ardupilot/ArduPlane/ArduPlane.pde

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-

#define THISFIRMWARE "ArduPlane V2.50"
/*
Authors:    Doug Weibel, Jose Julio, Jordi Munoz, Jason Short, Andrew Tridgell, Randy Mackay, Pat Hickey, John Arne Birkeland, Olivier Adler, Amilcar Lucas, Gregory Fletcher
Thanks to:  Chris Anderson, Michael Oborne, Paul Mather, Bill Premerlani, James Cohen, JB from rotorFX, Automatik, Fefenin, Peter Meister, Remzibi, Yury Smirnov, Sandro Benigno, Max Levine, Roberto Navoni, Lorenz Meier, Yury MonZon
Please contribute your ideas!


This firmware is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
*/

////////////////////////////////////////////////////////////////////////////////
// Header includes
////////////////////////////////////////////////////////////////////////////////

// AVR runtime
#include <avr/io.h>
#include <avr/eeprom.h>
#include <avr/pgmspace.h>
#include <math.h>

// Libraries
#include <FastSerial.h>
#include <AP_Common.h>
#include <Arduino_Mega_ISR_Registry.h>
#include <APM_RC.h>         // ArduPilot Mega RC Library
#include <AP_GPS.h>         // ArduPilot GPS library
#include <I2C.h>			// Wayne Truchsess I2C lib
#include <SPI.h>			// Arduino SPI lib
#include <DataFlash.h>      // ArduPilot Mega Flash Memory Library
#include <AP_ADC.h>         // ArduPilot Mega Analog to Digital Converter Library
#include <AP_AnalogSource.h>// ArduPilot Mega polymorphic analog getter
#include <AP_PeriodicProcess.h> // ArduPilot Mega TimerProcess
#include <AP_Baro.h>        // ArduPilot barometer library
#include <AP_Compass.h>     // ArduPilot Mega Magnetometer Library
#include <AP_Math.h>        // ArduPilot Mega Vector/Matrix math Library
#include <AP_InertialSensor.h> // Inertial Sensor (uncalibrated IMU) Library
#include <AP_IMU.h>         // ArduPilot Mega IMU Library
#include <AP_AHRS.h>         // ArduPilot Mega DCM Library
#include <PID.h>            // PID library
#include <RC_Channel.h>     // RC Channel Library
#include <AP_RangeFinder.h>	// Range finder library
#include <Filter.h>			// Filter library
#include <ModeFilter.h>		// Mode Filter from Filter library
#include <LowPassFilter.h>	// LowPassFilter class (inherits from Filter class)
#include <AP_Relay.h>       // APM relay
#include <AP_Camera.h>		// Photo or video camera
#include <AP_Airspeed.h>
#include <memcheck.h>

// Configuration
#include "config.h"

#include <GCS_MAVLink.h>    // MAVLink GCS definitions

#include <AP_Mount.h>		// Camera/Antenna mount

// Local modules
#include "defines.h"
#include "Parameters.h"
#include "GCS.h"

#include <AP_Declination.h> // ArduPilot Mega Declination Helper Library

////////////////////////////////////////////////////////////////////////////////
// Serial ports
////////////////////////////////////////////////////////////////////////////////
//
// Note that FastSerial port buffers are allocated at ::begin time,
// so there is not much of a penalty to defining ports that we don't
// use.
//
FastSerialPort0(Serial);        // FTDI/console
FastSerialPort1(Serial1);       // GPS port
#if TELEMETRY_UART2 == ENABLED
 // solder bridge set to enable UART2 instead of USB MUX
 FastSerialPort2(Serial3);
#else
 FastSerialPort3(Serial3);       // Telemetry port for APM1
#endif

// this sets up the parameter table, and sets the default values. This
// must be the first AP_Param variable declared to ensure its
// constructor runs before the constructors of the other AP_Param
// variables
AP_Param param_loader(var_info, WP_START_BYTE);


////////////////////////////////////////////////////////////////////////////////
// ISR Registry
////////////////////////////////////////////////////////////////////////////////
Arduino_Mega_ISR_Registry isr_registry;


////////////////////////////////////////////////////////////////////////////////
// APM_RC_Class Instance
////////////////////////////////////////////////////////////////////////////////
#if CONFIG_APM_HARDWARE == APM_HARDWARE_APM2
    APM_RC_APM2 APM_RC;
#else
    APM_RC_APM1 APM_RC;
#endif

////////////////////////////////////////////////////////////////////////////////
// Dataflash
////////////////////////////////////////////////////////////////////////////////
#if CONFIG_APM_HARDWARE == APM_HARDWARE_APM2
    DataFlash_APM2 DataFlash;
#else
    DataFlash_APM1   DataFlash;
#endif


////////////////////////////////////////////////////////////////////////////////
// Parameters
////////////////////////////////////////////////////////////////////////////////
//
// Global parameters are all contained within the 'g' class.
//
static Parameters      g;


////////////////////////////////////////////////////////////////////////////////
// prototypes
static void update_events(void);


////////////////////////////////////////////////////////////////////////////////
// Sensors
////////////////////////////////////////////////////////////////////////////////
//
// There are three basic options related to flight sensor selection.
//
// - Normal flight mode.  Real sensors are used.
// - HIL Attitude mode.  Most sensors are disabled, as the HIL
//   protocol supplies attitude information directly.
// - HIL Sensors mode.  Synthetic sensors are configured that
//   supply data from the simulation.
//

// All GPS access should be through this pointer.
static GPS         *g_gps;

// flight modes convenience array
static AP_Int8		*flight_modes = &g.flight_mode1;

#if HIL_MODE == HIL_MODE_DISABLED

// real sensors
#if CONFIG_ADC == ENABLED
static AP_ADC_ADS7844          adc;
#endif

#ifdef DESKTOP_BUILD
AP_Baro_BMP085_HIL      barometer;
AP_Compass_HIL          compass;
#include <SITL.h>
SITL					sitl;
#else

#if CONFIG_BARO == AP_BARO_BMP085
# if CONFIG_APM_HARDWARE == APM_HARDWARE_APM2
static AP_Baro_BMP085          barometer(true);
# else
static AP_Baro_BMP085          barometer(false);
# endif
#elif CONFIG_BARO == AP_BARO_MS5611
static AP_Baro_MS5611          barometer;
#endif

static AP_Compass_HMC5843      compass;
#endif

// real GPS selection
#if   GPS_PROTOCOL == GPS_PROTOCOL_AUTO
AP_GPS_Auto     g_gps_driver(&Serial1, &g_gps);

#elif GPS_PROTOCOL == GPS_PROTOCOL_NMEA
AP_GPS_NMEA     g_gps_driver(&Serial1);

#elif GPS_PROTOCOL == GPS_PROTOCOL_SIRF
AP_GPS_SIRF     g_gps_driver(&Serial1);

#elif GPS_PROTOCOL == GPS_PROTOCOL_UBLOX
AP_GPS_UBLOX    g_gps_driver(&Serial1);

#elif GPS_PROTOCOL == GPS_PROTOCOL_MTK
AP_GPS_MTK      g_gps_driver(&Serial1);

#elif GPS_PROTOCOL == GPS_PROTOCOL_MTK16
AP_GPS_MTK16    g_gps_driver(&Serial1);

#elif GPS_PROTOCOL == GPS_PROTOCOL_NONE
AP_GPS_None     g_gps_driver(NULL);

#else
 #error Unrecognised GPS_PROTOCOL setting.
#endif // GPS PROTOCOL

# if CONFIG_IMU_TYPE == CONFIG_IMU_MPU6000
  AP_InertialSensor_MPU6000 ins( CONFIG_MPU6000_CHIP_SELECT_PIN );
# else
  AP_InertialSensor_Oilpan ins( &adc );
#endif // CONFIG_IMU_TYPE
AP_IMU_INS imu( &ins );

#if QUATERNION_ENABLE == ENABLED
  AP_AHRS_Quaternion ahrs(&imu, g_gps);
#else
 #if DMP_ENABLED == ENABLED && CONFIG_APM_HARDWARE == APM_HARDWARE_APM2
  AP_AHRS_MPU6000 ahrs(&imu, g_gps, &ins);		// only works with APM2
 #else
  AP_AHRS_DCM ahrs(&imu, g_gps);
 #endif
#endif

#elif HIL_MODE == HIL_MODE_SENSORS
// sensor emulators
AP_ADC_HIL              adc;
AP_Baro_BMP085_HIL      barometer;
AP_Compass_HIL          compass;
AP_GPS_HIL              g_gps_driver(NULL);
AP_InertialSensor_Oilpan ins( &adc );
AP_IMU_Shim imu;
AP_AHRS_DCM  ahrs(&imu, g_gps);

#elif HIL_MODE == HIL_MODE_ATTITUDE
AP_ADC_HIL              adc;
AP_IMU_Shim             imu; // never used
AP_AHRS_HIL             ahrs(&imu, g_gps);
AP_GPS_HIL              g_gps_driver(NULL);
AP_Compass_HIL          compass; // never used
AP_Baro_BMP085_HIL      barometer;
#ifdef DESKTOP_BUILD
#include <SITL.h>
SITL					sitl;
AP_InertialSensor_Oilpan ins( &adc );
#endif

#else
 #error Unrecognised HIL_MODE setting.
#endif // HIL MODE

// we always have a timer scheduler
AP_TimerProcess timer_scheduler;


////////////////////////////////////////////////////////////////////////////////
// GCS selection
////////////////////////////////////////////////////////////////////////////////
//
GCS_MAVLINK	gcs0;
GCS_MAVLINK	gcs3;

////////////////////////////////////////////////////////////////////////////////
// PITOT selection
////////////////////////////////////////////////////////////////////////////////
//
ModeFilterInt16_Size5 sonar_mode_filter(2);

#if CONFIG_PITOT_SOURCE == PITOT_SOURCE_ADC
AP_AnalogSource_ADC pitot_analog_source( &adc,
                        CONFIG_PITOT_SOURCE_ADC_CHANNEL, 1.0);
#elif CONFIG_PITOT_SOURCE == PITOT_SOURCE_ANALOG_PIN
AP_AnalogSource_Arduino pitot_analog_source(CONFIG_PITOT_SOURCE_ANALOG_PIN, 4.0);
#endif

#if SONAR_TYPE == MAX_SONAR_XL
	AP_RangeFinder_MaxsonarXL sonar(&pitot_analog_source, &sonar_mode_filter);
#elif SONAR_TYPE == MAX_SONAR_LV
	// XXX honestly I think these output the same values
	// If someone knows, can they confirm it?
	AP_RangeFinder_MaxsonarXL sonar(&pitot_analog_source, &sonar_mode_filter);
#endif

AP_Relay relay;



////////////////////////////////////////////////////////////////////////////////
// Global variables
////////////////////////////////////////////////////////////////////////////////

// APM2 only
#if USB_MUX_PIN > 0
static bool usb_connected;
#endif

static const char *comma = ",";

static const char* flight_mode_strings[] = {
	"Manual",
	"Circle",
	"Stabilize",
	"",
	"",
	"FBW_A",
	"FBW_B",
	"",
	"",
	"",
	"Auto",
	"RTL",
	"Loiter",
	"Takeoff",
	"Land"};


/* Radio values
		Channel assignments
			1   Ailerons (rudder if no ailerons)
			2   Elevator
			3   Throttle
			4   Rudder (if we have ailerons)
			5   Aux5
			6   Aux6
			7   Aux7
			8   Aux8/Mode
		Each Aux channel can be configured to have any of the available auxiliary functions assigned to it.
		See libraries/RC_Channel/RC_Channel_aux.h for more information
*/

////////////////////////////////////////////////////////////////////////////////
// Radio
////////////////////////////////////////////////////////////////////////////////
// This is the state of the flight control system
// There are multiple states defined such as MANUAL, FBW-A, AUTO
byte    control_mode        = INITIALISING;
// Used to maintain the state of the previous control switch position
// This is set to -1 when we need to re-read the switch
byte 	oldSwitchPosition;
// This is used to enable the inverted flight feature
bool    inverted_flight     = false;
// These are trim values used for elevon control
// For elevons radio_in[CH_ROLL] and radio_in[CH_PITCH] are equivalent aileron and elevator, not left and right elevon
static uint16_t elevon1_trim  = 1500;
static uint16_t elevon2_trim  = 1500;
// These are used in the calculation of elevon1_trim and elevon2_trim
static uint16_t ch1_temp      = 1500;
static uint16_t ch2_temp  	= 1500;
// These are values received from the GCS if the user is using GCS joystick
// control and are substituted for the values coming from the RC radio
static int16_t rc_override[8] = {0,0,0,0,0,0,0,0};
// A flag if GCS joystick control is in use
static bool rc_override_active = false;

////////////////////////////////////////////////////////////////////////////////
// Failsafe
////////////////////////////////////////////////////////////////////////////////
// A tracking variable for type of failsafe active
// Used for failsafe based on loss of RC signal or GCS signal
static int16_t 	failsafe;
// Used to track if the value on channel 3 (throtttle) has fallen below the failsafe threshold
// RC receiver should be set up to output a low throttle value when signal is lost
static bool 	ch3_failsafe;
// A timer used to help recovery from unusual attitudes.  If we enter an unusual attitude
// while in autonomous flight this variable is used  to hold roll at 0 for a recovery period
static byte    crash_timer;
// A timer used to track how long since we have received the last GCS heartbeat or rc override message
static uint32_t rc_override_fs_timer = 0;
// A timer used to track how long we have been in a "short failsafe" condition due to loss of RC signal
static uint32_t ch3_failsafe_timer = 0;

////////////////////////////////////////////////////////////////////////////////
// LED output
////////////////////////////////////////////////////////////////////////////////
// state of the GPS light (on/off)
static bool GPS_light;

////////////////////////////////////////////////////////////////////////////////
// GPS variables
////////////////////////////////////////////////////////////////////////////////
// This is used to scale GPS values for EEPROM storage
// 10^7 times Decimal GPS means 1 == 1cm
// This approximation makes calculations integer and it's easy to read
static const 	float t7			= 10000000.0;
// We use atan2 and other trig techniques to calaculate angles
// A counter used to count down valid gps fixes to allow the gps estimate to settle
// before recording our home position (and executing a ground start if we booted with an air start)
static byte 	ground_start_count	= 5;
// Used to compute a speed estimate from the first valid gps fixes to decide if we are
// on the ground or in the air.  Used to decide if a ground start is appropriate if we
// booted with an air start.
static int16_t     ground_start_avg;
// Tracks if GPS is enabled based on statup routine
// If we do not detect GPS at startup, we stop trying and assume GPS is not connected
static bool	GPS_enabled 	= false;

// true if we have a position estimate from AHRS
static bool have_position;

////////////////////////////////////////////////////////////////////////////////
// Location & Navigation
////////////////////////////////////////////////////////////////////////////////
// Constants
const	float radius_of_earth 	= 6378100;	// meters
const	float gravity 			= 9.81;		// meters/ sec^2

// This is the currently calculated direction to fly.
// deg * 100 : 0 to 360
static int32_t	nav_bearing_cd;

// This is the direction to the next waypoint or loiter center
// deg * 100 : 0 to 360
static int32_t	target_bearing_cd;

//This is the direction from the last waypoint to the next waypoint
// deg * 100 : 0 to 360
static int32_t	crosstrack_bearing_cd;

// Direction held during phases of takeoff and landing
// deg * 100 dir of plane,  A value of -1 indicates the course has not been set/is not in use
static int32_t    hold_course       	 	= -1;		// deg * 100 dir of plane

// There may be two active commands in Auto mode.
// This indicates the active navigation command by index number
static byte	nav_command_index;
// This indicates the active non-navigation command by index number
static byte	non_nav_command_index;
// This is the command type (eg navigate to waypoint) of the active navigation command
static byte	nav_command_ID		= NO_COMMAND;
static byte	non_nav_command_ID	= NO_COMMAND;

////////////////////////////////////////////////////////////////////////////////
// Airspeed
////////////////////////////////////////////////////////////////////////////////
// The calculated airspeed to use in FBW-B.  Also used in higher modes for insuring min ground speed is met.
// Also used for flap deployment criteria.  Centimeters per second.
static int32_t		target_airspeed_cm;

// The difference between current and desired airspeed.  Used in the pitch controller.  Centimeters per second.
static float	airspeed_error_cm;

// The calculated total energy error (kinetic (altitude) plus potential (airspeed)).
// Used by the throttle controller
static int32_t 	energy_error;

// kinetic portion of energy error (m^2/s^2)
static int32_t		airspeed_energy_error;

// An amount that the airspeed should be increased in auto modes based on the user positioning the
// throttle stick in the top half of the range.  Centimeters per second.
static int16_t		airspeed_nudge_cm;

// Similar to airspeed_nudge, but used when no airspeed sensor.
// 0-(throttle_max - throttle_cruise) : throttle nudge in Auto mode using top 1/2 of throttle stick travel
static int16_t     throttle_nudge = 0;

////////////////////////////////////////////////////////////////////////////////
// Ground speed
////////////////////////////////////////////////////////////////////////////////
// The amount current ground speed is below min ground speed.  Centimeters per second
static int32_t		groundspeed_undershoot = 0;

////////////////////////////////////////////////////////////////////////////////
// Location Errors
////////////////////////////////////////////////////////////////////////////////
// Difference between current bearing and desired bearing.  Hundredths of a degree
static int32_t	bearing_error_cd;

// Difference between current altitude and desired altitude.  Centimeters
static int32_t	altitude_error_cm;

// Distance perpandicular to the course line that we are off trackline.  Meters
static float	crosstrack_error;

////////////////////////////////////////////////////////////////////////////////
// Battery Sensors
////////////////////////////////////////////////////////////////////////////////
// Battery pack 1 voltage.  Initialized above the low voltage threshold to pre-load the filter and prevent low voltage events at startup.
static float 	battery_voltage1 	= LOW_VOLTAGE * 1.05;
// Battery pack 1 instantaneous currrent draw.  Amperes
static float	current_amps1;
// Totalized current (Amp-hours) from battery 1
static float	current_total1;

// To Do - Add support for second battery pack
//static float 	battery_voltage2 	= LOW_VOLTAGE * 1.05;		// Battery 2 Voltage, initialized above threshold for filter
//static float	current_amps2;									// Current (Amperes) draw from battery 2
//static float	current_total2;									// Totalized current (Amp-hours) from battery 2

////////////////////////////////////////////////////////////////////////////////
// Airspeed Sensors
////////////////////////////////////////////////////////////////////////////////
AP_Airspeed airspeed(&pitot_analog_source);

////////////////////////////////////////////////////////////////////////////////
// Altitude Sensor variables
////////////////////////////////////////////////////////////////////////////////
// Altitude from the sonar sensor.  Meters.  Not yet implemented.
static int16_t		sonar_alt;

////////////////////////////////////////////////////////////////////////////////
// flight mode specific
////////////////////////////////////////////////////////////////////////////////
// Flag for using gps ground course instead of IMU yaw.  Set false when takeoff command in process.
static bool takeoff_complete    = true;
// Flag to indicate if we have landed.
//Set land_complete if we are within 2 seconds distance or within 3 meters altitude of touchdown
static bool	land_complete;
// Altitude threshold to complete a takeoff command in autonomous modes.  Centimeters
static int32_t	takeoff_altitude;

// Minimum pitch to hold during takeoff command execution.  Hundredths of a degree
static int16_t			takeoff_pitch_cd;

////////////////////////////////////////////////////////////////////////////////
// Loiter management
////////////////////////////////////////////////////////////////////////////////
// Previous target bearing.  Used to calculate loiter rotations.  Hundredths of a degree
static int32_t 	old_target_bearing_cd;

// Total desired rotation in a loiter.  Used for Loiter Turns commands.  Degrees
static int32_t		loiter_total;

// The amount in degrees we have turned since recording old_target_bearing
static int16_t 	loiter_delta;

// Total rotation in a loiter.  Used for Loiter Turns commands and to check for missed waypoints.  Degrees
static int32_t		loiter_sum;

// The amount of time we have been in a Loiter.  Used for the Loiter Time command.  Milliseconds.
static uint32_t 	loiter_time_ms;

// The amount of time we should stay in a loiter for the Loiter Time command.  Milliseconds.
static uint32_t 	loiter_time_max_ms;

////////////////////////////////////////////////////////////////////////////////
// Navigation control variables
////////////////////////////////////////////////////////////////////////////////
// The instantaneous desired bank angle.  Hundredths of a degree
static int32_t	nav_roll_cd;

// The instantaneous desired pitch angle.  Hundredths of a degree
static int32_t	nav_pitch_cd;

////////////////////////////////////////////////////////////////////////////////
// Waypoint distances
////////////////////////////////////////////////////////////////////////////////
// Distance between plane and next waypoint.  Meters
// is not static because AP_Camera uses it
int32_t	wp_distance;

// Distance between previous and next waypoint.  Meters
static int32_t	wp_totalDistance;

////////////////////////////////////////////////////////////////////////////////
// repeating event control
////////////////////////////////////////////////////////////////////////////////
// Flag indicating current event type
static byte 		event_id;

// when the event was started in ms
static int32_t 		event_timer_ms;

// how long to delay the next firing of event in millis
static uint16_t 	event_delay_ms;

// how many times to cycle : -1 (or -2) = forever, 2 = do one cycle, 4 = do two cycles
static int16_t 		event_repeat = 0;
// per command value, such as PWM for servos
static int16_t 		event_value;
// the value used to cycle events (alternate value to event_value)
static int16_t 		event_undo_value;

////////////////////////////////////////////////////////////////////////////////
// Conditional command
////////////////////////////////////////////////////////////////////////////////
// A value used in condition commands (eg delay, change alt, etc.)
// For example in a change altitude command, it is the altitude to change to.
static int32_t 	condition_value;
// A starting value used to check the status of a conditional command.
// For example in a delay command the condition_start records that start time for the delay
static uint32_t condition_start;
// A value used in condition commands.  For example the rate at which to change altitude.
static int16_t 	condition_rate;

////////////////////////////////////////////////////////////////////////////////
// 3D Location vectors
// Location structure defined in AP_Common
////////////////////////////////////////////////////////////////////////////////
// The home location used for RTL.  The location is set when we first get stable GPS lock
static struct 	Location home;
// Flag for if we have g_gps lock and have set the home location
static bool	home_is_set;
// The location of the previous waypoint.  Used for track following and altitude ramp calculations
static struct 	Location prev_WP;
// The plane's current location
static struct 	Location current_loc;
// The location of the current/active waypoint.  Used for altitude ramp, track following and loiter calculations.
static struct 	Location next_WP;
// The location of the active waypoint in Guided mode.
static struct  	Location guided_WP;
// The location structure information from the Nav command being processed
static struct 	Location next_nav_command;
// The location structure information from the Non-Nav command being processed
static struct 	Location next_nonnav_command;

////////////////////////////////////////////////////////////////////////////////
// Altitude / Climb rate control
////////////////////////////////////////////////////////////////////////////////
// The current desired altitude.  Altitude is linearly ramped between waypoints.  Centimeters
static int32_t 	target_altitude_cm;
// Altitude difference between previous and current waypoint.  Centimeters
static int32_t 	offset_altitude_cm;

////////////////////////////////////////////////////////////////////////////////
// IMU variables
////////////////////////////////////////////////////////////////////////////////
// The main loop execution time.  Seconds
//This is the time between calls to the DCM algorithm and is the Integration time for the gyros.
static float G_Dt						= 0.02;

////////////////////////////////////////////////////////////////////////////////
// Performance monitoring
////////////////////////////////////////////////////////////////////////////////
// Timer used to accrue data and trigger recording of the performanc monitoring log message
static int32_t 	perf_mon_timer;
// The maximum main loop execution time recorded in the current performance monitoring interval
static int 	G_Dt_max = 0;
// The number of gps fixes recorded in the current performance monitoring interval
static int16_t 	gps_fix_count = 0;
// A variable used by developers to track performanc metrics.
// Currently used to record the number of GCS heartbeat messages received
static int16_t		pmTest1 = 0;


////////////////////////////////////////////////////////////////////////////////
// System Timers
////////////////////////////////////////////////////////////////////////////////
// Time in miliseconds of start of main control loop.  Milliseconds
static uint32_t 	fast_loopTimer_ms;

// Time Stamp when fast loop was complete.  Milliseconds
static uint32_t 	fast_loopTimeStamp_ms;

// Number of milliseconds used in last main loop cycle
static uint8_t 		delta_ms_fast_loop;

// Counter of main loop executions.  Used for performance monitoring and failsafe processing
static uint16_t			mainLoop_count;

// Time in miliseconds of start of medium control loop.  Milliseconds
static uint32_t 	medium_loopTimer_ms;

// Counters for branching from main control loop to slower loops
static byte 			medium_loopCounter;
// Number of milliseconds used in last medium loop cycle
static uint8_t			delta_ms_medium_loop;

// Counters for branching from medium control loop to slower loops
static byte 			slow_loopCounter;
// Counter to trigger execution of very low rate processes
static byte 			superslow_loopCounter;
// Counter to trigger execution of 1 Hz processes
static byte				counter_one_herz;

// % MCU cycles used
static float 			load;


// Camera/Antenna mount tracking and stabilisation stuff
// --------------------------------------
#if MOUNT == ENABLED
// current_loc uses the baro/gps soloution for altitude rather than gps only.
// mabe one could use current_loc for lat/lon too and eliminate g_gps alltogether?
AP_Mount camera_mount(&current_loc, g_gps, &ahrs, 0);
#endif

#if MOUNT2 == ENABLED
// current_loc uses the baro/gps soloution for altitude rather than gps only.
// mabe one could use current_loc for lat/lon too and eliminate g_gps alltogether?
AP_Mount camera_mount2(&current_loc, g_gps, &ahrs, 1);
#endif

#if CAMERA == ENABLED
//pinMode(camtrig, OUTPUT);			// these are free pins PE3(5), PH3(15), PH6(18), PB4(23), PB5(24), PL1(36), PL3(38), PA6(72), PA7(71), PK0(89), PK1(88), PK2(87), PK3(86), PK4(83), PK5(84), PK6(83), PK7(82)
#endif

////////////////////////////////////////////////////////////////////////////////
// Top-level logic
////////////////////////////////////////////////////////////////////////////////

void setup() {
	memcheck_init();
	init_ardupilot();
}

void loop()
{
	// We want this to execute at 50Hz if possible
	// -------------------------------------------
	if (millis() - fast_loopTimer_ms > 19) {
		delta_ms_fast_loop	= millis() - fast_loopTimer_ms;
		load                = (float)(fast_loopTimeStamp_ms - fast_loopTimer_ms)/delta_ms_fast_loop;
		G_Dt                = (float)delta_ms_fast_loop / 1000.f;
		fast_loopTimer_ms   = millis();

		mainLoop_count++;

		// Execute the fast loop
		// ---------------------
		fast_loop();

		// Execute the medium loop
		// -----------------------
		medium_loop();

		counter_one_herz++;
		if(counter_one_herz == 50){
			one_second_loop();
			counter_one_herz = 0;
		}

		if (millis() - perf_mon_timer > 20000) {
			if (mainLoop_count != 0) {
				if (g.log_bitmask & MASK_LOG_PM)
					#if HIL_MODE != HIL_MODE_ATTITUDE
					Log_Write_Performance();
					#endif

				resetPerfData();
			}
		}

		fast_loopTimeStamp_ms = millis();
	}
}

// Main loop 50Hz
static void fast_loop()
{
	// This is the fast loop - we want it to execute at 50Hz if possible
	// -----------------------------------------------------------------
	if (delta_ms_fast_loop > G_Dt_max)
		G_Dt_max = delta_ms_fast_loop;

	// Read radio
	// ----------
	read_radio();

    // try to send any deferred messages if the serial port now has
    // some space available
    gcs_send_message(MSG_RETRY_DEFERRED);

	// check for loss of control signal failsafe condition
	// ------------------------------------
	check_short_failsafe();

	// Read Airspeed
	// -------------
	if (airspeed.enabled()) {
#if HIL_MODE != HIL_MODE_ATTITUDE
		read_airspeed();
#endif
	}

	#if HIL_MODE == HIL_MODE_SENSORS
		// update hil before AHRS update
		gcs_update();
	#endif

    ahrs.update();

	// uses the yaw from the DCM to give more accurate turns
	calc_bearing_error();

	# if HIL_MODE == HIL_MODE_DISABLED
		if (g.log_bitmask & MASK_LOG_ATTITUDE_FAST)
			Log_Write_Attitude(ahrs.roll_sensor, ahrs.pitch_sensor, ahrs.yaw_sensor);

		if (g.log_bitmask & MASK_LOG_RAW)
			Log_Write_Raw();
	#endif

	// inertial navigation
	// ------------------
	#if INERTIAL_NAVIGATION == ENABLED
		// TODO: implement inertial nav function
		inertialNavigation();
	#endif

	// custom code/exceptions for flight modes
	// ---------------------------------------
	update_current_flight_mode();

	// apply desired roll, pitch and yaw to the plane
	// ----------------------------------------------
	if (control_mode > MANUAL)
		stabilize();

	// write out the servo PWM values
	// ------------------------------
	set_servos();

    gcs_update();
    gcs_data_stream_send();
}

static void medium_loop()
{
#if MOUNT == ENABLED
	camera_mount.update_mount_position();
#endif

#if MOUNT2 == ENABLED
	camera_mount2.update_mount_position();
#endif

#if CAMERA == ENABLED
	g.camera.trigger_pic_cleanup();
#endif

	// This is the start of the medium (10 Hz) loop pieces
	// -----------------------------------------
	switch(medium_loopCounter) {

		// This case deals with the GPS
		//-------------------------------
		case 0:
			medium_loopCounter++;
			if(GPS_enabled){
                update_GPS();
                calc_gndspeed_undershoot();
            }

			#if HIL_MODE != HIL_MODE_ATTITUDE
            if (g.compass_enabled && compass.read()) {
                ahrs.set_compass(&compass);
                compass.null_offsets();
            } else {
                ahrs.set_compass(NULL);
            }
			#endif
/*{
Serial.print(ahrs.roll_sensor, DEC);	Serial.printf_P(PSTR("\t"));
Serial.print(ahrs.pitch_sensor, DEC);	Serial.printf_P(PSTR("\t"));
Serial.print(ahrs.yaw_sensor, DEC);	Serial.printf_P(PSTR("\t"));
Vector3f tempaccel = imu.get_accel();
Serial.print(tempaccel.x, DEC);	Serial.printf_P(PSTR("\t"));
Serial.print(tempaccel.y, DEC);	Serial.printf_P(PSTR("\t"));
Serial.println(tempaccel.z, DEC);
}*/

			break;

		// This case performs some navigation computations
		//------------------------------------------------
		case 1:
			medium_loopCounter++;

			// Read 6-position switch on radio
			// -------------------------------
			read_control_switch();

            // calculate the plane's desired bearing
            // -------------------------------------
            navigate();

			break;

		// command processing
		//------------------------------
		case 2:
			medium_loopCounter++;

			// Read altitude from sensors
			// ------------------
			update_alt();
			if(g.sonar_enabled) sonar_alt = sonar.read();

			// altitude smoothing
			// ------------------
			if (control_mode != FLY_BY_WIRE_B)
				calc_altitude_error();

			// perform next command
			// --------------------
			update_commands();
			break;

		// This case deals with sending high rate telemetry
		//-------------------------------------------------
		case 3:
			medium_loopCounter++;

			#if HIL_MODE != HIL_MODE_ATTITUDE
				if ((g.log_bitmask & MASK_LOG_ATTITUDE_MED) && !(g.log_bitmask & MASK_LOG_ATTITUDE_FAST))
					Log_Write_Attitude(ahrs.roll_sensor, ahrs.pitch_sensor, ahrs.yaw_sensor);

				if (g.log_bitmask & MASK_LOG_CTUN)
					Log_Write_Control_Tuning();
			#endif

			if (g.log_bitmask & MASK_LOG_NTUN)
				Log_Write_Nav_Tuning();

			if (g.log_bitmask & MASK_LOG_GPS)
				Log_Write_GPS(g_gps->time, current_loc.lat, current_loc.lng, g_gps->altitude, current_loc.alt, (long) g_gps->ground_speed, g_gps->ground_course, g_gps->fix, g_gps->num_sats);
			break;

		// This case controls the slow loop
		//---------------------------------
		case 4:
			medium_loopCounter = 0;
			delta_ms_medium_loop	= millis() - medium_loopTimer_ms;
			medium_loopTimer_ms    	= millis();

			if (g.battery_monitoring != 0){
				read_battery();
			}

			slow_loop();
			break;
	}
}

static void slow_loop()
{
	// This is the slow (3 1/3 Hz) loop pieces
	//----------------------------------------
	switch (slow_loopCounter){
		case 0:
			slow_loopCounter++;
			check_long_failsafe();
			superslow_loopCounter++;
			if(superslow_loopCounter >=200) {				//	200 = Execute every minute
				#if HIL_MODE != HIL_MODE_ATTITUDE
					if(g.compass_enabled) {
						compass.save_offsets();
					}
				#endif

				superslow_loopCounter = 0;
			}
			break;

		case 1:
			slow_loopCounter++;

#if CONFIG_APM_HARDWARE == APM_HARDWARE_APM1
			update_aux_servo_function(&g.rc_5, &g.rc_6, &g.rc_7, &g.rc_8);
#else
			update_aux_servo_function(&g.rc_5, &g.rc_6, &g.rc_7, &g.rc_8, &g.rc_9, &g.rc_10, &g.rc_11);
#endif
			enable_aux_servos();

#if MOUNT == ENABLED
			camera_mount.update_mount_type();
#endif
#if MOUNT2 == ENABLED
			camera_mount2.update_mount_type();
#endif
			break;

		case 2:
			slow_loopCounter = 0;
			update_events();

            mavlink_system.sysid = g.sysid_this_mav;		// This is just an ugly hack to keep mavlink_system.sysid sync'd with our parameter

#if USB_MUX_PIN > 0
            check_usb_mux();
#endif

			break;
	}
}

static void one_second_loop()
{
	if (g.log_bitmask & MASK_LOG_CUR)
		Log_Write_Current();

	// send a heartbeat
	gcs_send_message(MSG_HEARTBEAT);
}

static void update_GPS(void)
{
	g_gps->update();
	update_GPS_light();

    // get position from AHRS
    have_position = ahrs.get_position(&current_loc);

	if (g_gps->new_data && g_gps->fix) {
        g_gps->new_data = false;

		// for performance
		// ---------------
		gps_fix_count++;

		if(ground_start_count > 1){
			ground_start_count--;
			ground_start_avg += g_gps->ground_speed;

		} else if (ground_start_count == 1) {
			// We countdown N number of good GPS fixes
			// so that the altitude is more accurate
			// -------------------------------------
			if (current_loc.lat == 0) {
				ground_start_count = 5;

			} else {
				if(ENABLE_AIR_START == 1 && (ground_start_avg / 5) < SPEEDFILT){
					startup_ground();

					if (g.log_bitmask & MASK_LOG_CMD)
						Log_Write_Startup(TYPE_GROUNDSTART_MSG);

					init_home();
				} else if (ENABLE_AIR_START == 0) {
					init_home();
				}

				if (g.compass_enabled) {
					// Set compass declination automatically
					compass.set_initial_location(g_gps->latitude, g_gps->longitude);
				}
				ground_start_count = 0;
			}
		}

        // see if we've breached the geo-fence
        geofence_check(false);
	}
}

static void update_current_flight_mode(void)
{
	if(control_mode == AUTO){
		crash_checker();

		switch(nav_command_ID){
			case MAV_CMD_NAV_TAKEOFF:
				if (hold_course != -1) {
					calc_nav_roll();
				} else {
					nav_roll_cd = 0;
				}

				if(airspeed.use()) {
					calc_nav_pitch();
					if (nav_pitch_cd < takeoff_pitch_cd)
						nav_pitch_cd = takeoff_pitch_cd;
				} else {
					nav_pitch_cd = (float)g_gps->ground_speed / (float)g.airspeed_cruise_cm * (float)takeoff_pitch_cd * 0.5;
					nav_pitch_cd = constrain(nav_pitch_cd, 500, takeoff_pitch_cd);
				}

				g.channel_throttle.servo_out = g.throttle_max; //TODO: Replace with THROTTLE_TAKEOFF or other method of controlling throttle
														//  What is the case for doing something else?  Why wouldn't you want max throttle for TO?
				// ******************************

				break;

			case MAV_CMD_NAV_LAND:
				calc_nav_roll();

				if (airspeed.use()) {
					calc_nav_pitch();
					calc_throttle();
				}else{
					calc_nav_pitch();               // calculate nav_pitch just to use for calc_throttle
					calc_throttle();                // throttle based on altitude error
					nav_pitch_cd = g.land_pitch_cd; // pitch held constant
				}

				if (land_complete) {
                    // we are in the final stage of a landing - force
                    // zero throttle
					g.channel_throttle.servo_out = 0;
				}
				break;

			default:
                // we are doing normal AUTO flight, the special cases
                // are for takeoff and landing
				hold_course = -1;
				calc_nav_roll();
				calc_nav_pitch();
				calc_throttle();
				break;
		}
	}else{
        // hold_course is only used in takeoff and landing
        hold_course = -1;

		switch(control_mode){
			case RTL:
			case LOITER:
			case GUIDED:
				crash_checker();
				calc_nav_roll();
				calc_nav_pitch();
				calc_throttle();
				break;

			case FLY_BY_WIRE_A:
				// set nav_roll and nav_pitch using sticks
				nav_roll_cd  = g.channel_roll.norm_input() * g.roll_limit_cd;
				nav_pitch_cd = g.channel_pitch.norm_input() * (-1) * g.pitch_limit_min_cd;
				// We use pitch_min above because it is usually greater magnitude then pitch_max.  -1 is to compensate for its sign.
				nav_pitch_cd = constrain(nav_pitch_cd, -3000, 3000);	// trying to give more pitch authority
				if (inverted_flight) {
                    nav_pitch_cd = -nav_pitch_cd;
                }
				break;

			case FLY_BY_WIRE_B:
				// Substitute stick inputs for Navigation control output
				// We use g.pitch_limit_min because its magnitude is
				// normally greater than g.pitch_limit_max

                // Thanks to Yury MonZon for the altitude limit code!

				nav_roll_cd = g.channel_roll.norm_input() * g.roll_limit_cd;
				altitude_error_cm = g.channel_pitch.norm_input() * g.pitch_limit_min_cd;

				if ((current_loc.alt >= home.alt+g.FBWB_min_altitude_cm) || (g.FBWB_min_altitude_cm == 0)) {
	 				altitude_error_cm = g.channel_pitch.norm_input() * g.pitch_limit_min_cd;
				} else {
					if (g.channel_pitch.norm_input()<0) {
						altitude_error_cm =( (home.alt + g.FBWB_min_altitude_cm) - current_loc.alt) + g.channel_pitch.norm_input() * g.pitch_limit_min_cd;
					} else {
                        altitude_error_cm =( (home.alt + g.FBWB_min_altitude_cm) - current_loc.alt);
                    }
				}
				calc_throttle();
				calc_nav_pitch();
				break;

			case STABILIZE:
				nav_roll_cd        = 0;
				nav_pitch_cd       = 0;
				// throttle is passthrough
				break;

			case CIRCLE:
				// we have no GPS installed and have lost radio contact
				// or we just want to fly around in a gentle circle w/o GPS
				// ----------------------------------------------------
				nav_roll_cd  = g.roll_limit_cd / 3;
				nav_pitch_cd = 0;

				if (failsafe != FAILSAFE_NONE){
					g.channel_throttle.servo_out = g.throttle_cruise;
				}
				break;

			case MANUAL:
				// servo_out is for Sim control only
				// ---------------------------------
				g.channel_roll.servo_out = g.channel_roll.pwm_to_angle();
				g.channel_pitch.servo_out = g.channel_pitch.pwm_to_angle();
				g.channel_rudder.servo_out = g.channel_rudder.pwm_to_angle();
				break;
				//roll: -13788.000,  pitch: -13698.000,   thr: 0.000, rud: -13742.000

		}
	}
}

static void update_navigation()
{
	// wp_distance is in ACTUAL meters, not the *100 meters we get from the GPS
	// ------------------------------------------------------------------------

	// distance and bearing calcs only
	if(control_mode == AUTO){
		verify_commands();
	}else{

		switch(control_mode){
			case LOITER:
			case RTL:
			case GUIDED:
				update_loiter();
				calc_bearing_error();
				break;

		}
	}
}


static void update_alt()
{
	#if HIL_MODE == HIL_MODE_ATTITUDE
		current_loc.alt = g_gps->altitude;
	#else
		// this function is in place to potentially add a sonar sensor in the future
		//altitude_sensor = BARO;

        if (barometer.healthy) {
            current_loc.alt = (1 - g.altitude_mix) * g_gps->altitude;			// alt_MSL centimeters (meters * 100)
            current_loc.alt += g.altitude_mix * (read_barometer() + home.alt);
        } else if (g_gps->fix) {
            current_loc.alt = g_gps->altitude; // alt_MSL centimeters (meters * 100)
        }
	#endif

        geofence_check(true);

		// Calculate new climb rate
		//if(medium_loopCounter == 0 && slow_loopCounter == 0)
		//	add_altitude_data(millis() / 100, g_gps->altitude / 10);
}