Merge branch 'master' into fmuv2_bringup

22 files changed, 3045 insertions, 37 deletions

diff --git a/src/modules/att_pos_estimator_ekf/KalmanNav.cpp b/src/modules/att_pos_estimator_ekf/KalmanNav.cpp
index 4ef150da1..c3836bdfa 100644
--- a/src/modules/att_pos_estimator_ekf/KalmanNav.cpp
+++ b/src/modules/att_pos_estimator_ekf/KalmanNav.cpp
@@ -683,7 +683,8 @@ int KalmanNav::correctPos()
 	// fault detetcion
 	float beta = y.dot(S.inverse() * y);
 
-	if (beta > _faultPos.get()) {
+	static int counter = 0;
+	if (beta > _faultPos.get() && (counter % 10 == 0)) {
 		printf("fault in gps: beta = %8.4f\n", (double)beta);
 		printf("Y/N: vN: %8.4f, vE: %8.4f, lat: %8.4f, lon: %8.4f, alt: %8.4f\n",
 		       double(y(0) / sqrtf(RPos(0, 0))),
@@ -693,6 +694,7 @@ int KalmanNav::correctPos()
 		       double(y(4) / sqrtf(RPos(4, 4))),
 		       double(y(5) / sqrtf(RPos(5, 5))));
 	}
+	counter++;
 
 	return ret_ok;
 }
diff --git a/src/modules/att_pos_estimator_ekf/kalman_main.cpp b/src/modules/att_pos_estimator_ekf/kalman_main.cpp
index aebe3d1fe..10592ec7c 100644
--- a/src/modules/att_pos_estimator_ekf/kalman_main.cpp
+++ b/src/modules/att_pos_estimator_ekf/kalman_main.cpp
@@ -44,6 +44,7 @@
 #include <string.h>
 #include <systemlib/systemlib.h>
 #include <systemlib/param/param.h>
+#include <systemlib/err.h>
 #include <drivers/drv_hrt.h>
 #include <math.h>
 #include "KalmanNav.hpp"
@@ -73,7 +74,7 @@ usage(const char *reason)
 	if (reason)
 		fprintf(stderr, "%s\n", reason);
 
-	fprintf(stderr, "usage: kalman_demo {start|stop|status} [-p <additional params>]\n\n");
+	warnx("usage: att_pos_estimator_ekf {start|stop|status} [-p <additional params>]");
 	exit(1);
 }
 
@@ -94,13 +95,13 @@ int att_pos_estimator_ekf_main(int argc, char *argv[])
 	if (!strcmp(argv[1], "start")) {
 
 		if (thread_running) {
-			printf("kalman_demo already running\n");
+			warnx("already running");
 			/* this is not an error */
 			exit(0);
 		}
 
 		thread_should_exit = false;
-		deamon_task = task_spawn("kalman_demo",
+		deamon_task = task_spawn("att_pos_estimator_ekf",
 					 SCHED_DEFAULT,
 					 SCHED_PRIORITY_MAX - 5,
 					 4096,
@@ -116,10 +117,10 @@ int att_pos_estimator_ekf_main(int argc, char *argv[])
 
 	if (!strcmp(argv[1], "status")) {
 		if (thread_running) {
-			printf("\tkalman_demo app is running\n");
+			warnx("is running\n");
 
 		} else {
-			printf("\tkalman_demo app not started\n");
+			warnx("not started\n");
 		}
 
 		exit(0);
@@ -132,7 +133,7 @@ int att_pos_estimator_ekf_main(int argc, char *argv[])
 int kalman_demo_thread_main(int argc, char *argv[])
 {
 
-	printf("[kalman_demo] starting\n");
+	warnx("starting\n");
 
 	using namespace math;
 
@@ -144,7 +145,7 @@ int kalman_demo_thread_main(int argc, char *argv[])
 		nav.update();
 	}
 
-	printf("[kalman_demo] exiting.\n");
+	printf("exiting.\n");
 
 	thread_running = false;
 
diff --git a/src/modules/attitude_estimator_so3_comp/README b/src/modules/attitude_estimator_so3_comp/README
new file mode 100644
index 000000000..79c50a531
--- /dev/null
+++ b/src/modules/attitude_estimator_so3_comp/README
@@ -0,0 +1,5 @@
+Synopsis
+
+ nsh> attitude_estimator_so3_comp start -d /dev/ttyS1 -b 115200
+
+Option -d is for debugging packet. See code for detailed packet structure.
diff --git a/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_main.cpp b/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_main.cpp
new file mode 100755
index 000000000..3cbc62ea1
--- /dev/null
+++ b/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_main.cpp
@@ -0,0 +1,833 @@
+/*
+ * Author: Hyon Lim <limhyon@gmail.com, hyonlim@snu.ac.kr>
+ *
+ * @file attitude_estimator_so3_comp_main.c
+ *
+ * Implementation of nonlinear complementary filters on the SO(3).
+ * This code performs attitude estimation by using accelerometer, gyroscopes and magnetometer.
+ * Result is provided as quaternion, 1-2-3 Euler angle and rotation matrix.
+ * 
+ * Theory of nonlinear complementary filters on the SO(3) is based on [1].
+ * Quaternion realization of [1] is based on [2].
+ * Optmized quaternion update code is based on Sebastian Madgwick's implementation.
+ * 
+ * References
+ *  [1] Mahony, R.; Hamel, T.; Pflimlin, Jean-Michel, "Nonlinear Complementary Filters on the Special Orthogonal Group," Automatic Control, IEEE Transactions on , vol.53, no.5, pp.1203,1218, June 2008
+ *  [2] Euston, M.; Coote, P.; Mahony, R.; Jonghyuk Kim; Hamel, T., "A complementary filter for attitude estimation of a fixed-wing UAV," Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on , vol., no., pp.340,345, 22-26 Sept. 2008
+ */
+
+#include <nuttx/config.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <float.h>
+#include <nuttx/sched.h>
+#include <sys/prctl.h>
+#include <termios.h>
+#include <errno.h>
+#include <limits.h>
+#include <math.h>
+#include <uORB/uORB.h>
+#include <uORB/topics/debug_key_value.h>
+#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/vehicle_attitude.h>
+#include <uORB/topics/vehicle_status.h>
+#include <uORB/topics/parameter_update.h>
+#include <drivers/drv_hrt.h>
+
+#include <systemlib/systemlib.h>
+#include <systemlib/perf_counter.h>
+#include <systemlib/err.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+#include "attitude_estimator_so3_comp_params.h"
+#ifdef __cplusplus
+}
+#endif
+
+extern "C" __EXPORT int attitude_estimator_so3_comp_main(int argc, char *argv[]);
+
+static bool thread_should_exit = false;		/**< Deamon exit flag */
+static bool thread_running = false;		/**< Deamon status flag */
+static int attitude_estimator_so3_comp_task;				/**< Handle of deamon task / thread */
+static float q0 = 1.0f, q1 = 0.0f, q2 = 0.0f, q3 = 0.0f;	/** quaternion of sensor frame relative to auxiliary frame */
+static float dq0 = 0.0f, dq1 = 0.0f, dq2 = 0.0f, dq3 = 0.0f;	/** quaternion of sensor frame relative to auxiliary frame */
+static float gyro_bias[3] = {0.0f, 0.0f, 0.0f}; /** bias estimation */
+static bool bFilterInit = false;
+
+//! Auxiliary variables to reduce number of repeated operations
+static float q0q0, q0q1, q0q2, q0q3;
+static float q1q1, q1q2, q1q3;
+static float q2q2, q2q3;
+static float q3q3;
+
+//! Serial packet related
+static int uart;
+static int baudrate;
+
+/**
+ * Mainloop of attitude_estimator_so3_comp.
+ */
+int attitude_estimator_so3_comp_thread_main(int argc, char *argv[]);
+
+/**
+ * Print the correct usage.
+ */
+static void usage(const char *reason);
+
+static void
+usage(const char *reason)
+{
+	if (reason)
+		fprintf(stderr, "%s\n", reason);
+
+	fprintf(stderr, "usage: attitude_estimator_so3_comp {start|stop|status} [-d <devicename>] [-b <baud rate>]\n"
+		"-d and -b options are for separate visualization with raw data (quaternion packet) transfer\n"
+		"ex) attitude_estimator_so3_comp start -d /dev/ttyS1 -b 115200\n");
+	exit(1);
+}
+
+/**
+ * The attitude_estimator_so3_comp app only briefly exists to start
+ * the background job. The stack size assigned in the
+ * Makefile does only apply to this management task.
+ *
+ * The actual stack size should be set in the call
+ * to task_create().
+ */
+int attitude_estimator_so3_comp_main(int argc, char *argv[])
+{
+	if (argc < 1)
+		usage("missing command");
+
+	
+
+	if (!strcmp(argv[1], "start")) {
+
+		if (thread_running) {
+			printf("attitude_estimator_so3_comp already running\n");
+			/* this is not an error */
+			exit(0);
+		}
+
+		thread_should_exit = false;
+		attitude_estimator_so3_comp_task = task_spawn("attitude_estimator_so3_comp",
+					      SCHED_DEFAULT,
+					      SCHED_PRIORITY_MAX - 5,
+					      12400,
+					      attitude_estimator_so3_comp_thread_main,
+					      (const char **)argv);
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		thread_should_exit = true;
+
+		while(thread_running){
+			usleep(200000);
+			printf(".");
+		}
+		printf("terminated.");
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (thread_running) {
+			printf("\tattitude_estimator_so3_comp app is running\n");
+
+		} else {
+			printf("\tattitude_estimator_so3_comp app not started\n");
+		}
+
+		exit(0);
+	}
+
+	usage("unrecognized command");
+	exit(1);
+}
+
+//---------------------------------------------------------------------------------------------------
+// Fast inverse square-root
+// See: http://en.wikipedia.org/wiki/Fast_inverse_square_root
+float invSqrt(float number) {
+    volatile long i;
+    volatile float x, y;
+    volatile const float f = 1.5F;
+
+    x = number * 0.5F;
+    y = number;
+    i = * (( long * ) &y);
+    i = 0x5f375a86 - ( i >> 1 );
+    y = * (( float * ) &i);
+    y = y * ( f - ( x * y * y ) );
+    return y;
+}
+
+//! Using accelerometer, sense the gravity vector.
+//! Using magnetometer, sense yaw.
+void NonlinearSO3AHRSinit(float ax, float ay, float az, float mx, float my, float mz)
+{
+    float initialRoll, initialPitch;
+    float cosRoll, sinRoll, cosPitch, sinPitch;
+    float magX, magY;
+    float initialHdg, cosHeading, sinHeading;
+
+    initialRoll = atan2(-ay, -az);
+    initialPitch = atan2(ax, -az);
+
+    cosRoll = cosf(initialRoll);
+    sinRoll = sinf(initialRoll);
+    cosPitch = cosf(initialPitch);
+    sinPitch = sinf(initialPitch);
+
+    magX = mx * cosPitch + my * sinRoll * sinPitch + mz * cosRoll * sinPitch;
+
+    magY = my * cosRoll - mz * sinRoll;
+
+    initialHdg = atan2f(-magY, magX);
+
+    cosRoll = cosf(initialRoll * 0.5f);
+    sinRoll = sinf(initialRoll * 0.5f);
+
+    cosPitch = cosf(initialPitch * 0.5f);
+    sinPitch = sinf(initialPitch * 0.5f);
+
+    cosHeading = cosf(initialHdg * 0.5f);
+    sinHeading = sinf(initialHdg * 0.5f);
+
+    q0 = cosRoll * cosPitch * cosHeading + sinRoll * sinPitch * sinHeading;
+    q1 = sinRoll * cosPitch * cosHeading - cosRoll * sinPitch * sinHeading;
+    q2 = cosRoll * sinPitch * cosHeading + sinRoll * cosPitch * sinHeading;
+    q3 = cosRoll * cosPitch * sinHeading - sinRoll * sinPitch * cosHeading;
+
+    // auxillary variables to reduce number of repeated operations, for 1st pass
+    q0q0 = q0 * q0;
+    q0q1 = q0 * q1;
+    q0q2 = q0 * q2;
+    q0q3 = q0 * q3;
+    q1q1 = q1 * q1;
+    q1q2 = q1 * q2;
+    q1q3 = q1 * q3;
+    q2q2 = q2 * q2;
+    q2q3 = q2 * q3;
+    q3q3 = q3 * q3;
+}
+
+void NonlinearSO3AHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz, float twoKp, float twoKi, float dt) {
+	float recipNorm;
+	float halfex = 0.0f, halfey = 0.0f, halfez = 0.0f;
+
+	//! Make filter converge to initial solution faster
+	//! This function assumes you are in static position.
+	//! WARNING : in case air reboot, this can cause problem. But this is very
+	//!	      unlikely happen.
+	if(bFilterInit == false)
+	{
+		NonlinearSO3AHRSinit(ax,ay,az,mx,my,mz);
+		bFilterInit = true;
+	}
+        	
+	//! If magnetometer measurement is available, use it.
+	if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
+		float hx, hy, hz, bx, bz;
+		float halfwx, halfwy, halfwz;
+	
+		// Normalise magnetometer measurement
+		// Will sqrt work better? PX4 system is powerful enough?
+    		recipNorm = invSqrt(mx * mx + my * my + mz * mz);
+    		mx *= recipNorm;
+    		my *= recipNorm;
+    		mz *= recipNorm;
+    
+    		// Reference direction of Earth's magnetic field
+    		hx = 2.0f * (mx * (0.5f - q2q2 - q3q3) + my * (q1q2 - q0q3) + mz * (q1q3 + q0q2));
+    		hy = 2.0f * (mx * (q1q2 + q0q3) + my * (0.5f - q1q1 - q3q3) + mz * (q2q3 - q0q1));
+		hz = 2 * mx * (q1q3 - q0q2) + 2 * my * (q2q3 + q0q1) + 2 * mz * (0.5 - q1q1 - q2q2);
+    		bx = sqrt(hx * hx + hy * hy);
+    		bz = hz;
+    
+    		// Estimated direction of magnetic field
+    		halfwx = bx * (0.5f - q2q2 - q3q3) + bz * (q1q3 - q0q2);
+    		halfwy = bx * (q1q2 - q0q3) + bz * (q0q1 + q2q3);
+    		halfwz = bx * (q0q2 + q1q3) + bz * (0.5f - q1q1 - q2q2);
+    
+    		// Error is sum of cross product between estimated direction and measured direction of field vectors
+    		halfex += (my * halfwz - mz * halfwy);
+    		halfey += (mz * halfwx - mx * halfwz);
+    		halfez += (mx * halfwy - my * halfwx);
+	}
+
+	// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
+	if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
+		float halfvx, halfvy, halfvz;
+	
+		// Normalise accelerometer measurement
+		recipNorm = invSqrt(ax * ax + ay * ay + az * az);
+		ax *= recipNorm;
+		ay *= recipNorm;
+		az *= recipNorm;
+
+		// Estimated direction of gravity and magnetic field
+		halfvx = q1q3 - q0q2;
+		halfvy = q0q1 + q2q3;
+		halfvz = q0q0 - 0.5f + q3q3;
+	
+		// Error is sum of cross product between estimated direction and measured direction of field vectors
+		halfex += ay * halfvz - az * halfvy;
+		halfey += az * halfvx - ax * halfvz;
+		halfez += ax * halfvy - ay * halfvx;
+	}
+
+	// Apply feedback only when valid data has been gathered from the accelerometer or magnetometer
+	if(halfex != 0.0f && halfey != 0.0f && halfez != 0.0f) {
+		// Compute and apply integral feedback if enabled
+		if(twoKi > 0.0f) {
+			gyro_bias[0] += twoKi * halfex * dt;	// integral error scaled by Ki
+			gyro_bias[1] += twoKi * halfey * dt;
+			gyro_bias[2] += twoKi * halfez * dt;
+			gx += gyro_bias[0];	// apply integral feedback
+			gy += gyro_bias[1];
+			gz += gyro_bias[2];
+		}
+		else {
+			gyro_bias[0] = 0.0f;	// prevent integral windup
+			gyro_bias[1] = 0.0f;
+			gyro_bias[2] = 0.0f;
+		}
+
+		// Apply proportional feedback
+		gx += twoKp * halfex;
+		gy += twoKp * halfey;
+		gz += twoKp * halfez;
+	}
+	
+	//! Integrate rate of change of quaternion
+#if 0
+	gx *= (0.5f * dt);		// pre-multiply common factors
+	gy *= (0.5f * dt);
+	gz *= (0.5f * dt);
+#endif 
+
+	// Time derivative of quaternion. q_dot = 0.5*q\otimes omega.
+	//! q_k = q_{k-1} + dt*\dot{q}
+	//! \dot{q} = 0.5*q \otimes P(\omega)
+	dq0 = 0.5f*(-q1 * gx - q2 * gy - q3 * gz);
+	dq1 = 0.5f*(q0 * gx + q2 * gz - q3 * gy);
+	dq2 = 0.5f*(q0 * gy - q1 * gz + q3 * gx);
+	dq3 = 0.5f*(q0 * gz + q1 * gy - q2 * gx); 
+
+	q0 += dt*dq0;
+	q1 += dt*dq1;
+	q2 += dt*dq2;
+	q3 += dt*dq3;
+	
+	// Normalise quaternion
+	recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
+	q0 *= recipNorm;
+	q1 *= recipNorm;
+	q2 *= recipNorm;
+	q3 *= recipNorm;
+
+	// Auxiliary variables to avoid repeated arithmetic
+        q0q0 = q0 * q0;
+       	q0q1 = q0 * q1;
+       	q0q2 = q0 * q2;
+       	q0q3 = q0 * q3;
+       	q1q1 = q1 * q1;
+       	q1q2 = q1 * q2;
+   	q1q3 = q1 * q3;
+       	q2q2 = q2 * q2;
+       	q2q3 = q2 * q3;
+       	q3q3 = q3 * q3;   
+}
+
+void send_uart_byte(char c)
+{
+	write(uart,&c,1);
+}
+
+void send_uart_bytes(uint8_t *data, int length)
+{
+	write(uart,data,(size_t)(sizeof(uint8_t)*length));
+}
+
+void send_uart_float(float f) {
+  uint8_t * b = (uint8_t *) &f;
+
+  //! Assume float is 4-bytes
+  for(int i=0; i<4; i++) {
+    
+    uint8_t b1 = (b[i] >> 4) & 0x0f;
+    uint8_t b2 = (b[i] & 0x0f);
+    
+    uint8_t c1 = (b1 < 10) ? ('0' + b1) : 'A' + b1 - 10;
+    uint8_t c2 = (b2 < 10) ? ('0' + b2) : 'A' + b2 - 10;
+    
+    send_uart_bytes(&c1,1);
+    send_uart_bytes(&c2,1);
+  }
+}
+
+void send_uart_float_arr(float *arr, int length)
+{
+	for(int i=0;i<length;++i)
+	{
+		send_uart_float(arr[i]);
+		send_uart_byte(',');
+	}
+}
+
+int open_uart(int baud, const char *uart_name, struct termios *uart_config_original, bool *is_usb)
+{
+	int speed;
+	
+	switch (baud) {
+        case 0:      speed = B0;      break;
+        case 50:     speed = B50;     break;
+        case 75:     speed = B75;     break;
+        case 110:    speed = B110;    break;
+        case 134:    speed = B134;    break;
+        case 150:    speed = B150;    break;
+        case 200:    speed = B200;    break;
+        case 300:    speed = B300;    break;
+        case 600:    speed = B600;    break;
+        case 1200:   speed = B1200;   break;
+        case 1800:   speed = B1800;   break;
+        case 2400:   speed = B2400;   break;
+        case 4800:   speed = B4800;   break;
+        case 9600:   speed = B9600;   break;
+        case 19200:  speed = B19200;  break;
+        case 38400:  speed = B38400;  break;
+        case 57600:  speed = B57600;  break;
+        case 115200: speed = B115200; break;
+        case 230400: speed = B230400; break;
+        case 460800: speed = B460800; break;
+        case 921600: speed = B921600; break;
+        default:
+                printf("ERROR: Unsupported baudrate: %d\n\tsupported examples:\n\n\t9600\n19200\n38400\n57600\n115200\n230400\n460800\n921600\n\n", baud);
+                return -EINVAL;
+        }
+
+	printf("[so3_comp_filt] UART is %s, baudrate is %d\n", uart_name, baud);
+        uart = open(uart_name, O_RDWR | O_NOCTTY);
+
+	/* Try to set baud rate */
+        struct termios uart_config;
+        int termios_state;
+        *is_usb = false;
+
+	/* make some wild guesses including that USB serial is indicated by either /dev/ttyACM0 or /dev/console */
+        if (strcmp(uart_name, "/dev/ttyACM0") != OK && strcmp(uart_name, "/dev/console") != OK) {
+                /* Back up the original uart configuration to restore it after exit */
+                if ((termios_state = tcgetattr(uart, uart_config_original)) < 0) {
+                        printf("ERROR getting baudrate / termios config for %s: %d\n", uart_name, termios_state);
+                        close(uart);
+                        return -1;
+                }
+
+                /* Fill the struct for the new configuration */
+                tcgetattr(uart, &uart_config);
+
+                /* Clear ONLCR flag (which appends a CR for every LF) */
+                uart_config.c_oflag &= ~ONLCR;
+
+                /* Set baud rate */
+                if (cfsetispeed(&uart_config, speed) < 0 || cfsetospeed(&uart_config, speed) < 0) {
+                        printf("ERROR setting baudrate / termios config for %s: %d (cfsetispeed, cfsetospeed)\n", uart_name, termios_state);
+                        close(uart);
+                        return -1;
+                }
+
+
+                if ((termios_state = tcsetattr(uart, TCSANOW, &uart_config)) < 0) {
+                        printf("ERROR setting baudrate / termios config for %s (tcsetattr)\n", uart_name);
+                        close(uart);
+                        return -1;
+                }
+
+        } else {
+                *is_usb = true;
+        }
+
+        return uart;
+}
+
+/*
+ * [Rot_matrix,x_aposteriori,P_aposteriori] = attitudeKalmanfilter(dt,z_k,x_aposteriori_k,P_aposteriori_k,knownConst)
+ */
+
+/*
+ * EKF Attitude Estimator main function.
+ *
+ * Estimates the attitude recursively once started.
+ *
+ * @param argc number of commandline arguments (plus command name)
+ * @param argv strings containing the arguments
+ */
+int attitude_estimator_so3_comp_thread_main(int argc, char *argv[])
+{
+
+const unsigned int loop_interval_alarm = 6500;	// loop interval in microseconds
+
+	//! Serial debug related
+	int ch;
+	struct termios uart_config_original;
+	bool usb_uart;
+	bool debug_mode = false;
+	char *device_name = "/dev/ttyS2";
+	baudrate = 115200;
+
+	//! Time constant
+	float dt = 0.005f;
+	
+	/* output euler angles */
+	float euler[3] = {0.0f, 0.0f, 0.0f};
+
+	float Rot_matrix[9] = {1.f,  0,  0,
+			      0,  1.f,  0,
+			      0,  0,  1.f
+			     };		/**< init: identity matrix */
+
+	float acc[3] = {0.0f, 0.0f, 0.0f};
+	float gyro[3] = {0.0f, 0.0f, 0.0f};
+	float mag[3] = {0.0f, 0.0f, 0.0f};
+
+	/* work around some stupidity in task_create's argv handling */
+	argc -= 2;
+	argv += 2;
+
+	//! -d <device_name>, default : /dev/ttyS2
+	//! -b <baud_rate>,   default : 115200
+	while ((ch = getopt(argc,argv,"d:b:")) != EOF){
+		switch(ch){
+			case 'b':
+				baudrate = strtoul(optarg, NULL, 10);
+				if(baudrate == 0)
+					printf("invalid baud rate '%s'",optarg);
+				break;
+			case 'd':
+				device_name = optarg;
+				debug_mode = true;
+				break;
+			default:
+				usage("invalid argument");
+		}
+	}
+
+	if(debug_mode){
+		printf("Opening debugging port for 3D visualization\n");
+		uart = open_uart(baudrate, device_name, &uart_config_original, &usb_uart);
+		if (uart < 0)
+                	printf("could not open %s", device_name);
+		else
+			printf("Open port success\n");
+	}
+
+	// print text
+	printf("Nonlinear SO3 Attitude Estimator initialized..\n\n");
+	fflush(stdout);
+
+	int overloadcounter = 19;
+
+	/* store start time to guard against too slow update rates */
+	uint64_t last_run = hrt_absolute_time();
+
+	struct sensor_combined_s raw;
+	memset(&raw, 0, sizeof(raw));
+
+	//! Initialize attitude vehicle uORB message.
+	struct vehicle_attitude_s att;
+	memset(&att, 0, sizeof(att));
+
+	struct vehicle_status_s state;
+	memset(&state, 0, sizeof(state));
+
+	uint64_t last_data = 0;
+	uint64_t last_measurement = 0;
+
+	/* subscribe to raw data */
+	int sub_raw = orb_subscribe(ORB_ID(sensor_combined));
+	/* rate-limit raw data updates to 200Hz */
+	orb_set_interval(sub_raw, 4);
+
+	/* subscribe to param changes */
+	int sub_params = orb_subscribe(ORB_ID(parameter_update));
+
+	/* subscribe to system state*/
+	int sub_state = orb_subscribe(ORB_ID(vehicle_status));
+
+	/* advertise attitude */
+	orb_advert_t pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
+
+	int loopcounter = 0;
+	int printcounter = 0;
+
+	thread_running = true;
+
+	/* advertise debug value */
+	// struct debug_key_value_s dbg = { .key = "", .value = 0.0f };
+	// orb_advert_t pub_dbg = -1;
+
+	float sensor_update_hz[3] = {0.0f, 0.0f, 0.0f};
+	// XXX write this out to perf regs
+
+	/* keep track of sensor updates */
+	uint32_t sensor_last_count[3] = {0, 0, 0};
+	uint64_t sensor_last_timestamp[3] = {0, 0, 0};
+
+	struct attitude_estimator_so3_comp_params so3_comp_params;
+	struct attitude_estimator_so3_comp_param_handles so3_comp_param_handles;
+
+	/* initialize parameter handles */
+	parameters_init(&so3_comp_param_handles);
+
+	uint64_t start_time = hrt_absolute_time();
+	bool initialized = false;
+
+	float gyro_offsets[3] = { 0.0f, 0.0f, 0.0f };
+	unsigned offset_count = 0;
+
+	/* register the perf counter */
+	perf_counter_t so3_comp_loop_perf = perf_alloc(PC_ELAPSED, "attitude_estimator_so3_comp");
+
+	/* Main loop*/
+	while (!thread_should_exit) {
+
+		struct pollfd fds[2];
+		fds[0].fd = sub_raw;
+		fds[0].events = POLLIN;
+		fds[1].fd = sub_params;
+		fds[1].events = POLLIN;
+		int ret = poll(fds, 2, 1000);
+
+		if (ret < 0) {
+			/* XXX this is seriously bad - should be an emergency */
+		} else if (ret == 0) {
+			/* check if we're in HIL - not getting sensor data is fine then */
+			orb_copy(ORB_ID(vehicle_status), sub_state, &state);
+
+			if (!state.flag_hil_enabled) {
+				fprintf(stderr,
+					"[att so3_comp] WARNING: Not getting sensors - sensor app running?\n");
+			}
+
+		} else {
+
+			/* only update parameters if they changed */
+			if (fds[1].revents & POLLIN) {
+				/* read from param to clear updated flag */
+				struct parameter_update_s update;
+				orb_copy(ORB_ID(parameter_update), sub_params, &update);
+
+				/* update parameters */
+				parameters_update(&so3_comp_param_handles, &so3_comp_params);
+			}
+
+			/* only run filter if sensor values changed */
+			if (fds[0].revents & POLLIN) {
+
+				/* get latest measurements */
+				orb_copy(ORB_ID(sensor_combined), sub_raw, &raw);
+
+				if (!initialized) {
+
+					gyro_offsets[0] += raw.gyro_rad_s[0];
+					gyro_offsets[1] += raw.gyro_rad_s[1];
+					gyro_offsets[2] += raw.gyro_rad_s[2];
+					offset_count++;
+
+					if (hrt_absolute_time() - start_time > 3000000LL) {
+						initialized = true;
+						gyro_offsets[0] /= offset_count;
+						gyro_offsets[1] /= offset_count;
+						gyro_offsets[2] /= offset_count;
+					}
+
+				} else {
+
+					perf_begin(so3_comp_loop_perf);
+
+					/* Calculate data time difference in seconds */
+					dt = (raw.timestamp - last_measurement) / 1000000.0f;
+					last_measurement = raw.timestamp;
+					uint8_t update_vect[3] = {0, 0, 0};
+
+					/* Fill in gyro measurements */
+					if (sensor_last_count[0] != raw.gyro_counter) {
+						update_vect[0] = 1;
+						sensor_last_count[0] = raw.gyro_counter;
+						sensor_update_hz[0] = 1e6f / (raw.timestamp - sensor_last_timestamp[0]);
+						sensor_last_timestamp[0] = raw.timestamp;
+					}
+
+					gyro[0] =  raw.gyro_rad_s[0] - gyro_offsets[0];
+					gyro[1] =  raw.gyro_rad_s[1] - gyro_offsets[1];
+					gyro[2] =  raw.gyro_rad_s[2] - gyro_offsets[2];
+
+					/* update accelerometer measurements */
+					if (sensor_last_count[1] != raw.accelerometer_counter) {
+						update_vect[1] = 1;
+						sensor_last_count[1] = raw.accelerometer_counter;
+						sensor_update_hz[1] = 1e6f / (raw.timestamp - sensor_last_timestamp[1]);
+						sensor_last_timestamp[1] = raw.timestamp;
+					}
+
+					acc[0] = raw.accelerometer_m_s2[0];
+					acc[1] = raw.accelerometer_m_s2[1];
+					acc[2] = raw.accelerometer_m_s2[2];
+
+					/* update magnetometer measurements */
+					if (sensor_last_count[2] != raw.magnetometer_counter) {
+						update_vect[2] = 1;
+						sensor_last_count[2] = raw.magnetometer_counter;
+						sensor_update_hz[2] = 1e6f / (raw.timestamp - sensor_last_timestamp[2]);
+						sensor_last_timestamp[2] = raw.timestamp;
+					}
+
+					mag[0] = raw.magnetometer_ga[0];
+					mag[1] = raw.magnetometer_ga[1];
+					mag[2] = raw.magnetometer_ga[2];
+
+					uint64_t now = hrt_absolute_time();
+					unsigned int time_elapsed = now - last_run;
+					last_run = now;
+
+					if (time_elapsed > loop_interval_alarm) {
+						//TODO: add warning, cpu overload here
+						// if (overloadcounter == 20) {
+						// 	printf("CPU OVERLOAD DETECTED IN ATTITUDE ESTIMATOR EKF (%lu > %lu)\n", time_elapsed, loop_interval_alarm);
+						// 	overloadcounter = 0;
+						// }
+
+						overloadcounter++;
+					}
+
+					static bool const_initialized = false;
+
+					/* initialize with good values once we have a reasonable dt estimate */
+					if (!const_initialized && dt < 0.05f && dt > 0.005f) {
+						dt = 0.005f;
+						parameters_update(&so3_comp_param_handles, &so3_comp_params);
+						const_initialized = true;
+					}
+
+					/* do not execute the filter if not initialized */
+					if (!const_initialized) {
+						continue;
+					}
+
+					uint64_t timing_start = hrt_absolute_time();
+
+					// NOTE : Accelerometer is reversed.
+					// Because proper mount of PX4 will give you a reversed accelerometer readings.
+					NonlinearSO3AHRSupdate(gyro[0],gyro[1],gyro[2],-acc[0],-acc[1],-acc[2],mag[0],mag[1],mag[2],so3_comp_params.Kp,so3_comp_params.Ki, dt);
+
+					// Convert q->R.
+					Rot_matrix[0] = q0q0 + q1q1 - q2q2 - q3q3;// 11
+        				Rot_matrix[1] = 2.0 * (q1*q2 + q0*q3);	// 12
+        				Rot_matrix[2] = 2.0 * (q1*q3 - q0*q2);	// 13
+        				Rot_matrix[3] = 2.0 * (q1*q2 - q0*q3);	// 21
+        				Rot_matrix[4] = q0q0 - q1q1 + q2q2 - q3q3;// 22
+        				Rot_matrix[5] = 2.0 * (q2*q3 + q0*q1);	// 23
+        				Rot_matrix[6] = 2.0 * (q1*q3 + q0*q2);	// 31
+        				Rot_matrix[7] = 2.0 * (q2*q3 - q0*q1);	// 32
+        				Rot_matrix[8] = q0q0 - q1q1 - q2q2 + q3q3;// 33
+
+					//1-2-3 Representation.
+					//Equation (290) 
+					//Representing Attitude: Euler Angles, Unit Quaternions, and Rotation Vectors, James Diebel.
+					// Existing PX4 EKF code was generated by MATLAB which uses coloum major order matrix.
+					euler[0] = atan2f(Rot_matrix[5], Rot_matrix[8]);	//! Roll
+					euler[1] = -asinf(Rot_matrix[2]);	//! Pitch
+					euler[2] = atan2f(Rot_matrix[1],Rot_matrix[0]);		//! Yaw
+					
+					/* swap values for next iteration, check for fatal inputs */
+					if (isfinite(euler[0]) && isfinite(euler[1]) && isfinite(euler[2])) {
+						/* Do something */
+					} else {
+						/* due to inputs or numerical failure the output is invalid, skip it */
+						continue;
+					}
+
+					if (last_data > 0 && raw.timestamp - last_data > 12000) printf("[attitude estimator so3_comp] sensor data missed! (%llu)\n", raw.timestamp - last_data);
+
+					last_data = raw.timestamp;
+
+					/* send out */
+					att.timestamp = raw.timestamp;
+
+					// XXX Apply the same transformation to the rotation matrix
+					att.roll = euler[0] - so3_comp_params.roll_off;
+					att.pitch = euler[1] - so3_comp_params.pitch_off;
+					att.yaw = euler[2] - so3_comp_params.yaw_off;
+
+					//! Euler angle rate. But it needs to be investigated again.
+					/*
+					att.rollspeed = 2.0f*(-q1*dq0 + q0*dq1 - q3*dq2 + q2*dq3);
+					att.pitchspeed = 2.0f*(-q2*dq0 + q3*dq1 + q0*dq2 - q1*dq3);
+					att.yawspeed = 2.0f*(-q3*dq0 -q2*dq1 + q1*dq2 + q0*dq3);
+					*/
+					att.rollspeed = gyro[0];
+					att.pitchspeed = gyro[1];
+					att.yawspeed = gyro[2];
+
+					att.rollacc = 0;
+					att.pitchacc = 0;
+					att.yawacc = 0;
+
+					//! Quaternion
+					att.q[0] = q0;
+					att.q[1] = q1;
+					att.q[2] = q2;
+					att.q[3] = q3;
+					att.q_valid = true;
+
+					/* TODO: Bias estimation required */
+					memcpy(&att.rate_offsets, &(gyro_bias), sizeof(att.rate_offsets));
+
+					/* copy rotation matrix */
+					memcpy(&att.R, Rot_matrix, sizeof(Rot_matrix));
+					att.R_valid = true;
+
+					if (isfinite(att.roll) && isfinite(att.pitch) && isfinite(att.yaw)) {
+						// Broadcast
+						orb_publish(ORB_ID(vehicle_attitude), pub_att, &att);
+
+					} else {
+						warnx("NaN in roll/pitch/yaw estimate!");
+					}
+
+					perf_end(so3_comp_loop_perf);
+
+					//! This will print out debug packet to visualization software
+					if(debug_mode)
+					{
+						float quat[4];
+						quat[0] = q0;
+						quat[1] = q1;
+						quat[2] = q2;
+						quat[3] = q3;
+						send_uart_float_arr(quat,4);
+						send_uart_byte('\n');
+					}
+				}
+			}
+		}
+
+		loopcounter++;
+	}// while
+
+	thread_running = false;
+
+	/* Reset the UART flags to original state */
+        if (!usb_uart)
+                tcsetattr(uart, TCSANOW, &uart_config_original);
+
+	return 0;
+}
diff --git a/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_params.c b/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_params.c
new file mode 100755
index 000000000..f962515df
--- /dev/null
+++ b/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_params.c
@@ -0,0 +1,63 @@
+/*
+ * Author: Hyon Lim <limhyon@gmail.com, hyonlim@snu.ac.kr>
+ *
+ * @file attitude_estimator_so3_comp_params.c
+ *
+ * Implementation of nonlinear complementary filters on the SO(3).
+ * This code performs attitude estimation by using accelerometer, gyroscopes and magnetometer.
+ * Result is provided as quaternion, 1-2-3 Euler angle and rotation matrix.
+ * 
+ * Theory of nonlinear complementary filters on the SO(3) is based on [1].
+ * Quaternion realization of [1] is based on [2].
+ * Optmized quaternion update code is based on Sebastian Madgwick's implementation.
+ * 
+ * References
+ *  [1] Mahony, R.; Hamel, T.; Pflimlin, Jean-Michel, "Nonlinear Complementary Filters on the Special Orthogonal Group," Automatic Control, IEEE Transactions on , vol.53, no.5, pp.1203,1218, June 2008
+ *  [2] Euston, M.; Coote, P.; Mahony, R.; Jonghyuk Kim; Hamel, T., "A complementary filter for attitude estimation of a fixed-wing UAV," Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on , vol., no., pp.340,345, 22-26 Sept. 2008
+ */
+
+#include "attitude_estimator_so3_comp_params.h"
+
+/* This is filter gain for nonlinear SO3 complementary filter */
+/* NOTE : How to tune the gain? First of all, stick with this default gain. And let the quad in stable place.
+   Log the steady state reponse of filter. If it is too slow, increase SO3_COMP_KP.
+   If you are flying from ground to high altitude in short amount of time, please increase SO3_COMP_KI which
+   will compensate gyro bias which depends on temperature and vibration of your vehicle */
+PARAM_DEFINE_FLOAT(SO3_COMP_KP, 1.0f); //! This parameter will give you about 15 seconds convergence time.
+                                       //! You can set this gain higher if you want more fast response.
+                                       //! But note that higher gain will give you also higher overshoot.
+PARAM_DEFINE_FLOAT(SO3_COMP_KI, 0.05f); //! This gain will incorporate slow time-varying bias (e.g., temperature change)
+					//! This gain is depend on your vehicle status.
+
+/* offsets in roll, pitch and yaw of sensor plane and body */
+PARAM_DEFINE_FLOAT(ATT_ROLL_OFFS, 0.0f);
+PARAM_DEFINE_FLOAT(ATT_PITCH_OFFS, 0.0f);
+PARAM_DEFINE_FLOAT(ATT_YAW_OFFS, 0.0f);
+
+int parameters_init(struct attitude_estimator_so3_comp_param_handles *h)
+{
+	/* Filter gain parameters */
+	h->Kp = 	param_find("SO3_COMP_KP");
+	h->Ki = 	param_find("SO3_COMP_KI");
+
+	/* Attitude offset (WARNING: Do not change if you do not know what exactly this variable wil lchange) */
+	h->roll_off  =	param_find("ATT_ROLL_OFFS");
+	h->pitch_off =	param_find("ATT_PITCH_OFFS");
+	h->yaw_off   =	param_find("ATT_YAW_OFFS");
+
+	return OK;
+}
+
+int parameters_update(const struct attitude_estimator_so3_comp_param_handles *h, struct attitude_estimator_so3_comp_params *p)
+{
+	/* Update filter gain */
+	param_get(h->Kp, &(p->Kp));
+	param_get(h->Ki, &(p->Ki));
+
+	/* Update attitude offset */
+	param_get(h->roll_off, &(p->roll_off));
+	param_get(h->pitch_off, &(p->pitch_off));
+	param_get(h->yaw_off, &(p->yaw_off));
+
+	return OK;
+}
diff --git a/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_params.h b/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_params.h
new file mode 100755
index 000000000..f00695630
--- /dev/null
+++ b/src/modules/attitude_estimator_so3_comp/attitude_estimator_so3_comp_params.h
@@ -0,0 +1,44 @@
+/*
+ * Author: Hyon Lim <limhyon@gmail.com, hyonlim@snu.ac.kr>
+ *
+ * @file attitude_estimator_so3_comp_params.h
+ *
+ * Implementation of nonlinear complementary filters on the SO(3).
+ * This code performs attitude estimation by using accelerometer, gyroscopes and magnetometer.
+ * Result is provided as quaternion, 1-2-3 Euler angle and rotation matrix.
+ * 
+ * Theory of nonlinear complementary filters on the SO(3) is based on [1].
+ * Quaternion realization of [1] is based on [2].
+ * Optmized quaternion update code is based on Sebastian Madgwick's implementation.
+ * 
+ * References
+ *  [1] Mahony, R.; Hamel, T.; Pflimlin, Jean-Michel, "Nonlinear Complementary Filters on the Special Orthogonal Group," Automatic Control, IEEE Transactions on , vol.53, no.5, pp.1203,1218, June 2008
+ *  [2] Euston, M.; Coote, P.; Mahony, R.; Jonghyuk Kim; Hamel, T., "A complementary filter for attitude estimation of a fixed-wing UAV," Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on , vol., no., pp.340,345, 22-26 Sept. 2008
+ */
+
+#include <systemlib/param/param.h>
+
+struct attitude_estimator_so3_comp_params {
+	float Kp;
+	float Ki;
+	float roll_off;
+	float pitch_off;
+	float yaw_off;
+};
+
+struct attitude_estimator_so3_comp_param_handles {
+	param_t Kp, Ki;
+	param_t roll_off, pitch_off, yaw_off;
+};
+
+/**
+ * Initialize all parameter handles and values
+ *
+ */
+int parameters_init(struct attitude_estimator_so3_comp_param_handles *h);
+
+/**
+ * Update all parameters
+ *
+ */
+int parameters_update(const struct attitude_estimator_so3_comp_param_handles *h, struct attitude_estimator_so3_comp_params *p);
diff --git a/src/modules/attitude_estimator_so3_comp/module.mk b/src/modules/attitude_estimator_so3_comp/module.mk
new file mode 100644
index 000000000..92f43d920
--- /dev/null
+++ b/src/modules/attitude_estimator_so3_comp/module.mk
@@ -0,0 +1,8 @@
+#
+# Attitude estimator (Nonlinear SO3 complementary Filter)
+#
+
+MODULE_COMMAND	 = attitude_estimator_so3_comp
+
+SRCS		 = attitude_estimator_so3_comp_main.cpp \
+		   attitude_estimator_so3_comp_params.c
diff --git a/src/modules/fixedwing_backside/fixedwing_backside_main.cpp b/src/modules/fixedwing_backside/fixedwing_backside_main.cpp
index e21990c92..c3d57a85a 100644
--- a/src/modules/fixedwing_backside/fixedwing_backside_main.cpp
+++ b/src/modules/fixedwing_backside/fixedwing_backside_main.cpp
@@ -47,6 +47,7 @@
 #include <systemlib/systemlib.h>
 #include <controllib/fixedwing.hpp>
 #include <systemlib/param/param.h>
+#include <systemlib/err.h>
 #include <drivers/drv_hrt.h>
 #include <math.h>
 
@@ -80,7 +81,7 @@ usage(const char *reason)
 	if (reason)
 		fprintf(stderr, "%s\n", reason);
 
-	fprintf(stderr, "usage: control_demo {start|stop|status} [-p <additional params>]\n\n");
+	fprintf(stderr, "usage: fixedwing_backside {start|stop|status} [-p <additional params>]\n\n");
 	exit(1);
 }
 
@@ -101,13 +102,13 @@ int fixedwing_backside_main(int argc, char *argv[])
 	if (!strcmp(argv[1], "start")) {
 
 		if (thread_running) {
-			printf("control_demo already running\n");
+			warnx("already running");
 			/* this is not an error */
 			exit(0);
 		}
 
 		thread_should_exit = false;
-		deamon_task = task_spawn("control_demo",
+		deamon_task = task_spawn("fixedwing_backside",
 					 SCHED_DEFAULT,
 					 SCHED_PRIORITY_MAX - 10,
 					 5120,
@@ -128,10 +129,10 @@ int fixedwing_backside_main(int argc, char *argv[])
 
 	if (!strcmp(argv[1], "status")) {
 		if (thread_running) {
-			printf("\tcontrol_demo app is running\n");
+			warnx("is running");
 
 		} else {
-			printf("\tcontrol_demo app not started\n");
+			warnx("not started");
 		}
 
 		exit(0);
@@ -144,7 +145,7 @@ int fixedwing_backside_main(int argc, char *argv[])
 int control_demo_thread_main(int argc, char *argv[])
 {
 
-	printf("[control_Demo] starting\n");
+	warnx("starting");
 
 	using namespace control;
 
@@ -156,7 +157,7 @@ int control_demo_thread_main(int argc, char *argv[])
 		autopilot.update();
 	}
 
-	printf("[control_demo] exiting.\n");
+	warnx("exiting.");
 
 	thread_running = false;
 
@@ -165,6 +166,6 @@ int control_demo_thread_main(int argc, char *argv[])
 
 void test()
 {
-	printf("beginning control lib test\n");
+	warnx("beginning control lib test");
 	control::basicBlocksTest();
 }
diff --git a/src/modules/gpio_led/gpio_led.c b/src/modules/gpio_led/gpio_led.c
new file mode 100644
index 000000000..43cbe74c7
--- /dev/null
+++ b/src/modules/gpio_led/gpio_led.c
@@ -0,0 +1,217 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <anton.babushkin@me.com>
+ *
+ * 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 gpio_led.c
+ *
+ * Status LED via GPIO driver.
+ *
+ * @author Anton Babushkin <anton.babushkin@me.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <nuttx/wqueue.h>
+#include <nuttx/clock.h>
+#include <systemlib/systemlib.h>
+#include <systemlib/err.h>
+#include <uORB/uORB.h>
+#include <uORB/topics/vehicle_status.h>
+#include <poll.h>
+#include <drivers/drv_gpio.h>
+
+struct gpio_led_s {
+	struct work_s work;
+	int gpio_fd;
+	int pin;
+	struct vehicle_status_s status;
+	int vehicle_status_sub;
+	bool led_state;
+	int counter;
+};
+
+static struct gpio_led_s gpio_led_data;
+static bool gpio_led_started = false;
+
+__EXPORT int gpio_led_main(int argc, char *argv[]);
+
+void gpio_led_start(FAR void *arg);
+
+void gpio_led_cycle(FAR void *arg);
+
+int gpio_led_main(int argc, char *argv[])
+{
+	int pin = GPIO_EXT_1;
+
+	if (argc < 2) {
+		errx(1, "no argument provided. Try 'start' or 'stop' [-p 1/2]");
+
+	} else {
+
+		/* START COMMAND HANDLING */
+		if (!strcmp(argv[1], "start")) {
+
+			if (argc > 2) {
+				if (!strcmp(argv[1], "-p")) {
+					if (!strcmp(argv[2], "1")) {
+						pin = GPIO_EXT_1;
+
+					} else if (!strcmp(argv[2], "2")) {
+						pin = GPIO_EXT_2;
+
+					} else {
+						warnx("[gpio_led] Unsupported pin: %s\n", argv[2]);
+						exit(1);
+					}
+				}
+			}
+
+			memset(&gpio_led_data, 0, sizeof(gpio_led_data));
+			gpio_led_data.pin = pin;
+			int ret = work_queue(LPWORK, &gpio_led_data.work, gpio_led_start, &gpio_led_data, 0);
+
+			if (ret != 0) {
+				warnx("[gpio_led] Failed to queue work: %d\n", ret);
+				exit(1);
+
+			} else {
+				gpio_led_started = true;
+			}
+
+			exit(0);
+
+			/* STOP COMMAND HANDLING */
+
+		} else if (!strcmp(argv[1], "stop")) {
+			gpio_led_started = false;
+
+			/* INVALID COMMAND */
+
+		} else {
+			errx(1, "unrecognized command '%s', only supporting 'start' or 'stop'", argv[1]);
+		}
+	}
+}
+
+void gpio_led_start(FAR void *arg)
+{
+	FAR struct gpio_led_s *priv = (FAR struct gpio_led_s *)arg;
+
+	/* open GPIO device */
+	priv->gpio_fd = open(GPIO_DEVICE_PATH, 0);
+
+	if (priv->gpio_fd < 0) {
+		warnx("[gpio_led] GPIO: open fail\n");
+		return;
+	}
+
+	/* configure GPIO pin */
+	ioctl(priv->gpio_fd, GPIO_SET_OUTPUT, priv->pin);
+
+	/* subscribe to vehicle status topic */
+	memset(&priv->status, 0, sizeof(priv->status));
+	priv->vehicle_status_sub = orb_subscribe(ORB_ID(vehicle_status));
+
+	/* add worker to queue */
+	int ret = work_queue(LPWORK, &priv->work, gpio_led_cycle, priv, 0);
+
+	if (ret != 0) {
+		warnx("[gpio_led] Failed to queue work: %d\n", ret);
+		return;
+	}
+
+	warnx("[gpio_led] Started, using pin GPIO_EXT%i\n", priv->pin);
+}
+
+void gpio_led_cycle(FAR void *arg)
+{
+	FAR struct gpio_led_s *priv = (FAR struct gpio_led_s *)arg;
+
+	/* check for status updates*/
+	bool status_updated;
+	orb_check(priv->vehicle_status_sub, &status_updated);
+
+	if (status_updated)
+		orb_copy(ORB_ID(vehicle_status), priv->vehicle_status_sub, &priv->status);
+
+	/* select pattern for current status */
+	int pattern = 0;
+
+	if (priv->status.flag_system_armed) {
+		if (priv->status.battery_warning == VEHICLE_BATTERY_WARNING_NONE) {
+			pattern = 0x3f;	// ****** solid (armed)
+
+		} else {
+			pattern = 0x2A;	// *_*_*_ fast blink (armed, battery warning)
+		}
+
+	} else {
+		if (priv->status.state_machine == SYSTEM_STATE_PREFLIGHT) {
+			pattern = 0x00;	// ______ off (disarmed, preflight check)
+
+		} else if (priv->status.state_machine == SYSTEM_STATE_STANDBY &&
+			   priv->status.battery_warning == VEHICLE_BATTERY_WARNING_NONE) {
+			pattern = 0x38;	// ***___ slow blink (disarmed, ready)
+
+		} else {
+			pattern = 0x28;	// *_*___ slow double blink (disarmed, not good to arm)
+		}
+	}
+
+	/* blink pattern */
+	bool led_state_new = (pattern & (1 << priv->counter)) != 0;
+
+	if (led_state_new != priv->led_state) {
+		priv->led_state = led_state_new;
+
+		if (led_state_new) {
+			ioctl(priv->gpio_fd, GPIO_SET, priv->pin);
+
+		} else {
+			ioctl(priv->gpio_fd, GPIO_CLEAR, priv->pin);
+		}
+	}
+
+	priv->counter++;
+
+	if (priv->counter > 5)
+		priv->counter = 0;
+
+	/* repeat cycle at 5 Hz*/
+	if (gpio_led_started)
+		work_queue(LPWORK, &priv->work, gpio_led_cycle, priv, USEC2TICK(200000));
+}
diff --git a/src/modules/gpio_led/module.mk b/src/modules/gpio_led/module.mk
new file mode 100644
index 000000000..3b8553489
--- /dev/null
+++ b/src/modules/gpio_led/module.mk
@@ -0,0 +1,39 @@
+############################################################################
+#
+#   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
+# 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.
+#
+############################################################################
+
+#
+# Status LED via GPIO driver
+#
+
+MODULE_COMMAND	= gpio_led
+SRCS			= gpio_led.c
diff --git a/src/modules/mavlink/mavlink_receiver.c b/src/modules/mavlink/mavlink_receiver.c
index a42612f9e..940d030b2 100644
--- a/src/modules/mavlink/mavlink_receiver.c
+++ b/src/modules/mavlink/mavlink_receiver.c
@@ -429,11 +429,11 @@ handle_message(mavlink_message_t *msg)
 			hil_frames += 1 ;
 
 			// output
-			if ((timestamp - old_timestamp) > 10000000) {
-				printf("receiving hil gps at %d hz\n", hil_frames/10);
-				old_timestamp = timestamp;
-				hil_frames = 0;
-			}
+			// if ((timestamp - old_timestamp) > 10000000) {
+			// 	printf("receiving hil gps at %d hz\n", hil_frames/10);
+			// 	old_timestamp = timestamp;
+			// 	hil_frames = 0;
+			// }
 		}
 
 		if (msg->msgid == MAVLINK_MSG_ID_HIL_STATE) {
diff --git a/src/modules/px4iofirmware/mixer.cpp b/src/modules/px4iofirmware/mixer.cpp
index 1234e2eea..a2193b526 100644
--- a/src/modules/px4iofirmware/mixer.cpp
+++ b/src/modules/px4iofirmware/mixer.cpp
@@ -85,6 +85,9 @@ static int	mixer_callback(uintptr_t handle,
 
 static MixerGroup mixer_group(mixer_callback, 0);
 
+/* Set the failsafe values of all mixed channels (based on zero throttle, controls centered) */
+static void mixer_set_failsafe();
+
 void
 mixer_tick(void)
 {
@@ -102,13 +105,16 @@ mixer_tick(void)
 		r_status_flags |= PX4IO_P_STATUS_FLAGS_FMU_OK;
 	}
 
+	/* default to failsafe mixing */
 	source = MIX_FAILSAFE;
 
 	/*
 	 * Decide which set of controls we're using.
 	 */
-	if ((r_status_flags & PX4IO_P_STATUS_FLAGS_RAW_PWM) ||
-		!(r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK)) {
+
+	/* do not mix if mixer is invalid or if RAW_PWM mode is on and FMU is good */
+	if ((r_status_flags & PX4IO_P_STATUS_FLAGS_RAW_PWM) &&
+	        !(r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK)) {
 
 		/* don't actually mix anything - we already have raw PWM values or
 		 not a valid mixer. */
@@ -117,6 +123,7 @@ mixer_tick(void)
 	} else {
 
 		if (!(r_status_flags & PX4IO_P_STATUS_FLAGS_OVERRIDE) &&
+		     (r_status_flags & PX4IO_P_STATUS_FLAGS_FMU_OK) &&
 		     (r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK)) {
 
 			/* mix from FMU controls */
@@ -133,14 +140,28 @@ mixer_tick(void)
 	}
 
 	/*
+	 * Set failsafe status flag depending on mixing source
+	 */
+	if (source == MIX_FAILSAFE) {
+		r_status_flags |= PX4IO_P_STATUS_FLAGS_FAILSAFE;
+	} else {
+		r_status_flags &= ~(PX4IO_P_STATUS_FLAGS_FAILSAFE);
+	}
+
+	/*
 	 * Run the mixers.
 	 */
 	if (source == MIX_FAILSAFE) {
 
 		/* copy failsafe values to the servo outputs */
-		for (unsigned i = 0; i < IO_SERVO_COUNT; i++)
+		for (unsigned i = 0; i < IO_SERVO_COUNT; i++) {
 			r_page_servos[i] = r_page_servo_failsafe[i];
 
+			/* safe actuators for FMU feedback */
+			r_page_actuators[i] = (r_page_servos[i] - 1500) / 600.0f;
+		}
+
+
 	} else if (source != MIX_NONE) {
 
 		float	outputs[IO_SERVO_COUNT];
@@ -156,7 +177,7 @@ mixer_tick(void)
 			r_page_actuators[i] = FLOAT_TO_REG(outputs[i]);
 
 			/* scale to servo output */
-			r_page_servos[i] = (outputs[i] * 500.0f) + 1500;
+			r_page_servos[i] = (outputs[i] * 600.0f) + 1500;
 
 		}
 		for (unsigned i = mixed; i < IO_SERVO_COUNT; i++)
@@ -175,7 +196,7 @@ mixer_tick(void)
 	bool should_arm = (
 	    /* FMU is armed */ (r_setup_arming & PX4IO_P_SETUP_ARMING_FMU_ARMED) &&
 	 	/* IO is armed */  (r_status_flags & PX4IO_P_STATUS_FLAGS_ARMED) &&
-		/* there is valid input */ (r_status_flags & (PX4IO_P_STATUS_FLAGS_RAW_PWM | PX4IO_P_STATUS_FLAGS_MIXER_OK)) &&
+		/* there is valid input via direct PWM or mixer */ (r_status_flags & (PX4IO_P_STATUS_FLAGS_RAW_PWM | PX4IO_P_STATUS_FLAGS_MIXER_OK)) &&
 		/* IO initialised without error */  (r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK) &&
 		/* FMU is available or FMU is not available but override is an option */
 		((r_status_flags & PX4IO_P_STATUS_FLAGS_FMU_OK) || (!(r_status_flags & PX4IO_P_STATUS_FLAGS_FMU_OK) && (r_setup_arming & PX4IO_P_SETUP_ARMING_MANUAL_OVERRIDE_OK) ))
@@ -225,7 +246,7 @@ mixer_callback(uintptr_t handle,
 
 	case MIX_FAILSAFE:
 	case MIX_NONE:
-		/* XXX we could allow for configuration of per-output failsafe values */
+		control = 0.0f;
 		return -1;
 	}
 
@@ -273,8 +294,7 @@ mixer_handle_text(const void *buffer, size_t length)
 	case F2I_MIXER_ACTION_APPEND:
 		isr_debug(2, "append %d", length);
 
-		/* check for overflow - this is really fatal */
-		/* XXX could add just what will fit & try to parse, then repeat... */
+		/* check for overflow - this would be really fatal */
 		if ((mixer_text_length + text_length + 1) > sizeof(mixer_text)) {
 			r_status_flags &= ~PX4IO_P_STATUS_FLAGS_MIXER_OK;
 			return;
@@ -293,8 +313,13 @@ mixer_handle_text(const void *buffer, size_t length)
 		/* if anything was parsed */
 		if (resid != mixer_text_length) {
 
-			/* ideally, this should test resid == 0 ? */
-			r_status_flags |= PX4IO_P_STATUS_FLAGS_MIXER_OK;
+			/* only set mixer ok if no residual is left over */
+			if (resid == 0) {
+				r_status_flags |= PX4IO_P_STATUS_FLAGS_MIXER_OK;
+			} else {
+				/* not yet reached the end of the mixer, set as not ok */
+				r_status_flags &= ~PX4IO_P_STATUS_FLAGS_MIXER_OK;
+			}
 
 			isr_debug(2, "used %u", mixer_text_length - resid);
 
@@ -303,8 +328,43 @@ mixer_handle_text(const void *buffer, size_t length)
 				memcpy(&mixer_text[0], &mixer_text[mixer_text_length - resid], resid);
 
 			mixer_text_length = resid;
+
+			/* update failsafe values */
+			mixer_set_failsafe();
 		}
 
 		break;
 	}
 }
+
+static void
+mixer_set_failsafe()
+{
+	/* 
+	 * Check if a custom failsafe value has been written,
+	 * or if the mixer is not ok and bail out.
+	 */
+	if ((r_setup_arming & PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM) ||
+		!(r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK))
+		return;
+
+	/* set failsafe defaults to the values for all inputs = 0 */
+	float	outputs[IO_SERVO_COUNT];
+	unsigned mixed;
+
+	/* mix */
+	mixed = mixer_group.mix(&outputs[0], IO_SERVO_COUNT);
+
+	/* scale to PWM and update the servo outputs as required */
+	for (unsigned i = 0; i < mixed; i++) {
+
+		/* scale to servo output */
+		r_page_servo_failsafe[i] = (outputs[i] * 600.0f) + 1500;
+
+	}
+
+	/* disable the rest of the outputs */
+	for (unsigned i = mixed; i < IO_SERVO_COUNT; i++)
+		r_page_servo_failsafe[i] = 0;
+
+}
diff --git a/src/modules/px4iofirmware/protocol.h b/src/modules/px4iofirmware/protocol.h
index 6cdf86b2b..90d63ea1a 100644
--- a/src/modules/px4iofirmware/protocol.h
+++ b/src/modules/px4iofirmware/protocol.h
@@ -111,7 +111,7 @@
 #define PX4IO_P_CONFIG_ACTUATOR_COUNT		5	/* hardcoded max actuator output count */
 #define PX4IO_P_CONFIG_RC_INPUT_COUNT		6	/* hardcoded max R/C input count supported */
 #define PX4IO_P_CONFIG_ADC_INPUT_COUNT		7	/* hardcoded max ADC inputs */
-#define PX4IO_P_CONFIG_RELAY_COUNT		8	/* harcoded # of relay outputs */
+#define PX4IO_P_CONFIG_RELAY_COUNT		8	/* hardcoded # of relay outputs */
 
 /* dynamic status page */
 #define PX4IO_PAGE_STATUS		1
@@ -130,6 +130,7 @@
 #define PX4IO_P_STATUS_FLAGS_MIXER_OK		(1 << 8) /* mixer is OK */
 #define PX4IO_P_STATUS_FLAGS_ARM_SYNC		(1 << 9) /* the arming state between IO and FMU is in sync */
 #define PX4IO_P_STATUS_FLAGS_INIT_OK		(1 << 10) /* initialisation of the IO completed without error */
+#define PX4IO_P_STATUS_FLAGS_FAILSAFE		(1 << 11) /* failsafe is active */
 
 #define PX4IO_P_STATUS_ALARMS			3	 /* alarm flags - alarms latch, write 1 to a bit to clear it */
 #define PX4IO_P_STATUS_ALARMS_VBATT_LOW		(1 << 0) /* VBatt is very close to regulator dropout */
@@ -174,6 +175,7 @@
 #define PX4IO_P_SETUP_ARMING_IO_ARM_OK		(1 << 0) /* OK to arm the IO side */
 #define PX4IO_P_SETUP_ARMING_FMU_ARMED		(1 << 1) /* FMU is already armed */
 #define PX4IO_P_SETUP_ARMING_MANUAL_OVERRIDE_OK	(1 << 2) /* OK to switch to manual override via override RC channel */
+#define PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM	(1 << 3) /* use custom failsafe values, not 0 values of mixer */
 #define PX4IO_P_SETUP_ARMING_INAIR_RESTART_OK	(1 << 4) /* OK to try in-air restart */
 
 #define PX4IO_P_SETUP_PWM_RATES			2	/* bitmask, 0 = low rate, 1 = high rate */
diff --git a/src/modules/px4iofirmware/registers.c b/src/modules/px4iofirmware/registers.c
index 9698a0f2f..df7d6dcd3 100644
--- a/src/modules/px4iofirmware/registers.c
+++ b/src/modules/px4iofirmware/registers.c
@@ -41,6 +41,7 @@
 
 #include <stdbool.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include <drivers/drv_hrt.h>
 
@@ -178,8 +179,10 @@ uint16_t		r_page_rc_input_config[MAX_CONTROL_CHANNELS * PX4IO_P_RC_CONFIG_STRIDE
  * PAGE 105
  *
  * Failsafe servo PWM values
+ * 
+ * Disable pulses as default.
  */
-uint16_t		r_page_servo_failsafe[IO_SERVO_COUNT];
+uint16_t		r_page_servo_failsafe[IO_SERVO_COUNT] = { 0 };
 
 void
 registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num_values)
@@ -230,11 +233,14 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 	case PX4IO_PAGE_FAILSAFE_PWM:
 
 		/* copy channel data */
-		while ((offset < PX4IO_CONTROL_CHANNELS) && (num_values > 0)) {
+		while ((offset < IO_SERVO_COUNT) && (num_values > 0)) {
 
 			/* XXX range-check value? */
 			r_page_servo_failsafe[offset] = *values;
 
+			/* flag the failsafe values as custom */
+			r_setup_arming |= PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM;
+
 			offset++;
 			num_values--;
 			values++;
diff --git a/src/modules/sdlog2/logbuffer.c b/src/modules/sdlog2/logbuffer.c
new file mode 100644
index 000000000..8aaafaf31
--- /dev/null
+++ b/src/modules/sdlog2/logbuffer.c
@@ -0,0 +1,134 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * 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 logbuffer.c
+ *
+ * Ring FIFO buffer for binary log data.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "logbuffer.h"
+
+int logbuffer_init(struct logbuffer_s *lb, int size)
+{
+	lb->size  = size;
+	lb->write_ptr = 0;
+	lb->read_ptr = 0;
+	lb->data = malloc(lb->size);
+	return (lb->data == 0) ? ERROR : OK;
+}
+
+int logbuffer_count(struct logbuffer_s *lb)
+{
+	int n = lb->write_ptr - lb->read_ptr;
+
+	if (n < 0) {
+		n += lb->size;
+	}
+
+	return n;
+}
+
+int logbuffer_is_empty(struct logbuffer_s *lb)
+{
+	return lb->read_ptr == lb->write_ptr;
+}
+
+bool logbuffer_write(struct logbuffer_s *lb, void *ptr, int size)
+{
+	// bytes available to write
+	int available = lb->read_ptr - lb->write_ptr - 1;
+
+	if (available < 0)
+		available += lb->size;
+
+	if (size > available) {
+		// buffer overflow
+		return false;
+	}
+
+	char *c = (char *) ptr;
+	int n = lb->size - lb->write_ptr;	// bytes to end of the buffer
+
+	if (n < size) {
+		// message goes over end of the buffer
+		memcpy(&(lb->data[lb->write_ptr]), c, n);
+		lb->write_ptr = 0;
+
+	} else {
+		n = 0;
+	}
+
+	// now: n = bytes already written
+	int p = size - n;	// number of bytes to write
+	memcpy(&(lb->data[lb->write_ptr]), &(c[n]), p);
+	lb->write_ptr = (lb->write_ptr + p) % lb->size;
+	return true;
+}
+
+int logbuffer_get_ptr(struct logbuffer_s *lb, void **ptr, bool *is_part)
+{
+	// bytes available to read
+	int available = lb->write_ptr - lb->read_ptr;
+
+	if (available == 0) {
+		return 0;	// buffer is empty
+	}
+
+	int n = 0;
+
+	if (available > 0) {
+		// read pointer is before write pointer, all available bytes can be read
+		n = available;
+		*is_part = false;
+
+	} else {
+		// read pointer is after write pointer, read bytes from read_ptr to end of the buffer
+		n = lb->size - lb->read_ptr;
+		*is_part = true;
+	}
+
+	*ptr = &(lb->data[lb->read_ptr]);
+	return n;
+}
+
+void logbuffer_mark_read(struct logbuffer_s *lb, int n)
+{
+	lb->read_ptr = (lb->read_ptr + n) % lb->size;
+}
diff --git a/src/modules/sdlog2/logbuffer.h b/src/modules/sdlog2/logbuffer.h
new file mode 100644
index 000000000..31521f722
--- /dev/null
+++ b/src/modules/sdlog2/logbuffer.h
@@ -0,0 +1,68 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * 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 logbuffer.h
+ *
+ * Ring FIFO buffer for binary log data.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#ifndef SDLOG2_RINGBUFFER_H_
+#define SDLOG2_RINGBUFFER_H_
+
+#include <stdbool.h>
+
+struct logbuffer_s {
+	// pointers and size are in bytes
+	int write_ptr;
+	int read_ptr;
+	int size;
+	char *data;
+};
+
+int logbuffer_init(struct logbuffer_s *lb, int size);
+
+int logbuffer_count(struct logbuffer_s *lb);
+
+int logbuffer_is_empty(struct logbuffer_s *lb);
+
+bool logbuffer_write(struct logbuffer_s *lb, void *ptr, int size);
+
+int logbuffer_get_ptr(struct logbuffer_s *lb, void **ptr, bool *is_part);
+
+void logbuffer_mark_read(struct logbuffer_s *lb, int n);
+
+#endif
diff --git a/src/modules/sdlog2/module.mk b/src/modules/sdlog2/module.mk
new file mode 100644
index 000000000..f53129688
--- /dev/null
+++ b/src/modules/sdlog2/module.mk
@@ -0,0 +1,43 @@
+############################################################################
+#
+#   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
+# 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.
+#
+############################################################################
+
+#
+# sdlog2 Application
+#
+
+MODULE_COMMAND  = sdlog2
+# The main thread only buffers to RAM, needs a high priority
+MODULE_PRIORITY = "SCHED_PRIORITY_MAX-30"
+
+SRCS = sdlog2.c \
+       logbuffer.c
diff --git a/src/modules/sdlog2/sdlog2.c b/src/modules/sdlog2/sdlog2.c
new file mode 100644
index 000000000..a14bd6f80
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2.c
@@ -0,0 +1,1178 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+ *   Author: Lorenz Meier <lm@inf.ethz.ch>
+ *           Anton Babushkin <rk3dov@gmail.com>
+ *
+ * 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 sdlog2.c
+ *
+ * Simple SD logger for flight data. Buffers new sensor values and
+ * does the heavy SD I/O in a low-priority worker thread.
+ *
+ * @author Lorenz Meier <lm@inf.ethz.ch>
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/prctl.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <systemlib/err.h>
+#include <unistd.h>
+#include <drivers/drv_hrt.h>
+
+#include <uORB/uORB.h>
+#include <uORB/topics/vehicle_status.h>
+#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/vehicle_attitude.h>
+#include <uORB/topics/vehicle_attitude_setpoint.h>
+#include <uORB/topics/actuator_outputs.h>
+#include <uORB/topics/actuator_controls.h>
+#include <uORB/topics/actuator_controls_effective.h>
+#include <uORB/topics/vehicle_command.h>
+#include <uORB/topics/vehicle_local_position.h>
+#include <uORB/topics/vehicle_local_position_setpoint.h>
+#include <uORB/topics/vehicle_global_position.h>
+#include <uORB/topics/vehicle_gps_position.h>
+#include <uORB/topics/vehicle_vicon_position.h>
+#include <uORB/topics/optical_flow.h>
+#include <uORB/topics/battery_status.h>
+#include <uORB/topics/differential_pressure.h>
+#include <uORB/topics/airspeed.h>
+#include <uORB/topics/rc_channels.h>
+
+#include <systemlib/systemlib.h>
+
+#include <mavlink/mavlink_log.h>
+
+#include "logbuffer.h"
+#include "sdlog2_format.h"
+#include "sdlog2_messages.h"
+
+#define LOGBUFFER_WRITE_AND_COUNT(_msg) if (logbuffer_write(&lb, &log_msg, LOG_PACKET_SIZE(_msg))) { \
+		log_msgs_written++; \
+	} else { \
+		log_msgs_skipped++; \
+		/*printf("skip\n");*/ \
+	}
+
+#define LOG_ORB_SUBSCRIBE(_var, _topic) subs.##_var##_sub = orb_subscribe(ORB_ID(##_topic##)); \
+	fds[fdsc_count].fd = subs.##_var##_sub; \
+	fds[fdsc_count].events = POLLIN; \
+	fdsc_count++;
+
+
+//#define SDLOG2_DEBUG
+
+static bool thread_should_exit = false;		/**< Deamon exit flag */
+static bool thread_running = false;			/**< Deamon status flag */
+static int deamon_task;						/**< Handle of deamon task / thread */
+static bool logwriter_should_exit = false;	/**< Logwriter thread exit flag */
+static const int MAX_NO_LOGFOLDER = 999;	/**< Maximum number of log folders */
+static const int MAX_NO_LOGFILE = 999;		/**< Maximum number of log files */
+static const int LOG_BUFFER_SIZE_DEFAULT = 8192;
+static const int MAX_WRITE_CHUNK = 512;
+static const int MIN_BYTES_TO_WRITE = 512;
+
+static const char *mountpoint = "/fs/microsd";
+int log_file = -1;
+int mavlink_fd = -1;
+struct logbuffer_s lb;
+
+/* mutex / condition to synchronize threads */
+pthread_mutex_t logbuffer_mutex;
+pthread_cond_t logbuffer_cond;
+
+char folder_path[64];
+
+/* statistics counters */
+unsigned long log_bytes_written = 0;
+uint64_t start_time = 0;
+unsigned long log_msgs_written = 0;
+unsigned long log_msgs_skipped = 0;
+
+/* current state of logging */
+bool logging_enabled = false;
+/* enable logging on start (-e option) */
+bool log_on_start = false;
+/* enable logging when armed (-a option) */
+bool log_when_armed = false;
+/* delay = 1 / rate (rate defined by -r option) */
+useconds_t sleep_delay = 0;
+
+/* helper flag to track system state changes */
+bool flag_system_armed = false;
+
+pthread_t logwriter_pthread = 0;
+
+/**
+ * Log buffer writing thread. Open and close file here.
+ */
+static void *logwriter_thread(void *arg);
+
+/**
+ * SD log management function.
+ */
+__EXPORT int sdlog2_main(int argc, char *argv[]);
+
+/**
+ * Mainloop of sd log deamon.
+ */
+int sdlog2_thread_main(int argc, char *argv[]);
+
+/**
+ * Print the correct usage.
+ */
+static void sdlog2_usage(const char *reason);
+
+/**
+ * Print the current status.
+ */
+static void sdlog2_status(void);
+
+/**
+ * Start logging: create new file and start log writer thread.
+ */
+void sdlog2_start_log();
+
+/**
+ * Stop logging: stop log writer thread and close log file.
+ */
+void sdlog2_stop_log();
+
+/**
+ * Write a header to log file: list of message formats.
+ */
+void write_formats(int fd);
+
+
+static bool file_exist(const char *filename);
+
+static int file_copy(const char *file_old, const char *file_new);
+
+static void handle_command(struct vehicle_command_s *cmd);
+
+static void handle_status(struct vehicle_status_s *cmd);
+
+/**
+ * Create folder for current logging session. Store folder name in 'log_folder'.
+ */
+static int create_logfolder();
+
+/**
+ * Select first free log file name and open it.
+ */
+static int open_logfile();
+
+static void
+sdlog2_usage(const char *reason)
+{
+	if (reason)
+		fprintf(stderr, "%s\n", reason);
+
+	errx(1, "usage: sdlog2 {start|stop|status} [-r <log rate>] [-b <buffer size>] -e -a\n"
+	     "\t-r\tLog rate in Hz, 0 means unlimited rate\n"
+	     "\t-b\tLog buffer size in KiB, default is 8\n"
+	     "\t-e\tEnable logging by default (if not, can be started by command)\n"
+	     "\t-a\tLog only when armed (can be still overriden by command)\n");
+}
+
+/**
+ * The logger deamon app only briefly exists to start
+ * the background job. The stack size assigned in the
+ * Makefile does only apply to this management task.
+ *
+ * The actual stack size should be set in the call
+ * to task_spawn().
+ */
+int sdlog2_main(int argc, char *argv[])
+{
+	if (argc < 2)
+		sdlog2_usage("missing command");
+
+	if (!strcmp(argv[1], "start")) {
+
+		if (thread_running) {
+			printf("sdlog2 already running\n");
+			/* this is not an error */
+			exit(0);
+		}
+
+		thread_should_exit = false;
+		deamon_task = task_spawn("sdlog2",
+					 SCHED_DEFAULT,
+					 SCHED_PRIORITY_DEFAULT - 30,
+					 2048,
+					 sdlog2_thread_main,
+					 (const char **)argv);
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		if (!thread_running) {
+			printf("\tsdlog2 is not started\n");
+		}
+
+		thread_should_exit = true;
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (thread_running) {
+			sdlog2_status();
+
+		} else {
+			printf("\tsdlog2 not started\n");
+		}
+
+		exit(0);
+	}
+
+	sdlog2_usage("unrecognized command");
+	exit(1);
+}
+
+int create_logfolder()
+{
+	/* make folder on sdcard */
+	uint16_t folder_number = 1; // start with folder sess001
+	int mkdir_ret;
+
+	/* look for the next folder that does not exist */
+	while (folder_number <= MAX_NO_LOGFOLDER) {
+		/* set up folder path: e.g. /fs/microsd/sess001 */
+		sprintf(folder_path, "%s/sess%03u", mountpoint, folder_number);
+		mkdir_ret = mkdir(folder_path, S_IRWXU | S_IRWXG | S_IRWXO);
+		/* the result is -1 if the folder exists */
+
+		if (mkdir_ret == 0) {
+			/* folder does not exist, success */
+
+			/* copy parser script file */
+			// TODO
+			/*
+			char mfile_out[100];
+			sprintf(mfile_out, "%s/session%04u/run_to_plot_data.m", mountpoint, foldernumber);
+			int ret = file_copy(mfile_in, mfile_out);
+
+			if (!ret) {
+				warnx("copied m file to %s", mfile_out);
+
+			} else {
+				warnx("failed copying m file from %s to\n %s", mfile_in, mfile_out);
+			}
+			*/
+
+			break;
+
+		} else if (mkdir_ret == -1) {
+			/* folder exists already */
+			folder_number++;
+			continue;
+
+		} else {
+			warn("failed creating new folder");
+			return -1;
+		}
+	}
+
+	if (folder_number >= MAX_NO_LOGFOLDER) {
+		/* we should not end up here, either we have more than MAX_NO_LOGFOLDER on the SD card, or another problem */
+		warnx("all %d possible folders exist already.", MAX_NO_LOGFOLDER);
+		return -1;
+	}
+
+	return 0;
+}
+
+int open_logfile()
+{
+	/* make folder on sdcard */
+	uint16_t file_number = 1; // start with file log001
+
+	/* string to hold the path to the log */
+	char path_buf[64] = "";
+
+	int fd = 0;
+
+	/* look for the next file that does not exist */
+	while (file_number <= MAX_NO_LOGFILE) {
+		/* set up file path: e.g. /fs/microsd/sess001/log001.bin */
+		sprintf(path_buf, "%s/log%03u.bin", folder_path, file_number);
+
+		if (file_exist(path_buf)) {
+			file_number++;
+			continue;
+		}
+
+		fd = open(path_buf, O_CREAT | O_WRONLY | O_DSYNC);
+
+		if (fd == 0) {
+			errx(1, "opening %s failed.", path_buf);
+		}
+
+		warnx("logging to: %s", path_buf);
+		mavlink_log_info(mavlink_fd, "[sdlog2] log: %s", path_buf);
+
+		return fd;
+	}
+
+	if (file_number > MAX_NO_LOGFILE) {
+		/* we should not end up here, either we have more than MAX_NO_LOGFILE on the SD card, or another problem */
+		warn("all %d possible files exist already", MAX_NO_LOGFILE);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void *logwriter_thread(void *arg)
+{
+	/* set name */
+	prctl(PR_SET_NAME, "sdlog2_writer", 0);
+
+	struct logbuffer_s *logbuf = (struct logbuffer_s *)arg;
+
+	int log_file = open_logfile();
+
+	/* write log messages formats */
+	write_formats(log_file);
+
+	int poll_count = 0;
+
+	void *read_ptr;
+	int n = 0;
+	bool should_wait = false;
+	bool is_part = false;
+
+	while (!thread_should_exit && !logwriter_should_exit) {
+
+		/* make sure threads are synchronized */
+		pthread_mutex_lock(&logbuffer_mutex);
+
+		/* update read pointer if needed */
+		if (n > 0) {
+			logbuffer_mark_read(&lb, n);
+		}
+
+		/* only wait if no data is available to process */
+		if (should_wait) {
+			/* blocking wait for new data at this line */
+			pthread_cond_wait(&logbuffer_cond, &logbuffer_mutex);
+		}
+
+		/* only get pointer to thread-safe data, do heavy I/O a few lines down */
+		int available = logbuffer_get_ptr(logbuf, &read_ptr, &is_part);
+
+		/* continue */
+		pthread_mutex_unlock(&logbuffer_mutex);
+
+		if (available > 0) {
+			/* do heavy IO here */
+			if (available > MAX_WRITE_CHUNK) {
+				n = MAX_WRITE_CHUNK;
+
+			} else {
+				n = available;
+			}
+
+			n = write(log_file, read_ptr, n);
+
+			should_wait = (n == available) && !is_part;
+#ifdef SDLOG2_DEBUG
+			printf("%i wrote: %i of %i, is_part=%i, should_wait=%i", poll_count, n, available, (int)is_part, (int)should_wait);
+#endif
+
+			if (n < 0) {
+				thread_should_exit = true;
+				err(1, "error writing log file");
+			}
+
+			if (n > 0) {
+				log_bytes_written += n;
+			}
+
+		} else {
+			should_wait = true;
+		}
+
+		if (poll_count % 10 == 0) {
+			fsync(log_file);
+		}
+
+		poll_count++;
+	}
+
+	fsync(log_file);
+	close(log_file);
+
+	return OK;
+}
+
+void sdlog2_start_log()
+{
+	warnx("start logging.");
+	mavlink_log_info(mavlink_fd, "[sdlog2] start logging");
+
+	/* initialize statistics counter */
+	log_bytes_written = 0;
+	start_time = hrt_absolute_time();
+	log_msgs_written = 0;
+	log_msgs_skipped = 0;
+
+	/* initialize log buffer emptying thread */
+	pthread_attr_t receiveloop_attr;
+	pthread_attr_init(&receiveloop_attr);
+
+	struct sched_param param;
+	/* low priority, as this is expensive disk I/O */
+	param.sched_priority = SCHED_PRIORITY_DEFAULT - 40;
+	(void)pthread_attr_setschedparam(&receiveloop_attr, &param);
+
+	pthread_attr_setstacksize(&receiveloop_attr, 2048);
+
+	logwriter_should_exit = false;
+	pthread_t thread;
+
+	/* start log buffer emptying thread */
+	if (0 != pthread_create(&thread, &receiveloop_attr, logwriter_thread, &lb)) {
+		errx(1, "error creating logwriter thread");
+	}
+
+	logging_enabled = true;
+	// XXX we have to destroy the attr at some point
+}
+
+void sdlog2_stop_log()
+{
+	warnx("stop logging.");
+	mavlink_log_info(mavlink_fd, "[sdlog2] stop logging");
+
+	logging_enabled = false;
+	logwriter_should_exit = true;
+
+	/* wake up write thread one last time */
+	pthread_mutex_lock(&logbuffer_mutex);
+	pthread_cond_signal(&logbuffer_cond);
+	/* unlock, now the writer thread may return */
+	pthread_mutex_unlock(&logbuffer_mutex);
+
+	/* wait for write thread to return */
+	(void)pthread_join(logwriter_pthread, NULL);
+
+	sdlog2_status();
+}
+
+
+void write_formats(int fd)
+{
+	/* construct message format packet */
+	struct {
+		LOG_PACKET_HEADER;
+		struct log_format_s body;
+	} log_format_packet = {
+		LOG_PACKET_HEADER_INIT(LOG_FORMAT_MSG),
+	};
+
+	/* fill message format packet for each format and write to log */
+	int i;
+
+	for (i = 0; i < log_formats_num; i++) {
+		log_format_packet.body = log_formats[i];
+		write(fd, &log_format_packet, sizeof(log_format_packet));
+	}
+
+	fsync(fd);
+}
+
+int sdlog2_thread_main(int argc, char *argv[])
+{
+	mavlink_fd = open(MAVLINK_LOG_DEVICE, 0);
+
+	if (mavlink_fd < 0) {
+		warnx("failed to open MAVLink log stream, start mavlink app first.");
+	}
+
+	/* log buffer size */
+	int log_buffer_size = LOG_BUFFER_SIZE_DEFAULT;
+
+	/* work around some stupidity in task_create's argv handling */
+	argc -= 2;
+	argv += 2;
+	int ch;
+
+	while ((ch = getopt(argc, argv, "r:b:ea")) != EOF) {
+		switch (ch) {
+		case 'r': {
+				unsigned long r = strtoul(optarg, NULL, 10);
+
+				if (r == 0) {
+					sleep_delay = 0;
+
+				} else {
+					sleep_delay = 1000000 / r;
+				}
+			}
+			break;
+
+		case 'b': {
+				unsigned long s = strtoul(optarg, NULL, 10);
+
+				if (s < 1) {
+					s = 1;
+				}
+
+				log_buffer_size = 1024 * s;
+			}
+			break;
+
+		case 'e':
+			log_on_start = true;
+			break;
+
+		case 'a':
+			log_when_armed = true;
+			break;
+
+		case '?':
+			if (optopt == 'c') {
+				warnx("Option -%c requires an argument.", optopt);
+
+			} else if (isprint(optopt)) {
+				warnx("Unknown option `-%c'.", optopt);
+
+			} else {
+				warnx("Unknown option character `\\x%x'.", optopt);
+			}
+
+		default:
+			sdlog2_usage("unrecognized flag");
+			errx(1, "exiting.");
+		}
+	}
+
+	if (!file_exist(mountpoint)) {
+		errx(1, "logging mount point %s not present, exiting.", mountpoint);
+	}
+
+	if (create_logfolder()) {
+		errx(1, "unable to create logging folder, exiting.");
+	}
+
+	/* only print logging path, important to find log file later */
+	warnx("logging to directory: %s", folder_path);
+
+	/* initialize log buffer with specified size */
+	warnx("log buffer size: %i bytes.", log_buffer_size);
+
+	if (OK != logbuffer_init(&lb, log_buffer_size)) {
+		errx(1, "can't allocate log buffer, exiting.");
+	}
+
+	/* file descriptors to wait for */
+	struct pollfd fds_control[2];
+
+	/* --- IMPORTANT: DEFINE NUMBER OF ORB STRUCTS TO WAIT FOR HERE --- */
+	/* number of messages */
+	const ssize_t fdsc = 15;
+	/* Sanity check variable and index */
+	ssize_t fdsc_count = 0;
+	/* file descriptors to wait for */
+	struct pollfd fds[fdsc];
+
+	struct vehicle_status_s buf_status;
+	memset(&buf_status, 0, sizeof(buf_status));
+
+	/* warning! using union here to save memory, elements should be used separately! */
+	union {
+		struct vehicle_command_s cmd;
+		struct sensor_combined_s sensor;
+		struct vehicle_attitude_s att;
+		struct vehicle_attitude_setpoint_s att_sp;
+		struct actuator_outputs_s act_outputs;
+		struct actuator_controls_s act_controls;
+		struct actuator_controls_effective_s act_controls_effective;
+		struct vehicle_local_position_s local_pos;
+		struct vehicle_local_position_setpoint_s local_pos_sp;
+		struct vehicle_global_position_s global_pos;
+		struct vehicle_gps_position_s gps_pos;
+		struct vehicle_vicon_position_s vicon_pos;
+		struct optical_flow_s flow;
+		struct rc_channels_s rc;
+		struct differential_pressure_s diff_pres;
+		struct airspeed_s airspeed;
+	} buf;
+	memset(&buf, 0, sizeof(buf));
+
+	struct {
+		int cmd_sub;
+		int status_sub;
+		int sensor_sub;
+		int att_sub;
+		int att_sp_sub;
+		int act_outputs_sub;
+		int act_controls_sub;
+		int act_controls_effective_sub;
+		int local_pos_sub;
+		int local_pos_sp_sub;
+		int global_pos_sub;
+		int gps_pos_sub;
+		int vicon_pos_sub;
+		int flow_sub;
+		int rc_sub;
+	} subs;
+
+	/* log message buffer: header + body */
+#pragma pack(push, 1)
+	struct {
+		LOG_PACKET_HEADER;
+		union {
+			struct log_TIME_s log_TIME;
+			struct log_ATT_s log_ATT;
+			struct log_ATSP_s log_ATSP;
+			struct log_IMU_s log_IMU;
+			struct log_SENS_s log_SENS;
+			struct log_LPOS_s log_LPOS;
+			struct log_LPSP_s log_LPSP;
+			struct log_GPS_s log_GPS;
+			struct log_ATTC_s log_ATTC;
+			struct log_STAT_s log_STAT;
+			struct log_RC_s log_RC;
+			struct log_OUT0_s log_OUT0;
+		} body;
+	} log_msg = {
+		LOG_PACKET_HEADER_INIT(0)
+	};
+#pragma pack(pop)
+	memset(&log_msg.body, 0, sizeof(log_msg.body));
+
+	/* --- VEHICLE COMMAND --- */
+	subs.cmd_sub = orb_subscribe(ORB_ID(vehicle_command));
+	fds[fdsc_count].fd = subs.cmd_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- VEHICLE STATUS --- */
+	subs.status_sub = orb_subscribe(ORB_ID(vehicle_status));
+	fds[fdsc_count].fd = subs.status_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- GPS POSITION --- */
+	subs.gps_pos_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
+	fds[fdsc_count].fd = subs.gps_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- SENSORS COMBINED --- */
+	subs.sensor_sub = orb_subscribe(ORB_ID(sensor_combined));
+	fds[fdsc_count].fd = subs.sensor_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ATTITUDE --- */
+	subs.att_sub = orb_subscribe(ORB_ID(vehicle_attitude));
+	fds[fdsc_count].fd = subs.att_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ATTITUDE SETPOINT --- */
+	subs.att_sp_sub = orb_subscribe(ORB_ID(vehicle_attitude_setpoint));
+	fds[fdsc_count].fd = subs.att_sp_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ACTUATOR OUTPUTS --- */
+	subs.act_outputs_sub = orb_subscribe(ORB_ID_VEHICLE_CONTROLS);
+	fds[fdsc_count].fd = subs.act_outputs_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ACTUATOR CONTROL --- */
+	subs.act_controls_sub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS);
+	fds[fdsc_count].fd = subs.act_controls_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- ACTUATOR CONTROL EFFECTIVE --- */
+	subs.act_controls_effective_sub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS_EFFECTIVE);
+	fds[fdsc_count].fd = subs.act_controls_effective_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- LOCAL POSITION --- */
+	subs.local_pos_sub = orb_subscribe(ORB_ID(vehicle_local_position));
+	fds[fdsc_count].fd = subs.local_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- LOCAL POSITION SETPOINT --- */
+	subs.local_pos_sp_sub = orb_subscribe(ORB_ID(vehicle_local_position_setpoint));
+	fds[fdsc_count].fd = subs.local_pos_sp_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- GLOBAL POSITION --- */
+	subs.global_pos_sub = orb_subscribe(ORB_ID(vehicle_global_position));
+	fds[fdsc_count].fd = subs.global_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- VICON POSITION --- */
+	subs.vicon_pos_sub = orb_subscribe(ORB_ID(vehicle_vicon_position));
+	fds[fdsc_count].fd = subs.vicon_pos_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- OPTICAL FLOW --- */
+	subs.flow_sub = orb_subscribe(ORB_ID(optical_flow));
+	fds[fdsc_count].fd = subs.flow_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* --- RC CHANNELS --- */
+	subs.rc_sub = orb_subscribe(ORB_ID(rc_channels));
+	fds[fdsc_count].fd = subs.rc_sub;
+	fds[fdsc_count].events = POLLIN;
+	fdsc_count++;
+
+	/* WARNING: If you get the error message below,
+	 * then the number of registered messages (fdsc)
+	 * differs from the number of messages in the above list.
+	 */
+	if (fdsc_count > fdsc) {
+		warn("WARNING: Not enough space for poll fds allocated. Check %s:%d.", __FILE__, __LINE__);
+		fdsc_count = fdsc;
+	}
+
+	/*
+	 * set up poll to block for new data,
+	 * wait for a maximum of 1000 ms
+	 */
+	const int poll_timeout = 1000;
+
+	thread_running = true;
+
+	/* initialize thread synchronization */
+	pthread_mutex_init(&logbuffer_mutex, NULL);
+	pthread_cond_init(&logbuffer_cond, NULL);
+
+	/* track changes in sensor_combined topic */
+	uint16_t gyro_counter = 0;
+	uint16_t accelerometer_counter = 0;
+	uint16_t magnetometer_counter = 0;
+	uint16_t baro_counter = 0;
+	uint16_t differential_pressure_counter = 0;
+
+	/* enable logging on start if needed */
+	if (log_on_start)
+		sdlog2_start_log();
+
+	while (!thread_should_exit) {
+		/* decide use usleep() or blocking poll() */
+		bool use_sleep = sleep_delay > 0 && logging_enabled;
+
+		/* poll all topics if logging enabled or only management (first 2) if not */
+		int poll_ret = poll(fds, logging_enabled ? fdsc_count : 2, use_sleep ? 0 : poll_timeout);
+
+		/* handle the poll result */
+		if (poll_ret < 0) {
+			warnx("ERROR: poll error, stop logging.");
+			thread_should_exit = true;
+
+		} else if (poll_ret > 0) {
+
+			/* check all data subscriptions only if logging enabled,
+			 * logging_enabled can be changed while checking vehicle_command and vehicle_status */
+			bool check_data = logging_enabled;
+			int ifds = 0;
+			int handled_topics = 0;
+
+			/* --- VEHICLE COMMAND - LOG MANAGEMENT --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_command), subs.cmd_sub, &buf.cmd);
+				handle_command(&buf.cmd);
+				handled_topics++;
+			}
+
+			/* --- VEHICLE STATUS - LOG MANAGEMENT --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_status), subs.status_sub, &buf_status);
+
+				if (log_when_armed) {
+					handle_status(&buf_status);
+				}
+
+				handled_topics++;
+			}
+
+			if (!logging_enabled || !check_data || handled_topics >= poll_ret) {
+				continue;
+			}
+
+			ifds = 1;	// Begin from fds[1] again
+
+			pthread_mutex_lock(&logbuffer_mutex);
+
+			/* write time stamp message */
+			log_msg.msg_type = LOG_TIME_MSG;
+			log_msg.body.log_TIME.t = hrt_absolute_time();
+			LOGBUFFER_WRITE_AND_COUNT(TIME);
+
+			/* --- VEHICLE STATUS --- */
+			if (fds[ifds++].revents & POLLIN) {
+				// Don't orb_copy, it's already done few lines above
+				log_msg.msg_type = LOG_STAT_MSG;
+				log_msg.body.log_STAT.state = (unsigned char) buf_status.state_machine;
+				log_msg.body.log_STAT.flight_mode = (unsigned char) buf_status.flight_mode;
+				log_msg.body.log_STAT.manual_control_mode = (unsigned char) buf_status.manual_control_mode;
+				log_msg.body.log_STAT.manual_sas_mode = (unsigned char) buf_status.manual_sas_mode;
+				log_msg.body.log_STAT.armed = (unsigned char) buf_status.flag_system_armed;
+				log_msg.body.log_STAT.battery_voltage = buf_status.voltage_battery;
+				log_msg.body.log_STAT.battery_current = buf_status.current_battery;
+				log_msg.body.log_STAT.battery_remaining = buf_status.battery_remaining;
+				log_msg.body.log_STAT.battery_warning = (unsigned char) buf_status.battery_warning;
+				LOGBUFFER_WRITE_AND_COUNT(STAT);
+			}
+
+			/* --- GPS POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_gps_position), subs.gps_pos_sub, &buf.gps_pos);
+				log_msg.msg_type = LOG_GPS_MSG;
+				log_msg.body.log_GPS.gps_time = buf.gps_pos.time_gps_usec;
+				log_msg.body.log_GPS.fix_type = buf.gps_pos.fix_type;
+				log_msg.body.log_GPS.eph = buf.gps_pos.eph_m;
+				log_msg.body.log_GPS.epv = buf.gps_pos.epv_m;
+				log_msg.body.log_GPS.lat = buf.gps_pos.lat;
+				log_msg.body.log_GPS.lon = buf.gps_pos.lon;
+				log_msg.body.log_GPS.alt = buf.gps_pos.alt * 0.001;
+				log_msg.body.log_GPS.vel_n = buf.gps_pos.vel_n_m_s;
+				log_msg.body.log_GPS.vel_e = buf.gps_pos.vel_e_m_s;
+				log_msg.body.log_GPS.vel_d = buf.gps_pos.vel_d_m_s;
+				log_msg.body.log_GPS.cog = buf.gps_pos.cog_rad;
+				LOGBUFFER_WRITE_AND_COUNT(GPS);
+			}
+
+			/* --- SENSOR COMBINED --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(sensor_combined), subs.sensor_sub, &buf.sensor);
+				bool write_IMU = false;
+				bool write_SENS = false;
+
+				if (buf.sensor.gyro_counter != gyro_counter) {
+					gyro_counter = buf.sensor.gyro_counter;
+					write_IMU = true;
+				}
+
+				if (buf.sensor.accelerometer_counter != accelerometer_counter) {
+					accelerometer_counter = buf.sensor.accelerometer_counter;
+					write_IMU = true;
+				}
+
+				if (buf.sensor.magnetometer_counter != magnetometer_counter) {
+					magnetometer_counter = buf.sensor.magnetometer_counter;
+					write_IMU = true;
+				}
+
+				if (buf.sensor.baro_counter != baro_counter) {
+					baro_counter = buf.sensor.baro_counter;
+					write_SENS = true;
+				}
+
+				if (buf.sensor.differential_pressure_counter != differential_pressure_counter) {
+					differential_pressure_counter = buf.sensor.differential_pressure_counter;
+					write_SENS = true;
+				}
+
+				if (write_IMU) {
+					log_msg.msg_type = LOG_IMU_MSG;
+					log_msg.body.log_IMU.gyro_x = buf.sensor.gyro_rad_s[0];
+					log_msg.body.log_IMU.gyro_y = buf.sensor.gyro_rad_s[1];
+					log_msg.body.log_IMU.gyro_z = buf.sensor.gyro_rad_s[2];
+					log_msg.body.log_IMU.acc_x = buf.sensor.accelerometer_m_s2[0];
+					log_msg.body.log_IMU.acc_y = buf.sensor.accelerometer_m_s2[1];
+					log_msg.body.log_IMU.acc_z = buf.sensor.accelerometer_m_s2[2];
+					log_msg.body.log_IMU.mag_x = buf.sensor.magnetometer_ga[0];
+					log_msg.body.log_IMU.mag_y = buf.sensor.magnetometer_ga[1];
+					log_msg.body.log_IMU.mag_z = buf.sensor.magnetometer_ga[2];
+					LOGBUFFER_WRITE_AND_COUNT(IMU);
+				}
+
+				if (write_SENS) {
+					log_msg.msg_type = LOG_SENS_MSG;
+					log_msg.body.log_SENS.baro_pres = buf.sensor.baro_pres_mbar;
+					log_msg.body.log_SENS.baro_alt = buf.sensor.baro_alt_meter;
+					log_msg.body.log_SENS.baro_temp = buf.sensor.baro_temp_celcius;
+					log_msg.body.log_SENS.diff_pres = buf.sensor.differential_pressure_pa;
+					LOGBUFFER_WRITE_AND_COUNT(SENS);
+				}
+			}
+
+			/* --- ATTITUDE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_attitude), subs.att_sub, &buf.att);
+				log_msg.msg_type = LOG_ATT_MSG;
+				log_msg.body.log_ATT.roll = buf.att.roll;
+				log_msg.body.log_ATT.pitch = buf.att.pitch;
+				log_msg.body.log_ATT.yaw = buf.att.yaw;
+				LOGBUFFER_WRITE_AND_COUNT(ATT);
+			}
+
+			/* --- ATTITUDE SETPOINT --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_attitude_setpoint), subs.att_sp_sub, &buf.att_sp);
+				log_msg.msg_type = LOG_ATSP_MSG;
+				log_msg.body.log_ATSP.roll_sp = buf.att_sp.roll_body;
+				log_msg.body.log_ATSP.pitch_sp = buf.att_sp.pitch_body;
+				log_msg.body.log_ATSP.yaw_sp = buf.att_sp.yaw_body;
+				LOGBUFFER_WRITE_AND_COUNT(ATSP);
+			}
+
+			/* --- ACTUATOR OUTPUTS --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(actuator_outputs_0), subs.act_outputs_sub, &buf.act_outputs);
+				log_msg.msg_type = LOG_OUT0_MSG;
+				memcpy(log_msg.body.log_OUT0.output, buf.act_outputs.output, sizeof(log_msg.body.log_OUT0.output));
+				LOGBUFFER_WRITE_AND_COUNT(OUT0);
+			}
+
+			/* --- ACTUATOR CONTROL --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, subs.act_controls_sub, &buf.act_controls);
+				log_msg.msg_type = LOG_ATTC_MSG;
+				log_msg.body.log_ATTC.roll = buf.act_controls.control[0];
+				log_msg.body.log_ATTC.pitch = buf.act_controls.control[1];
+				log_msg.body.log_ATTC.yaw = buf.act_controls.control[2];
+				log_msg.body.log_ATTC.thrust = buf.act_controls.control[3];
+				LOGBUFFER_WRITE_AND_COUNT(ATTC);
+			}
+
+			/* --- ACTUATOR CONTROL EFFECTIVE --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID_VEHICLE_ATTITUDE_CONTROLS_EFFECTIVE, subs.act_controls_effective_sub, &buf.act_controls_effective);
+				// TODO not implemented yet
+			}
+
+			/* --- LOCAL POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_local_position), subs.local_pos_sub, &buf.local_pos);
+				log_msg.msg_type = LOG_LPOS_MSG;
+				log_msg.body.log_LPOS.x = buf.local_pos.x;
+				log_msg.body.log_LPOS.y = buf.local_pos.y;
+				log_msg.body.log_LPOS.z = buf.local_pos.z;
+				log_msg.body.log_LPOS.vx = buf.local_pos.vx;
+				log_msg.body.log_LPOS.vy = buf.local_pos.vy;
+				log_msg.body.log_LPOS.vz = buf.local_pos.vz;
+				log_msg.body.log_LPOS.hdg = buf.local_pos.hdg;
+				log_msg.body.log_LPOS.home_lat = buf.local_pos.home_lat;
+				log_msg.body.log_LPOS.home_lon = buf.local_pos.home_lon;
+				log_msg.body.log_LPOS.home_alt = buf.local_pos.home_alt;
+				LOGBUFFER_WRITE_AND_COUNT(LPOS);
+			}
+
+			/* --- LOCAL POSITION SETPOINT --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_local_position_setpoint), subs.local_pos_sp_sub, &buf.local_pos_sp);
+				log_msg.msg_type = LOG_LPSP_MSG;
+				log_msg.body.log_LPSP.x = buf.local_pos_sp.x;
+				log_msg.body.log_LPSP.y = buf.local_pos_sp.y;
+				log_msg.body.log_LPSP.z = buf.local_pos_sp.z;
+				log_msg.body.log_LPSP.yaw = buf.local_pos_sp.yaw;
+				LOGBUFFER_WRITE_AND_COUNT(LPSP);
+			}
+
+			/* --- GLOBAL POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_global_position), subs.global_pos_sub, &buf.global_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- VICON POSITION --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(vehicle_vicon_position), subs.vicon_pos_sub, &buf.vicon_pos);
+				// TODO not implemented yet
+			}
+
+			/* --- FLOW --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(optical_flow), subs.flow_sub, &buf.flow);
+				// TODO not implemented yet
+			}
+
+			/* --- RC CHANNELS --- */
+			if (fds[ifds++].revents & POLLIN) {
+				orb_copy(ORB_ID(rc_channels), subs.rc_sub, &buf.rc);
+				log_msg.msg_type = LOG_RC_MSG;
+				/* Copy only the first 8 channels of 14 */
+				memcpy(log_msg.body.log_RC.channel, buf.rc.chan, sizeof(log_msg.body.log_RC.channel));
+				LOGBUFFER_WRITE_AND_COUNT(RC);
+			}
+
+			/* signal the other thread new data, but not yet unlock */
+			if (logbuffer_count(&lb) > MIN_BYTES_TO_WRITE) {
+#ifdef SDLOG2_DEBUG
+				printf("signal %i", logbuffer_count(&lb));
+#endif
+				/* only request write if several packets can be written at once */
+				pthread_cond_signal(&logbuffer_cond);
+			}
+
+			/* unlock, now the writer thread may run */
+			pthread_mutex_unlock(&logbuffer_mutex);
+		}
+
+		if (use_sleep) {
+			usleep(sleep_delay);
+		}
+	}
+
+	if (logging_enabled)
+		sdlog2_stop_log();
+
+	pthread_mutex_destroy(&logbuffer_mutex);
+	pthread_cond_destroy(&logbuffer_cond);
+
+	warnx("exiting.");
+
+	thread_running = false;
+
+	return 0;
+}
+
+void sdlog2_status()
+{
+	float kibibytes = log_bytes_written / 1024.0f;
+	float mebibytes = kibibytes / 1024.0f;
+	float seconds = ((float)(hrt_absolute_time() - start_time)) / 1000000.0f;
+
+	warnx("wrote %lu msgs, %4.2f MiB (average %5.3f KiB/s), skipped %lu msgs.", log_msgs_written, (double)mebibytes, (double)(kibibytes / seconds), log_msgs_skipped);
+	mavlink_log_info(mavlink_fd, "[sdlog2] wrote %lu msgs, skipped %lu msgs.", log_msgs_written, log_msgs_skipped);
+}
+
+/**
+ * @return 0 if file exists
+ */
+bool file_exist(const char *filename)
+{
+	struct stat buffer;
+	return stat(filename, &buffer) == 0;
+}
+
+int file_copy(const char *file_old, const char *file_new)
+{
+	FILE *source, *target;
+	source = fopen(file_old, "r");
+	int ret = 0;
+
+	if (source == NULL) {
+		warnx("failed opening input file to copy.");
+		return 1;
+	}
+
+	target = fopen(file_new, "w");
+
+	if (target == NULL) {
+		fclose(source);
+		warnx("failed to open output file to copy.");
+		return 1;
+	}
+
+	char buf[128];
+	int nread;
+
+	while ((nread = fread(buf, 1, sizeof(buf), source)) > 0) {
+		ret = fwrite(buf, 1, nread, target);
+
+		if (ret <= 0) {
+			warnx("error writing file.");
+			ret = 1;
+			break;
+		}
+	}
+
+	fsync(fileno(target));
+
+	fclose(source);
+	fclose(target);
+
+	return ret;
+}
+
+void handle_command(struct vehicle_command_s *cmd)
+{
+	/* result of the command */
+	uint8_t result = VEHICLE_CMD_RESULT_UNSUPPORTED;
+	int param;
+
+	/* request to set different system mode */
+	switch (cmd->command) {
+
+	case VEHICLE_CMD_PREFLIGHT_STORAGE:
+		param = (int)(cmd->param3);
+
+		if (param == 1)	{
+			sdlog2_start_log();
+
+		} else if (param == 0)	{
+			sdlog2_stop_log();
+		}
+
+		break;
+
+	default:
+		/* silently ignore */
+		break;
+	}
+}
+
+void handle_status(struct vehicle_status_s *status)
+{
+	if (status->flag_system_armed != flag_system_armed) {
+		flag_system_armed = status->flag_system_armed;
+
+		if (flag_system_armed) {
+			sdlog2_start_log();
+
+		} else {
+			sdlog2_stop_log();
+		}
+	}
+}
diff --git a/src/modules/sdlog2/sdlog2_format.h b/src/modules/sdlog2/sdlog2_format.h
new file mode 100644
index 000000000..59b91d90d
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2_format.h
@@ -0,0 +1,98 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * 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 sdlog2_format.h
+ *
+ * General log format structures and macro.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+/*
+Format characters in the format string for binary log messages
+  b   : int8_t
+  B   : uint8_t
+  h   : int16_t
+  H   : uint16_t
+  i   : int32_t
+  I   : uint32_t
+  f   : float
+  n   : char[4]
+  N   : char[16]
+  Z   : char[64]
+  c   : int16_t * 100
+  C   : uint16_t * 100
+  e   : int32_t * 100
+  E   : uint32_t * 100
+  L   : int32_t latitude/longitude
+  M   : uint8_t flight mode
+
+  q   : int64_t
+  Q   : uint64_t
+ */
+
+#ifndef SDLOG2_FORMAT_H_
+#define SDLOG2_FORMAT_H_
+
+#define LOG_PACKET_HEADER_LEN	   3
+#define LOG_PACKET_HEADER	       uint8_t head1, head2, msg_type;
+#define LOG_PACKET_HEADER_INIT(id) .head1 = HEAD_BYTE1, .head2 = HEAD_BYTE2, .msg_type = id
+
+// once the logging code is all converted we will remove these from
+// this header
+#define HEAD_BYTE1  0xA3    // Decimal 163
+#define HEAD_BYTE2  0x95    // Decimal 149
+
+struct log_format_s {
+	uint8_t type;
+	uint8_t length;		// full packet length including header
+	char name[4];
+	char format[16];
+	char labels[64];
+};
+
+#define LOG_FORMAT(_name, _format, _labels) { \
+		.type = LOG_##_name##_MSG, \
+		.length = sizeof(struct log_##_name##_s) + LOG_PACKET_HEADER_LEN, \
+		.name = #_name, \
+		.format = _format, \
+		.labels = _labels \
+	}
+
+#define LOG_FORMAT_MSG	  0x80
+
+#define LOG_PACKET_SIZE(_name)	LOG_PACKET_HEADER_LEN + sizeof(struct log_##_name##_s)
+
+#endif /* SDLOG2_FORMAT_H_ */
diff --git a/src/modules/sdlog2/sdlog2_messages.h b/src/modules/sdlog2/sdlog2_messages.h
new file mode 100644
index 000000000..40763ee1e
--- /dev/null
+++ b/src/modules/sdlog2/sdlog2_messages.h
@@ -0,0 +1,191 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * 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 sdlog2_messages.h
+ *
+ * Log messages and structures definition.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#ifndef SDLOG2_MESSAGES_H_
+#define SDLOG2_MESSAGES_H_
+
+#include "sdlog2_format.h"
+
+/* define message formats */
+
+#pragma pack(push, 1)
+/* --- TIME - TIME STAMP --- */
+#define LOG_TIME_MSG 1
+struct log_TIME_s {
+	uint64_t t;
+};
+
+/* --- ATT - ATTITUDE --- */
+#define LOG_ATT_MSG 2
+struct log_ATT_s {
+	float roll;
+	float pitch;
+	float yaw;
+};
+
+/* --- ATSP - ATTITUDE SET POINT --- */
+#define LOG_ATSP_MSG 3
+struct log_ATSP_s {
+	float roll_sp;
+	float pitch_sp;
+	float yaw_sp;
+};
+
+/* --- IMU - IMU SENSORS --- */
+#define LOG_IMU_MSG 4
+struct log_IMU_s {
+	float acc_x;
+	float acc_y;
+	float acc_z;
+	float gyro_x;
+	float gyro_y;
+	float gyro_z;
+	float mag_x;
+	float mag_y;
+	float mag_z;
+};
+
+/* --- SENS - OTHER SENSORS --- */
+#define LOG_SENS_MSG 5
+struct log_SENS_s {
+	float baro_pres;
+	float baro_alt;
+	float baro_temp;
+	float diff_pres;
+};
+
+/* --- LPOS - LOCAL POSITION --- */
+#define LOG_LPOS_MSG 6
+struct log_LPOS_s {
+	float x;
+	float y;
+	float z;
+	float vx;
+	float vy;
+	float vz;
+	float hdg;
+	int32_t home_lat;
+	int32_t home_lon;
+	float home_alt;
+};
+
+/* --- LPSP - LOCAL POSITION SETPOINT --- */
+#define LOG_LPSP_MSG 7
+struct log_LPSP_s {
+	float x;
+	float y;
+	float z;
+	float yaw;
+};
+
+/* --- GPS - GPS POSITION --- */
+#define LOG_GPS_MSG 8
+struct log_GPS_s {
+	uint64_t gps_time;
+	uint8_t fix_type;
+	float eph;
+	float epv;
+	int32_t lat;
+	int32_t lon;
+	float alt;
+	float vel_n;
+	float vel_e;
+	float vel_d;
+	float cog;
+};
+
+/* --- ATTC - ATTITUDE CONTROLS (ACTUATOR_0 CONTROLS)--- */
+#define LOG_ATTC_MSG 9
+struct log_ATTC_s {
+	float roll;
+	float pitch;
+	float yaw;
+	float thrust;
+};
+
+/* --- STAT - VEHICLE STATE --- */
+#define LOG_STAT_MSG 10
+struct log_STAT_s {
+	unsigned char state;
+	unsigned char flight_mode;
+	unsigned char manual_control_mode;
+	unsigned char manual_sas_mode;
+	unsigned char armed;
+	float battery_voltage;
+	float battery_current;
+	float battery_remaining;
+	unsigned char battery_warning;
+};
+
+/* --- RC - RC INPUT CHANNELS --- */
+#define LOG_RC_MSG 11
+struct log_RC_s {
+	float channel[8];
+};
+
+/* --- OUT0 - ACTUATOR_0 OUTPUT --- */
+#define LOG_OUT0_MSG 12
+struct log_OUT0_s {
+	float output[8];
+};
+#pragma pack(pop)
+
+/* construct list of all message formats */
+
+static const struct log_format_s log_formats[] = {
+	LOG_FORMAT(TIME, "Q", "StartTime"),
+	LOG_FORMAT(ATT, "fff", "Roll,Pitch,Yaw"),
+	LOG_FORMAT(ATSP, "fff", "RollSP,PitchSP,YawSP"),
+	LOG_FORMAT(IMU, "fffffffff", "AccX,AccY,AccZ,GyroX,GyroY,GyroZ,MagX,MagY,MagZ"),
+	LOG_FORMAT(SENS, "ffff", "BaroPres,BaroAlt,BaroTemp,DiffPres"),
+	LOG_FORMAT(LPOS, "fffffffLLf", "X,Y,Z,VX,VY,VZ,Heading,HomeLat,HomeLon,HomeAlt"),
+	LOG_FORMAT(LPSP, "ffff", "X,Y,Z,Yaw"),
+	LOG_FORMAT(GPS, "QBffLLfffff", "GPSTime,FixType,EPH,EPV,Lat,Lon,Alt,VelN,VelE,VelD,Cog"),
+	LOG_FORMAT(ATTC, "ffff", "Roll,Pitch,Yaw,Thrust"),
+	LOG_FORMAT(STAT, "BBBBBfffB", "State,FlightMode,CtlMode,SASMode,Armed,BatV,BatC,BatRem,BatWarn"),
+	LOG_FORMAT(RC, "ffffffff", "Ch0,Ch1,Ch2,Ch3,Ch4,Ch5,Ch6,Ch7"),
+	LOG_FORMAT(OUT0, "ffffffff", "Out0,Out1,Out2,Out3,Out4,Out5,Out6,Out7"),
+};
+
+static const int log_formats_num = sizeof(log_formats) / sizeof(struct log_format_s);
+
+#endif /* SDLOG2_MESSAGES_H_ */
diff --git a/src/modules/systemlib/geo/geo.c b/src/modules/systemlib/geo/geo.c
index 6746e8ff3..6463e6489 100644
--- a/src/modules/systemlib/geo/geo.c
+++ b/src/modules/systemlib/geo/geo.c
@@ -185,12 +185,11 @@ __EXPORT float get_distance_to_next_waypoint(double lat_now, double lon_now, dou
 	double d_lat = lat_next_rad - lat_now_rad;
 	double d_lon = lon_next_rad - lon_now_rad;
 
-	double a = sin(d_lat / 2.0d) * sin(d_lat / 2.0) + sin(d_lon / 2.0d) * sin(d_lon / 2.0d) * cos(lat_now_rad) * cos(lat_next_rad);
+	double a = sin(d_lat / 2.0d) * sin(d_lat / 2.0d) + sin(d_lon / 2.0d) * sin(d_lon / 2.0d) * cos(lat_now_rad) * cos(lat_next_rad);
 	double c = 2.0d * atan2(sqrt(a), sqrt(1.0d - a));
 
 	const double radius_earth = 6371000.0d;
-
-	return radius_earth * c;
+	return radius_earth * c; 
 }
 
 __EXPORT float get_bearing_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next)
diff --git a/src/modules/systemlib/geo/geo.h b/src/modules/systemlib/geo/geo.h
index 0c0b5c533..84097b49f 100644
--- a/src/modules/systemlib/geo/geo.h
+++ b/src/modules/systemlib/geo/geo.h
@@ -82,8 +82,24 @@ __EXPORT void map_projection_project(double lat, double lon, float *x, float *y)
  */
 __EXPORT void map_projection_reproject(float x, float y, double *lat, double *lon);
 
+/**
+ * Returns the distance to the next waypoint in meters.
+ *
+ * @param lat_now current position in degrees (47.1234567°, not 471234567°)
+ * @param lon_now current position in degrees (8.1234567°, not 81234567°)
+ * @param lat_next next waypoint position in degrees (47.1234567°, not 471234567°)
+ * @param lon_next next waypoint position in degrees (8.1234567°, not 81234567°)
+ */
 __EXPORT float get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);
 
+/**
+ * Returns the bearing to the next waypoint in radians.
+ *
+ * @param lat_now current position in degrees (47.1234567°, not 471234567°)
+ * @param lon_now current position in degrees (8.1234567°, not 81234567°)
+ * @param lat_next next waypoint position in degrees (47.1234567°, not 471234567°)
+ * @param lon_next next waypoint position in degrees (8.1234567°, not 81234567°)
+ */
 __EXPORT float get_bearing_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);
 
 __EXPORT int get_distance_to_line(struct crosstrack_error_s * crosstrack_error, double lat_now, double lon_now, double lat_start, double lon_start, double lat_end, double lon_end);