OEM615.h

00001     
00002 #pragma pack(1)  //this forces the structure to be packed on byte boundaries (with no byte filler)
00003 //set up the GPS message header in a structure to enable easy reading -- see the OEM615 manual (Table 4, page 24)
00004 struct MESSAGEHEADER   
00005 {
00006     char synchAA;  //1st synch word
00007     char synch44;  //2nd synch word
00008     char synch12;  //3rd synch word
00009     unsigned char headerLength;  //always 28
00010     unsigned short messageID;  //42 (BESTPOS) , 43 (RANGE) , or 99 (BESTVEL), 
00011     char messageType;  //always = 0 for binary
00012     unsigned char portAddress;  //0x20 for COM1
00013     unsigned short messageLength; //not including header or CRC
00014     unsigned short sequence;  //typically 0
00015     unsigned char idleTime;  //Time the processor is idle, in the last second
00016     unsigned char timeStatus; //Enum Indicating quality of the GPS reference time
00017     unsigned short GPSweek;   //GPS reference week
00018     unsigned long GPSTime_msecs; //from beginning of week
00019     unsigned long receiverStatus; //32-bits representing the status of hardware and software
00020     unsigned short reserved;
00021     unsigned short receiverSWversion;  //receiver software build number
00022 };
00023 MESSAGEHEADER *msgHeader[4];
00024 
00025 #pragma pack(1)
00026 //structure for OEM615 BESTVEL log message  (page 314)
00027 struct OEM615BESTVEL
00028 {
00029     MESSAGEHEADER msgHeader;
00030     int solStatus;                      //solution status
00031     //solutionStatusOEMStar solStatus;  //solution status
00032     int velType;                        //position or velocity type
00033     //velTypeOEMStar posType;           //position or velocity type   
00034     float latency;
00035     float age;
00036     double horizontalSpeed;         //horizontal velocity vector magnitude (m/s)
00037     double heading;                 //deg from North called TRK GND in specification
00038     double verticalSpeed;           //vertical velocity magnitude (m/s)
00039     float reserved;
00040     unsigned long CRC;
00041 };
00042 
00043 /*  Solution Status descritpion from OEMV manual
00044 0   SOL_COMPUTED        Solution computed
00045 1   INSUFFICIENT_OBS    Insufficient observations
00046 2   NO_CONVERGENCE      No convergence
00047 3   SINGULARITY         Singularity at parameters matrix
00048 4   COV_TRACE           Covariance trace exceeds maximum (trace > 1000 m)
00049 5   TEST_DIST           Test distance exceeded (maximum of 3 rejections if distance >10 km)
00050 6   COLD_START          Not yet converged from cold start
00051 7   V_H_LIMIT           Height or velocity limits exceeded
00052 8   VARIANCE            Variance exceeds limits
00053 9   RESIDUALS           Residuals are too large
00054 10  DELTA_POS           Delta position is too large
00055 11  NEGATIVE_VAR        Negative variance
00056 12  Reserved
00057 13  INTEGRITY_WARNING   Large residuals make position unreliable
00058 18  PENDING             
00059 19  INVALID_FIX         The fixed position, entered using the FIX POSITION command, is not valid
00060 20  UNAUTHORIZED        Position type is unauthorized - HP or XP 
00061 */
00062 
00063 #pragma pack(1)
00064 //structure for BESTPOS message 
00065 struct OEM615BESTPOS
00066 {
00067     MESSAGEHEADER msgHeader;
00068     int solStatus;                      //solution status
00069     //solutionStatusOEMStar solStatus;  //solution status
00070     int posType;                        //position or velocity type
00071     //posTypeOEMStar posType;           //position or velocity type
00072     double latitude;                    //latitude
00073     double longitude;                   //longitude
00074     double height;                      //height above mean sea level
00075     float undulation;                   //the realtionship between the geoid and the
00076                                         //ellipsoid of the chosen datum (m)
00077     char datumID[4];                    //datum ID is actually an enum that is not implemented
00078     float latitudeSTD;                  //latitude standard deviation
00079     float longitudeSTD;                 //longitude standard deviation
00080     float heightSTD;                    //height standard deviation
00081     char baseStationID[4];              //base station ID
00082     float diffAge;                      //differential age (s)
00083     float solutionAge;                  //solution age (s)
00084     unsigned char numSV;                //number of satellite vehicles tracked
00085     unsigned char numSolSV;             //number of satellite vehicles used in solution
00086     unsigned char numGGL1;              //number of GPS plus Glonass L1
00087     unsigned char res1;
00088     unsigned char res2;
00089     unsigned char extSolStatus;         //extended solution status
00090     unsigned char res3;
00091     unsigned char sigMask;              //signals used mask
00092     unsigned long CRC;
00093 };
00094 
00095 //GPS-specific pins
00096 DigitalOut GPS_Reset(p18);      //GPS RESET line
00097 InterruptIn PPSInt(p15);        // GPS 1PPS (timemark) from the OEM615
00098 InterruptIn IMUClock(p17);
00099 
00100 Timer timeFromPPS;
00101 unsigned long GPSTimemsecs = 0;
00102 double GPSTime = 0;
00103 int PPSTimeOffset = 0;
00104 
00105 //mbed tx/rx interface to the GPS COM1 port
00106 MODSERIAL GPS_COM1(p9,p10);  //this serial port communicates with the GPS receiver serial port (COM1)
00107 
00108 int test = 0;
00109 unsigned short messageCounter = 0;
00110 unsigned short savedMessageCounter = 0;
00111 const unsigned short maxGPSbytesPerSec = 1536;
00112 unsigned char msgBuffer[maxGPSbytesPerSec];  //array to contain one full second of GPS bytes
00113 const unsigned char maxGPSMessagesPerSec = 12;
00114 unsigned short messageLocation[maxGPSMessagesPerSec] = {0};  //stores the message location start within the message buffer
00115 
00116 //this code was taken from the Novatel Firmware document page 35
00117 #define CRC32_POLYNOMIAL 0xEDB88320L
00118 /* --------------------------------------------------------------------------
00119 Calculate a CRC value to be used by CRC calculation functions.
00120 -------------------------------------------------------------------------- */
00121 unsigned long CRC32Value(int i)
00122 {
00123     int j;
00124     unsigned long ulCRC;
00125     ulCRC = i;
00126     for ( j = 8 ; j > 0; j-- )
00127     {
00128         if ( ulCRC & 1 )
00129         ulCRC = ( ulCRC >> 1 ) ^ CRC32_POLYNOMIAL;
00130         else
00131         ulCRC >>= 1;
00132     }
00133     return ulCRC;
00134 } 
00135 
00136 /* --------------------------------------------------------------------------
00137 Calculates the CRC-32 of a block of data all at once
00138 //the CRC is c from the complete message (header plus data) but excluding (of course) the CRC at the end
00139 -------------------------------------------------------------------------- */
00140 unsigned long CalculateBlockCRC32(
00141         unsigned long ulCount,    /* Number of bytes in the data block */
00142         unsigned char *ucBuffer ) /* Data block */
00143 {
00144     unsigned long ulTemp1;
00145     unsigned long ulTemp2;
00146     unsigned long ulCRC = 0;
00147     while ( ulCount-- != 0 )
00148     {
00149         ulTemp1 = ( ulCRC >> 8 ) & 0x00FFFFFFL;
00150         ulTemp2 = CRC32Value( ((int) ulCRC ^ *ucBuffer++ ) & 0xff );
00151         ulCRC = ulTemp1 ^ ulTemp2;
00152     }
00153     return( ulCRC );
00154 }
00155 
00156 
00157 void sendASCII(char* ASCI_message, int numChars)
00158 {
00159     /////////////////////////////////////////////////
00160     //send an ASCII command to the GPS receiver
00161     /////////////////////////////////////////////////
00162 
00163     //char ASCI_message[] = "unlogall COM1";
00164     int as = numChars - 1;
00165     unsigned char CR = 0x0d;  //ASCII Carriage Return
00166     unsigned char LF = 0x0a;  //ASCII Line Feed
00167     
00168     //printf("%s", ch);
00169     //printf("\n");
00170 
00171     for (int i=0; i<as; i++) GPS_COM1.putc(ASCI_message[i]); 
00172     GPS_COM1.putc(CR);   //carriage return at end
00173     GPS_COM1.putc(LF);   //line feed at end
00174 };
00175 
00176 
00177 //see the mbed COOKBOOK for MODSERIAL
00178 //MODSERIAL is an easy to use library that extends Serial to add fully buffered input and output.
00179 void readSerialByte(MODSERIAL_IRQ_INFO *q)
00180 { 
00181     MODSERIAL *serial = q->serial;
00182     unsigned char synch0 = serial->getc();
00183     msgBuffer[byteCounter % maxGPSbytesPerSec] = synch0;
00184 
00185     //we need to trap the GPS message header byte-string 0xAA44121C
00186     //generate a 4-byte sliding-window sequence from the input bytes
00187     //shift last 4-byte value left 8 bits & push recently read byte (synch0) into low-order byte
00188     test = (test<<8) | synch0;  //
00189    
00190     if (test == 0xAA44121C) //test for the Receiver message header signature
00191     {
00192         messageLocation[perSecMessageCounter % maxGPSMessagesPerSec] = byteCounter-3; //store the location of this message (with 4 synch words)
00193         perSecMessageCounter++;
00194         messageDetected = true;
00195      }   
00196      //byteCounter reset to zero in main after the 1PPS is detected -- its NOT reset in the 1PPS ISR
00197      byteCounter++;     //total per-sec byte counter (reset to zero in main when 1PPS detected) 
00198 
00199 };
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