Module: spice_interface

The SPICE interface class gets time and planetary body information from the JPL ephemeris library

The module PDF Description contains further information on this module’s function, how to run it, as well as testing.

class SpiceInterface : public SysModel
#include <spice_interface.h>

spice interface class

Public Functions

SpiceInterface()

This constructor initializes the variables that spice uses. Most of them are not intended to be changed, but a couple are user configurable.

~SpiceInterface()

The only needed activity in the destructor is to delete the spice I/O buffer that was allocated in the constructor

void UpdateState(uint64_t CurrentSimNanos)

This method is the interface point between the upper level simulation and the SPICE interface at runtime. It calls all of the necessary lower level methods.

Return

void

Parameters

  • CurrentSimNanos: The current clock time for the simulation

int loadSpiceKernel(char *kernelName, const char *dataPath)

This method loads a requested SPICE kernel into the system memory. It is its own method because we have to load several SPICE kernels in for our application. Note that they are stored in the SPICE library and are not held locally in this object.

Return

int Zero for success one for failure

Parameters

  • kernelName: The name of the kernel we are loading

  • dataPath: The path to the data area on the filesystem

int unloadSpiceKernel(char *kernelName, const char *dataPath)

This method unloads a requested SPICE kernel into the system memory. It is its own method because we have to load several SPICE kernels in for our application. Note that they are stored in the SPICE library and are not held locally in this object.

Return

int Zero for success one for failure

Parameters

  • kernelName: The name of the kernel we are unloading

  • dataPath: The path to the data area on the filesystem

std::string getCurrentTimeString()

class method

void SelfInit()

This method initializes the object. It creates the output messages, initializes the SPICE kernels, and initializes the planet/time data that gets used at run.

Return

void

void CrossInit()

Should subscribe to module input messages. However, the epoch message is subscribed to in the SelfInit() routine due to how Spice is being loaded and setup.

Return

void

void Reset(uint64_t CurrentSimNanos)

Reset the module to origina configuration values.

Return

void

void initTimeData()

This method is used to initialize the zero-time that will be used to calculate all system time values in the Update method. It also creates the output message for time data

Return

void

void computeGPSData()

This method computes the GPS time data for the current elapsed time. It uses the total elapsed times at both the GPS epoch time and the current time to compute the GPS time (week, seconds, rollovers)

Return

void

void computePlanetData()

This method gets the state of each planet that has been added to the model and saves the information off into the planet array.

Return

void

void writeOutputMessages(uint64_t CurrentClock)

This method takes the values computed in the model and outputs them. It packages up the internal variables into the output structure definitions and puts them out on the messaging system

Return

void

Parameters

  • CurrentClock: The current simulation time (used for time stamping)

void clearKeeper()

class method

Public Members

std::string SPICEDataPath

Path on file to SPICE data

std::string referenceBase

Base reference frame to use

std::string zeroBase

Base zero point to use for states

std::string timeOutPicture

Optional parameter used to extract time strings

bool SPICELoaded

Boolean indicating to reload spice

int charBufferSize

avert your eyes we’re getting SPICE

uint8_t *spiceBuffer

General buffer to pass down to spice

std::string UTCCalInit

UTC time string for init time

std::string outputTimePort

Output time sampling port name to use

uint64_t outputBufferCount

Number of output buffers to use

std::vector<std::string> planetNames

Names of planets we want to track

std::vector<std::string> planetFrames

Optional vector of planet frame names. Default values are IAU_ + planet name

bool timeDataInit

Flag indicating whether time has been init

double J2000ETInit

s Seconds elapsed since J2000 at init

double J2000Current

s Current J2000 elapsed time

double julianDateCurrent

s Current JulianDate

double GPSSeconds

s Current GPS seconds

uint16_t GPSWeek

Current GPS week value

uint64_t GPSRollovers

Count on the number of GPS rollovers

std::string epochInMsgName

Message name of the epoch message (optional)

int64_t epochInMsgId

ID of the epoch message.

BSKLogger bskLogger

BSK Logging

Private Members

std::string GPSEpochTime

String for the GPS epoch

double JDGPSEpoch

s Epoch for GPS time. Saved for efficiency

int64_t timeOutMsgID

Output time message ID

std::map<uint32_t, SpicePlanetStateSimMsg> planetData

Internal vector of planets