rm -f $(ODIR)/*.o *~ core $(INCDIR)/*~ mixer_test sbus2_test autodeclination_test st24_test sf0x_test
+	rm -f gtest.a gtest_main.a *.o $(ODIR)/*.o *~ core $(INCDIR)/*~ sample_unittest mixer_test sbus2_test autodeclination_test st24_test sf0x_test
diff --git a/unittests/gtest b/unittests/gtest
new file mode 160000
+Subproject cdef6e4ce097f953445446e8da4cb8bb68478bc
diff --git a/unittests/sample.cc b/unittests/sample.cc
new file mode 100644
index 000000000..3f0c838f2
--- /dev/null
+++ b/unittests/sample.cc
@@ -0,0 +1,68 @@
+// Copyright 2005, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * 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.
+//     * Neither the name of Google Inc. 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.
+
+// A sample program demonstrating using Google C++ testing framework.
+//
+// Author: wan@google.com (Zhanyong Wan)
+
+#include "sample.h"
+
+// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
+int Factorial(int n) {
+  int result = 1;
+  for (int i = 1; i <= n; i++) {
+    result *= i;
+  }
+
+  return result;
+}
+
+// Returns true iff n is a prime number.
+bool IsPrime(int n) {
+  // Trivial case 1: small numbers
+  if (n <= 1) return false;
+
+  // Trivial case 2: even numbers
+  if (n % 2 == 0) return n == 2;
+
+  // Now, we have that n is odd and n >= 3.
+
+  // Try to divide n by every odd number i, starting from 3
+  for (int i = 3; ; i += 2) {
+    // We only have to try i up to the squre root of n
+    if (i > n/i) break;
+
+    // Now, we have i <= n/i < n.
+    // If n is divisible by i, n is not prime.
+    if (n % i == 0) return false;
+  }
+
+  // n has no integer factor in the range (1, n), and thus is prime.
+  return true;
+}
diff --git a/unittests/sample.h b/unittests/sample.h
new file mode 100644
index 000000000..3dfeb98c4
--- /dev/null
+++ b/unittests/sample.h
@@ -0,0 +1,43 @@
+// Copyright 2005, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * 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.
+//     * Neither the name of Google Inc. 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.
+
+// A sample program demonstrating using Google C++ testing framework.
+//
+// Author: wan@google.com (Zhanyong Wan)
+
+#ifndef GTEST_SAMPLES_SAMPLE1_H_
+#define GTEST_SAMPLES_SAMPLE1_H_
+
+// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
+int Factorial(int n);
+
+// Returns true iff n is a prime number.
+bool IsPrime(int n);
+
+#endif  // GTEST_SAMPLES_SAMPLE1_H_
diff --git a/unittests/sample_unittest.cc b/unittests/sample_unittest.cc
new file mode 100644
index 000000000..8dc3f5c38
--- /dev/null
+++ b/unittests/sample_unittest.cc
@@ -0,0 +1,153 @@
+// Copyright 2005, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * 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.
+//     * Neither the name of Google Inc. 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.
+
+// A sample program demonstrating using Google C++ testing framework.
+//
+// Author: wan@google.com (Zhanyong Wan)
+
+
+// This sample shows how to write a simple unit test for a function,
+// using Google C++ testing framework.
+//
+// Writing a unit test using Google C++ testing framework is easy as 1-2-3:
+
+
+// Step 1. Include necessary header files such that the stuff your
+// test logic needs is declared.
+//
+// Don't forget gtest.h, which declares the testing framework.
+
+#include <limits.h>
+#include "sample.h"
+#include "gtest/gtest.h"
+
+
+// Step 2. Use the TEST macro to define your tests.
+//
+// TEST has two parameters: the test case name and the test name.
+// After using the macro, you should define your test logic between a
+// pair of braces.  You can use a bunch of macros to indicate the
+// success or failure of a test.  EXPECT_TRUE and EXPECT_EQ are
+// examples of such macros.  For a complete list, see gtest.h.
+//
+// <TechnicalDetails>
+//
+// In Google Test, tests are grouped into test cases.  This is how we
+// keep test code organized.  You should put logically related tests
+// into the same test case.
+//
+// The test case name and the test name should both be valid C++
+// identifiers.  And you should not use underscore (_) in the names.
+//
+// Google Test guarantees that each test you define is run exactly
+// once, but it makes no guarantee on the order the tests are
+// executed.  Therefore, you should write your tests in such a way
+// that their results don't depend on their order.
+//
+// </TechnicalDetails>
+
+
+// Tests Factorial().
+
+// Tests factorial of negative numbers.
+TEST(FactorialTest, Negative) {
+  // This test is named "Negative", and belongs to the "FactorialTest"
+  // test case.
+  EXPECT_EQ(1, Factorial(-5));
+  EXPECT_EQ(1, Factorial(-1));
+  EXPECT_GT(Factorial(-10), 0);
+
+  // <TechnicalDetails>
+  //
+  // EXPECT_EQ(expected, actual) is the same as
+  //
+  //   EXPECT_TRUE((expected) == (actual))
+  //
+  // except that it will print both the expected value and the actual
+  // value when the assertion fails.  This is very helpful for
+  // debugging.  Therefore in this case EXPECT_EQ is preferred.
+  //
+  // On the other hand, EXPECT_TRUE accepts any Boolean expression,
+  // and is thus more general.
+  //
+  // </TechnicalDetails>
+}
+
+// Tests factorial of 0.
+TEST(FactorialTest, Zero) {
+  EXPECT_EQ(1, Factorial(0));
+}
+
+// Tests factorial of positive numbers.
+TEST(FactorialTest, Positive) {
+  EXPECT_EQ(1, Factorial(1));
+  EXPECT_EQ(2, Factorial(2));
+  EXPECT_EQ(6, Factorial(3));
+  EXPECT_EQ(40320, Factorial(8));
+}
+
+
+// Tests IsPrime()
+
+// Tests negative input.
+TEST(IsPrimeTest, Negative) {
+  // This test belongs to the IsPrimeTest test case.
+
+  EXPECT_FALSE(IsPrime(-1));
+  EXPECT_FALSE(IsPrime(-2));
+  EXPECT_FALSE(IsPrime(INT_MIN));
+}
+
+// Tests some trivial cases.
+TEST(IsPrimeTest, Trivial) {
+  EXPECT_FALSE(IsPrime(0));
+  EXPECT_FALSE(IsPrime(1));
+  EXPECT_TRUE(IsPrime(2));
+  EXPECT_TRUE(IsPrime(3));
+}
+
+// Tests positive input.
+TEST(IsPrimeTest, Positive) {
+  EXPECT_FALSE(IsPrime(4));
+  EXPECT_TRUE(IsPrime(5));
+  EXPECT_FALSE(IsPrime(6));
+  EXPECT_TRUE(IsPrime(23));
+}
+
+// Step 3. Call RUN_ALL_TESTS() in main().
+//
+// We do this by linking in src/gtest_main.cc file, which consists of
+// a main() function which calls RUN_ALL_TESTS() for us.
+//
+// This runs all the tests you've defined, prints the result, and
+// returns 0 if successful, or 1 otherwise.
+//
+// Did you notice that we didn't register the tests?  The
+// RUN_ALL_TESTS() macro magically knows about all the tests we
+// defined.  Isn't this convenient?