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#include <inttypes.h>
#include "ubx.h"
#include "timer0.h"
#include "uart0.h"
#include "printf_P.h"

// ------------------------------------------------------------------------------------------------
// defines

#define DAYS_FROM_JAN01YEAR0001_TO_JAN6_1980 722819 // the year 0 does not exist!
#define DAYS_PER_YEAR           365
#define DAYS_PER_LEAPYEAR       366
#define DAYS_PER_4YEARS         1461    //((3 * DAYS_PER_YEAR) + DAYS_PER_LEAPYEAR) // years dividable by 4 are leap years
#define DAYS_PER_100YEARS       36524   //((25 * DAYS_PER_4YEARS) - 1) // years dividable by 100 are no leap years
#define DAYS_PER_400YEARS       146097  //((4 * DAYS_PER_100YEARS) + 1L) // but years dividable by 400 are leap years
#define SECONDS_PER_MINUTE      60
#define MINUTES_PER_HOUR        60
#define HOURS_PER_DAY           24
#define DAYS_PER_WEEK           7
#define SECONDS_PER_HOUR        3600    //(SECONDS_PER_MINUTE * MINUTES_PER_HOUR)
#define SECONDS_PER_DAY         86400   //(SECONDS_PER_HOUR * HOURS_PER_DAY)
#define SECONDS_PER_WEEK        604800  //(SECONDS_PER_DAY * DAYS_PER_WEEK)

// days per month in normal and leap years
const uint32_t   Leap[ 13 ] = { 0,  31,  60,  91, 121, 152, 182, 213, 244, 274, 305, 335, 366 };
const uint32_t Normal[ 13 ]     = { 0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };

#define LEAP_SECONDS_FROM_1980  15 // the last one was on the Dec 31th 2008

// message sync bytes
#define UBX_SYNC1_CHAR  0xB5
#define UBX_SYNC2_CHAR  0x62
// protocoll identifier
#define UBX_CLASS_NAV   0x01
// message id
#define UBX_ID_POSLLH   0x02
#define UBX_ID_SOL              0x06
#define UBX_ID_VELNED   0x12

// ------------------------------------------------------------------------------------------------
// typedefs

// ubx parser state
typedef enum
{
UBXSTATE_IDLE,
UBXSTATE_SYNC1,
UBXSTATE_SYNC2,
UBXSTATE_CLASS,
UBXSTATE_LEN1,
UBXSTATE_LEN2,
UBXSTATE_DATA,
UBXSTATE_CKA,
UBXSTATE_CKB
} ubxState_t;

typedef struct
{
uint32_t        itow;           // ms GPS Millisecond Time of Week
int32_t         frac;           // ns remainder of rounded ms above
int16_t         week;           // GPS week
uint8_t         GPSfix;         // GPSfix Type, range 0..6
uint8_t         Flags;          // Navigation Status Flags
int32_t         ECEF_X;         // cm ECEF X coordinate
int32_t         ECEF_Y;         // cm ECEF Y coordinate
int32_t         ECEF_Z;         // cm ECEF Z coordinate
int32_t         PAcc;           // cm 3D Position Accuracy Estimate
int32_t         ECEFVX;         // cm/s ECEF X velocity
int32_t         ECEFVY;         // cm/s ECEF Y velocity
int32_t         ECEFVZ;         // cm/s ECEF Z velocity
uint32_t        SAcc;           // cm/s Speed Accuracy Estimate
uint16_t        PDOP;           // 0.01 Position DOP
uint8_t         res1;           // reserved
uint8_t         numSV;          // Number of SVs used in navigation solution
uint32_t        res2;           // reserved
uint8_t         Status;     // invalid/newdata/processed
} __attribute__((packed)) ubx_nav_sol_t;

typedef struct
{
uint32_t        itow;           // ms  GPS Millisecond Time of Week
int32_t         VEL_N;          // cm/s  NED north velocity
int32_t         VEL_E;          // cm/s  NED east velocity
int32_t         VEL_D;          // cm/s  NED down velocity
int32_t         Speed;          // cm/s  Speed (3-D)
int32_t         GSpeed;         // cm/s  Ground Speed (2-D)
uint32_t        SAcc;           // cm/s  Speed Accuracy Estimate
uint32_t        CAcc;           // deg  Course / Heading Accuracy Estimate
uint8_t         Status;         // invalid/newdata/processed
} __attribute__((packed)) ubx_nav_velned_t;

typedef struct
{
uint32_t        itow;           // ms GPS Millisecond Time of Week
int32_t         LON;            // 1e-07 deg Longitude
int32_t         LAT;            // 1e-07 deg Latitude
int32_t         HEIGHT;         // mm Height above Ellipsoid
int32_t         HMSL;           // mm Height above mean sea level
uint32_t        Hacc;           // mm Horizontal Accuracy Estimate
uint32_t        Vacc;           // mm Vertical Accuracy Estimate
uint8_t         Status;         // invalid/newdata/processed
} __attribute__((packed)) ubx_nav_posllh_t;

//------------------------------------------------------------------------------------
// global variables

// local buffers for the incomming ubx messages
volatile ubx_nav_sol_t          UbxSol    = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, INVALID};
volatile ubx_nav_posllh_t       UbxPosLlh = {0,0,0,0,0,0,0, INVALID};
volatile ubx_nav_velned_t       UbxVelNed = {0,0,0,0,0,0,0,0,0, INVALID};

uint16_t CheckGPSOkay = 0;

// shared buffer
gps_data_t              GPSData = {{0,0,0,INVALID},0,0,0,0,0,0,0, INVALID};

//------------------------------------------------------------------------------------
// functions

uint8_t IsLeapYear(uint16_t year)
{
if((year%400 == 0) || ( (year%4 == 0) && (year%100 != 0) ) ) return 1;
else return 0;
}

/********************************************************/
/*  Calculates the UTC Time from the GPS week and tow   */
/********************************************************/
void SetGPSTime(DateTime_t * pTimeStruct)
{
uint32_t Days, Seconds, Week;
uint16_t YearPart;
uint32_t * MonthDayTab = 0;
uint8_t  i;

// if GPS data show valid time data
if((UbxSol.Status != INVALID) && (UbxSol.Flags & FLAG_WKNSET) && (UbxSol.Flags & FLAG_TOWSET) )
{
Seconds = UbxSol.itow / 1000L;
Week = (uint32_t)UbxSol.week;
// correct leap seconds since 1980
if(Seconds < LEAP_SECONDS_FROM_1980)
{
Week--;
Seconds = SECONDS_PER_WEEK - LEAP_SECONDS_FROM_1980 + Seconds;
}
else Seconds -= LEAP_SECONDS_FROM_1980;

Days = DAYS_FROM_JAN01YEAR0001_TO_JAN6_1980;
Days += (Week * DAYS_PER_WEEK);
Days += Seconds / SECONDS_PER_DAY; // seperate days from GPS seconds of week

pTimeStruct->Year = 1;
YearPart = (uint16_t)(Days / DAYS_PER_400YEARS);
pTimeStruct->Year += YearPart * 400;
Days = Days % DAYS_PER_400YEARS;
YearPart = (uint16_t)(Days / DAYS_PER_100YEARS);
pTimeStruct->Year += YearPart * 100;
Days = Days % DAYS_PER_100YEARS;
YearPart = (uint16_t)(Days / DAYS_PER_4YEARS);
pTimeStruct->Year += YearPart * 4;
Days = Days % DAYS_PER_4YEARS;
if(Days < (3* DAYS_PER_YEAR)) YearPart = (uint16_t)(Days / DAYS_PER_YEAR);
else YearPart = 3;
pTimeStruct->Year += YearPart;
// calculate remaining days of year
Days -= (uint32_t)(YearPart *  DAYS_PER_YEAR);
Days += 1;
// check if current year is a leap year
if(IsLeapYear(pTimeStruct->Year)) MonthDayTab = (uint32_t*)Leap;
else MonthDayTab = (uint32_t*)Normal;
// seperate month and day from days of year
for ( i = 0; i < 12; i++ )
{
if ( (MonthDayTab[i]< Days) && (Days <= MonthDayTab[i+1]) )
{
pTimeStruct->Month = i+1;
pTimeStruct->Day = Days - MonthDayTab[i];
i = 12;
}
}
Seconds = Seconds % SECONDS_PER_DAY; // remaining seconds of current day
pTimeStruct->Hour = (uint8_t)(Seconds / SECONDS_PER_HOUR);
Seconds = Seconds % SECONDS_PER_HOUR; // remaining seconds of current hour
pTimeStruct->Min = (uint8_t)(Seconds / SECONDS_PER_MINUTE);
Seconds = Seconds % SECONDS_PER_MINUTE; // remaining seconds of current minute
pTimeStruct->Sec = (uint8_t)(Seconds);
pTimeStruct->mSec  = (uint16_t)(UbxSol.itow % 1000L);
pTimeStruct->Valid = 1;
}
else
{
pTimeStruct->Valid = 0;
}
}

/********************************************************/
/*                  Initialize UBX Parser               */
/********************************************************/
void UBX_Init(void)
{
printf("\r\n UBX init...");
// mark msg buffers invalid
UbxSol.Status = INVALID;
UbxPosLlh.Status = INVALID;
UbxVelNed.Status = INVALID;
GPSData.Status = INVALID;
printf("ok");
}

/********************************************************/
/*            Upate GPS data stcructure                 */
/********************************************************/
void Update_GPSData (void)
{
static uint16_t Ubx_Timeout = 0;
static uint8_t  Msg_Count = 0;

// the timeout is used to detect the delay between two message sets
// and is used for synchronisation so that always a set is collected
// that belongs together
// _______NAVSOL|POSLLH|VELNED|___________________NAVSOL|POSLLH|VELNED|_____________
//              |  8ms | 8ms  |         184 ms          |      |      |
// msg_count:   0      1      2                         0      1      2

if(CheckDelay(Ubx_Timeout))     Msg_Count = 0;
else Msg_Count++;
Ubx_Timeout = SetDelay(100); // reset ubx msg timeout

// if a new set of ubx messages was collected
if((Msg_Count >= 2))
{       // if set is complete
if((UbxSol.Status == NEWDATA) && (UbxPosLlh.Status == NEWDATA) && (UbxVelNed.Status == NEWDATA))
{
CheckGPSOkay++;
// update GPS data only if the status is INVALID or PROCESSED  and the last ubx message was received within less than 100 ms
if(GPSData.Status != NEWDATA) // if last data were processed
{ // wait for new data at all neccesary ubx messages
GPSData.Status = INVALID;
// NAV SOL
GPSData.Flags =                                 UbxSol.Flags;
GPSData.NumOfSats =                     UbxSol.numSV;
GPSData.SatFix =                                UbxSol.GPSfix;
GPSData.Position_Accuracy =             UbxSol.PAcc;
GPSData.Speed_Accuracy =                UbxSol.SAcc;
SetGPSTime(&SystemTime); // update system time
// NAV POSLLH
GPSData.Position.Status =               INVALID;
GPSData.Position.Longitude =    UbxPosLlh.LON;
GPSData.Position.Latitude =     UbxPosLlh.LAT;
GPSData.Position.Altitude =     UbxPosLlh.HMSL;
GPSData.Position.Status =               NEWDATA;
// NAV VELNED
GPSData.Speed_East =                    UbxVelNed.VEL_E;
GPSData.Speed_North =                   UbxVelNed.VEL_N;
GPSData.Speed_Top       =                       -UbxVelNed.VEL_D;
GPSData.Speed_Ground =                  UbxVelNed.GSpeed;

GPSData.Status = NEWDATA; // new data available
} // EOF if(GPSData.Status != NEWDATA)
} // EOF all ubx messages received
// set state to collect new data
UbxSol.Status =                                 PROCESSED;      // ready for new data
UbxPosLlh.Status =                              PROCESSED;      // ready for new data
UbxVelNed.Status =                              PROCESSED;      // ready for new data
}
}

/********************************************************/
/*                   UBX Parser                         */
/********************************************************/
void UBX_Parser(uint8_t c)
{
static ubxState_t ubxState = UBXSTATE_IDLE;
static uint16_t msglen;
static uint8_t cka, ckb;
static uint8_t *ubxP, *ubxEp, *ubxSp; // pointers to data currently transfered

//state machine
switch (ubxState)       // ubx message parser
{
case UBXSTATE_IDLE: // check 1st sync byte
if (c == UBX_SYNC1_CHAR) ubxState = UBXSTATE_SYNC1;
else ubxState = UBXSTATE_IDLE; // out of synchronization
break;

case UBXSTATE_SYNC1: // check 2nd sync byte
if (c == UBX_SYNC2_CHAR) ubxState = UBXSTATE_SYNC2;
else ubxState = UBXSTATE_IDLE; // out of synchronization
break;

case UBXSTATE_SYNC2: // check msg class to be NAV
if (c == UBX_CLASS_NAV) ubxState = UBXSTATE_CLASS;
else ubxState = UBXSTATE_IDLE; // unsupported message class
break;

case UBXSTATE_CLASS: // check message identifier
switch(c)
{
case UBX_ID_POSLLH: // geodetic position
ubxP =  (uint8_t *)&UbxPosLlh; // data start pointer
ubxEp = (uint8_t *)(&UbxPosLlh + 1); // data end pointer
ubxSp = (uint8_t *)&UbxPosLlh.Status; // status pointer
break;

ubxP =  (uint8_t *)&UbxSol; // data start pointer
ubxEp = (uint8_t *)(&UbxSol + 1); // data end pointer
ubxSp = (uint8_t *)&UbxSol.Status; // status pointer
break;

case UBX_ID_VELNED: // velocity vector in tangent plane
ubxP =  (uint8_t *)&UbxVelNed; // data start pointer
ubxEp = (uint8_t *)(&UbxVelNed + 1); // data end pointer
ubxSp = (uint8_t *)&UbxVelNed.Status; // status pointer
break;

default:                        // unsupported identifier
ubxState = UBXSTATE_IDLE;
break;
}
if (ubxState != UBXSTATE_IDLE)
{
ubxState = UBXSTATE_LEN1;
cka = UBX_CLASS_NAV + c;
ckb = UBX_CLASS_NAV + cka;
}
break;

case UBXSTATE_LEN1: // 1st message length byte
msglen = (uint16_t)c; // lowbyte first
cka += c;
ckb += cka;
ubxState = UBXSTATE_LEN2;
break;

case UBXSTATE_LEN2: // 2nd message length byte
msglen += ((uint16_t)c)<<8; // high byte last
cka += c;
ckb += cka;
// if the old data are not processed so far then break parsing now
// to avoid writing new data in ISR during reading by another function
if ( *ubxSp == NEWDATA )
{
ubxState = UBXSTATE_IDLE;
Update_GPSData(); //update GPS info respectively
}
else // data invalid or allready processd
{
*ubxSp = INVALID; // mark invalid during buffer filling
ubxState = UBXSTATE_DATA;
}
break;

case UBXSTATE_DATA: // collecting data
if (ubxP < ubxEp)
{
*ubxP++ = c; // copy curent data byte if any space is left
cka += c;
ckb += cka;
if (--msglen == 0)      ubxState = UBXSTATE_CKA; // switch to next state if all data was read
}
else // rx buffer overrun
{
ubxState = UBXSTATE_IDLE;
}
break;

case UBXSTATE_CKA:
if (c == cka) ubxState = UBXSTATE_CKB;
else
{
*ubxSp = INVALID;
ubxState = UBXSTATE_IDLE;
}
break;

case UBXSTATE_CKB:
if (c == ckb)
{
*ubxSp = NEWDATA; // new data are valid
Update_GPSData(); //update GPS info respectively
}
else
{       // if checksum not match then set data invalid
*ubxSp = INVALID;
}
ubxState = UBXSTATE_IDLE; // ready to parse new data
break;

default: // unknown ubx state
ubxState = UBXSTATE_IDLE;
break;

}
}