courselog.gpsutils
Class SerialGPSConnection

java.lang.Object
  courselog.gpsutils.SerialGPSConnection

All Implemented Interfaces:

java.lang.Runnable

public class SerialGPSConnection
extends java.lang.Object
implements java.lang.Runnable

Handles a GPS connected to a Serial port. Generates Measurements (MeasuredPoint) each time a new measurement is issued by the receiver. Handles a listener to the connection to receive all new points. Configuration of the device is planned but ot implemented : - enable differential measurements (WAAS or EGNOS) when available - initialize for fast re-start - power saving mode

Field Summary

protected static byte[]	bGPGGA Identifier of a GGA NMEA sentence ("GPGGA").
protected static byte[]	bGPGSV Identifier of a GSV NMEA sentence ("GPGSV").
protected static byte[]	bGPRMC Identifier of a RMC NMEA sentence ("GPRMC").
static int	BUFFMAX Maximum serial port buffer size (256 chars).
MeasuredPoint	currentPoint Current point received from the GPS.
ewe.io.SerialPortOptions	currentSPO Port options that were used to open the serial port to the GPS.
int	debugCounter Debugging counter to verify problems with connections
protected static java.lang.String	fGPGGA Values sequence in a GGA sentence ("VVCVCIIVVCVCVI").
protected static java.lang.String	fGPGSV Values sequence in a GSV sentence ("IIIIIIIIIIIIIIIIIII").
protected static java.lang.String	fGPRMC Values sequence in a RMC sentence ("VCVCVCVVIVVC").
ewe.io.Stream	inGPS Input reader of the GPS serial port.
static boolean	isEmulating Flag indicating that the receive should read from a "tmpGPSLog.txt" file in order to emulate the presence of a receiver.
static boolean	isLogging Flag indicating that the receiver should log its data.
static java.lang.String	logFileName For debugging, GPS data may be logged into a file.
protected ewe.ui.EventListener	myListener Listener to this receiver.
protected ReceiverEvent	myPointEvent Event passed to listeners when a new point is decoded.
protected ReceiverEvent	myStatusEvent Event passed to listeners when the status of the receiver changes.
static int	NBLINESINBUFFER Number of lines to buffer before parsing NMEA.
static int	NBSATMAX Maximum number of satellites status to record (20).
protected ewe.io.FileOutputStream	outLog Stream to output the logged GPS data to.
ewe.sys.mThread	reader Thread reading the GPS receiver values and issueing events when a new point is decoded.
int	status Status of the receiver (one of STATUS_XXX values).
static int	STATUS_GPSLOST GPs is connected via the serial port but the GPS produces no valid fix.
static int	STATUS_NOK GPS receiver does not transmit through the serial port.
static int	STATUS_OK Receiver status is fine!
char[]	vNMEACar Array containing single char values decoded from NMEA (20 char).
int[]	vNMEAInt Array containing integer values decoded from NMEA (20 ints).
double[]	vNMEAVal Array containing double values decoded from NMEA (20 double).
int[]	vSatAz State of the GPS, azimtuhs of the satellites currently available.
int[]	vSatEl State of the GPS, elevations of the satellites currently available.
int[]	vSatPRN State of the GPS, idenfiers of the satellites currently available.
int[]	vSatSNR State of the GPS, signal to noise of the satellites currently available.

Constructor Summary

SerialGPSConnection(ewe.io.SerialPortOptions spo, ewe.ui.EventListener listener)
Creates a new instance of SerialGPSConnection

Method Summary

void	analyseNMEAValues(byte[] b, int iSt, int iEnd) When a valid sentence is received, analyses it to update the current point values.
void	close() Stop the GPS reception.
static SerialGPSConnection	getAnActiveSerialGPSConnection(ewe.io.SerialPortOptions spo, ewe.ui.EventListener listener) Factory for serial connection creating an active connection.
static ewe.io.SerialPortOptions	getDefaultPortOptions() Provides a set of default port options.
static java.lang.String	getPortOptionsAsString(ewe.io.SerialPortOptions forSPO) Format forSPO in a string that will be readable later.
static ewe.io.SerialPortOptions	getPortOptionsFromString(java.lang.String sO) Interprets a string with port name, rate, etc, into serial port options.
java.lang.String	getUTCFromGPS() Get UTC provided by the GPS receiver.
boolean	isCheckSumOK(int valChk, byte[] charChk, int idxChk) Verify checksum of an NMEA sentence.
int	parseNMEAContent(byte[] b, int len) Reads in the buffer to find NMEA sentences and analyses them in case there are.
void	run() Method reading the GPS actived in thread reader.
void	setListener(ewe.ui.EventListener list) Sets the listener of this receiver.
boolean	startLog() Start to log received data fom the serial port.
boolean	startReading() Starts the GPS reading thread myReader.
void	stopLog() Stops logging GPS data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

STATUS_OK

public static final int STATUS_OK

Receiver status is fine!

See Also:

Constant Field Values

STATUS_GPSLOST

public static final int STATUS_GPSLOST

GPs is connected via the serial port but the GPS produces no valid fix.

See Also:

Constant Field Values

STATUS_NOK

public static final int STATUS_NOK

GPS receiver does not transmit through the serial port.

See Also:

Constant Field Values

BUFFMAX

public static int BUFFMAX

Maximum serial port buffer size (256 chars). If bigger, data is blocked long before being exploited, if smaller, partial NMEA sentences are received and not usable. NMEA specifies that the sentences should not exceed 80 chars.

NBLINESINBUFFER

public static int NBLINESINBUFFER

Number of lines to buffer before parsing NMEA.

NBSATMAX

public static int NBSATMAX

Maximum number of satellites status to record (20).

bGPGGA

protected static final byte[] bGPGGA

Identifier of a GGA NMEA sentence ("GPGGA").

fGPGGA

protected static final java.lang.String fGPGGA

Values sequence in a GGA sentence ("VVCVCIIVVCVCVI").

See Also:

Constant Field Values

bGPRMC

protected static final byte[] bGPRMC

Identifier of a RMC NMEA sentence ("GPRMC").

fGPRMC

protected static final java.lang.String fGPRMC

Values sequence in a RMC sentence ("VCVCVCVVIVVC").

See Also:

Constant Field Values

bGPGSV

protected static final byte[] bGPGSV

Identifier of a GSV NMEA sentence ("GPGSV").

fGPGSV

protected static final java.lang.String fGPGSV

Values sequence in a GSV sentence ("IIIIIIIIIIIIIIIIIII").

See Also:

Constant Field Values

logFileName

public static java.lang.String logFileName

For debugging, GPS data may be logged into a file. ("tmpGPSLog.txt")

isLogging

public static boolean isLogging

Flag indicating that the receiver should log its data.

isEmulating

public static boolean isEmulating

Flag indicating that the receive should read from a "tmpGPSLog.txt" file in order to emulate the presence of a receiver.

debugCounter

public int debugCounter

Debugging counter to verify problems with connections

outLog

protected ewe.io.FileOutputStream outLog

Stream to output the logged GPS data to.

currentPoint

public MeasuredPoint currentPoint

Current point received from the GPS. Same object is used, fields are updated depending on the received data.

status

public int status

Status of the receiver (one of STATUS_XXX values).

reader

public ewe.sys.mThread reader

Thread reading the GPS receiver values and issueing events when a new point is decoded.

currentSPO

public ewe.io.SerialPortOptions currentSPO

Port options that were used to open the serial port to the GPS.

inGPS

public ewe.io.Stream inGPS

Input reader of the GPS serial port.

myPointEvent

protected ReceiverEvent myPointEvent

Event passed to listeners when a new point is decoded. Same object is reused.

myStatusEvent

protected ReceiverEvent myStatusEvent

Event passed to listeners when the status of the receiver changes. Same object is reused.

myListener

protected ewe.ui.EventListener myListener

Listener to this receiver.

vNMEAInt

public int[] vNMEAInt

Array containing integer values decoded from NMEA (20 ints).

vNMEAVal

public double[] vNMEAVal

Array containing double values decoded from NMEA (20 double).

vNMEACar

public char[] vNMEACar

Array containing single char values decoded from NMEA (20 char).

vSatPRN

public int[] vSatPRN

State of the GPS, idenfiers of the satellites currently available.

vSatAz

public int[] vSatAz

State of the GPS, azimtuhs of the satellites currently available.

vSatEl

public int[] vSatEl

State of the GPS, elevations of the satellites currently available.

vSatSNR

public int[] vSatSNR

State of the GPS, signal to noise of the satellites currently available.

Constructor Detail

SerialGPSConnection

public SerialGPSConnection(ewe.io.SerialPortOptions spo,
                           ewe.ui.EventListener listener)

Creates a new instance of SerialGPSConnection

Parameters:

spo - Serial port options to use for connection to the GPS.

listener - Listener which will receive the state and points events.

Method Detail

getAnActiveSerialGPSConnection

public static SerialGPSConnection getAnActiveSerialGPSConnection(ewe.io.SerialPortOptions spo,
                                                                 ewe.ui.EventListener listener)

Factory for serial connection creating an active connection. Call this method instead of the constructor and get a connection generating data. If this method is called within an mThread, it tries to reconnect every 2s an only returns if interrupted. Otherwise (not in an mThread) returns a new connection even if connection fails.

Parameters:

spo - Serial ort options to use for the connection

listener - Listener for GPS events

Returns:

A new instance of a SerialGPSConnection with an active connection to a GPS device. null if the connection process is interrupted.

startReading

public boolean startReading()

Starts the GPS reading thread myReader.

Returns:

true is the thread started, false otherwise.

run

public void run()

Method reading the GPS actived in thread reader. This method also parses NMEA values and activates the listener in the reader thread. May only be stopped by an interruption on reader thread.

Specified by:

run in interface java.lang.Runnable

parseNMEAContent

public int parseNMEAContent(byte[] b,
                            int len)

Reads in the buffer to find NMEA sentences and analyses them in case there are. Also checks the checksum of each sentence.

Parameters:

b - Buffer to read in.

len - Length of usable chars in the buffer, starting at 0.

Returns:

Number of chars consummed by the analysis of NMEA sentences.

analyseNMEAValues

public void analyseNMEAValues(byte[] b,
                              int iSt,
                              int iEnd)

When a valid sentence is received, analyses it to update the current point values.

 GGA : get UTC, lat, lon, nbsats, alt, hdop
 RMC : get date, speed, heading
 GSV : updates satellite status (no event is generated
      but data is available for polling).

When a point is fully analysed, generate a ReceiverEvent. If fix is not valid, modify status accordingly.

Parameters:

b - Buffer to read in.

iSt - Index of starting location of the NMEA sentence.

iEnd - Index of ending location of the sentence.

close

public void close()

Stop the GPS reception. Stops the thread and close the log if any.

startLog

public boolean startLog()

Start to log received data fom the serial port. Data is appended to the file which only grows...

Returns:

true if correct, false otherwise.

stopLog

public void stopLog()

Stops logging GPS data.

isCheckSumOK

public boolean isCheckSumOK(int valChk,
                            byte[] charChk,
                            int idxChk)

Verify checksum of an NMEA sentence. Checksum is a XOR of all characters after the '$' and before the '*'.

Parameters:

valChk - Computed checksum of the sentence.

charChk - Hexadecimal value of the checksum read from the port.

idxChk - Index of the checksum value in charChk.

Returns:

True if valChk equals interpretation of charChk.

getPortOptionsFromString

public static ewe.io.SerialPortOptions getPortOptionsFromString(java.lang.String sO)

Interprets a string with port name, rate, etc, into serial port options. Example : "{name=COM6:,rate=4800,bits=8,parity=0,stop=1}"

Parameters:

sO - String containing the description of the options.

Returns:

Initialised new Serial port options.

getDefaultPortOptions

public static ewe.io.SerialPortOptions getDefaultPortOptions()

Provides a set of default port options. Corresponds to what works with my configuration : {name=COM6:,rate=9600,bits=8,parity=0,stop=1}

Returns:

Default port options.

getPortOptionsAsString

public static java.lang.String getPortOptionsAsString(ewe.io.SerialPortOptions forSPO)

Format forSPO in a string that will be readable later.

Parameters:

forSPO - Options to format.

Returns:

String that may be parsed later to reconfigure options.

getUTCFromGPS

public java.lang.String getUTCFromGPS()

Get UTC provided by the GPS receiver.

Returns:

Time from receiver as a string "HH:MM:SS"

setListener

public void setListener(ewe.ui.EventListener list)

Sets the listener of this receiver. Should not be null if an event occurs.

Parameters:

list - Listener to dispatch events to.