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#include "main.h"
// ubx protocol parser state machine
#define UBXSTATE_IDLE 0
#define UBXSTATE_SYNC1 1
#define UBXSTATE_SYNC2 2
#define UBXSTATE_CLASS 3
#define UBXSTATE_LEN1 4
#define UBXSTATE_LEN2 5
#define UBXSTATE_DATA 6
#define UBXSTATE_CKA 7
#define UBXSTATE_CKB 8
// ublox protocoll identifier
#define UBX_CLASS_NAV 0x01
#define UBX_ID_POSLLH 0x02
#define UBX_ID_POSUTM 0x08
#define UBX_ID_STATUS 0x03
#define UBX_ID_VELNED 0x12
#define UBX_SYNC1_CHAR 0xB5
#define UBX_SYNC2_CHAR 0x62
typedef struct {
uint32_t ITOW; // ms GPS Millisecond Time of Week
uint8_t GPSfix; // GPSfix Type, range 0..6
uint8_t Flags; // Navigation Status Flags
uint8_t DiffS; // Differential Status
uint8_t res; // reserved
uint32_t TTFF; // Time to first fix (millisecond time tag)
uint32_t MSSS; // Milliseconds since Startup / Reset
uint8_t Status;
} GPS_STATUS_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;
} GPS_POSLLH_t;
typedef struct {
uint32_t ITOW; // ms GPS Millisecond Time of Week
int32_t EAST; // cm UTM Easting
int32_t NORTH; // cm UTM Nording
int32_t ALT; // cm altitude
uint8_t ZONE; // UTM zone number
uint8_t HEM; // Hemisphere Indicator (0=North, 1=South)
uint8_t Status;
} GPS_POSUTM_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
uint32_t Speed; // cm/s Speed (3-D)
uint32_t GSpeed; // cm/s Ground Speed (2-D)
int32_t Heading; // 1e-05 deg Heading 2-D
uint32_t SAcc; // cm/s Speed Accuracy Estimate
uint32_t CAcc; // deg Course / Heading Accuracy Estimate
uint8_t Status;
} GPS_VELNED_t;
GPS_STATUS_t GpsStatus = {0,0,0,0,0,0,0, INVALID};
GPS_POSLLH_t GpsPosLlh = {0,0,0,0,0,0,0, INVALID};
GPS_POSUTM_t GpsPosUtm = {0,0,0,0,0,0, INVALID};
GPS_VELNED_t GpsVelNed = {0,0,0,0,0,0,0,0,0, INVALID};
GPS_INFO_t GPSInfo = {0,0,0,0,0,0,0,0,0,0, INVALID};
volatile uint8_t GPSTimeout = 0;
void UpdateGPSInfo (void)
{
if (GpsStatus.Status == VALID) // valid packet
{
GPSInfo.satfix = GpsStatus.GPSfix;
GpsStatus.Status = PROCESSED; // never update old data
}
if (GpsPosLlh.Status == VALID) // valid packet
{
GPSInfo.longitude = GpsPosLlh.LON;
GPSInfo.latitude = GpsPosLlh.LAT;
GPSInfo.altitude = GpsPosLlh.HEIGHT;
GpsPosLlh.Status = PROCESSED; // never update old data
}
if (GpsPosUtm.Status == VALID) // valid packet
{
GPSInfo.utmeast = GpsPosUtm.EAST;
GPSInfo.utmnorth = GpsPosUtm.NORTH;
GPSInfo.utmalt = GpsPosUtm.ALT;
GpsPosUtm.Status = PROCESSED; // never update old data
}
if (GpsVelNed.Status == VALID) // valid packet
{
GPSInfo.veleast = GpsVelNed.VEL_E;
GPSInfo.velnorth = GpsVelNed.VEL_N;
GPSInfo.veltop = -GpsVelNed.VEL_D;
GPSInfo.velground = GpsVelNed.GSpeed;
GpsVelNed.Status = PROCESSED; // never update old data
}
if (GpsStatus.Status != INVALID)
{
GPSInfo.status = VALID; // set valid if data are updated
}
}
// this function should be called within the UART RX ISR
void ubx_parser(uint8_t c)
{
static uint8_t ubxstate = UBXSTATE_IDLE;
static uint8_t cka, ckb;
static uint16_t msglen;
static int8_t *ubxP, *ubxEp, *ubxSp; // pointers to data currently transfered
switch(ubxstate)
{
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_POSUTM: // utm position
ubxP = (int8_t *)&GpsPosUtm; // data start pointer
ubxEp = (int8_t *)(&GpsPosUtm + sizeof(GPS_POSUTM_t)); // data end pointer
ubxSp = (int8_t *)&GpsPosUtm.Status; // status pointer
break;
case UBX_ID_POSLLH: // geodetic position
ubxP = (int8_t *)&GpsPosLlh; // data start pointer
ubxEp = (int8_t *)(&GpsPosLlh + sizeof(GPS_POSLLH_t)); // data end pointer
ubxSp = (int8_t *)&GpsPosLlh.Status; // status pointer
break;
case UBX_ID_STATUS: // receiver status
ubxP = (int8_t *)&GpsStatus; // data start pointer
ubxEp = (int8_t *)(&GpsStatus + sizeof(GPS_STATUS_t)); // data end pointer
ubxSp = (int8_t *)&GpsStatus.Status; // status pointer
break;
case UBX_ID_VELNED: // velocity vector in tangent plane
ubxP = (int8_t *)&GpsVelNed; // data start pointer
ubxEp = (int8_t *)(&GpsVelNed + sizeof(GPS_VELNED_t)); // data end pointer
ubxSp = (int8_t *)&GpsVelNed.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 = c;
cka += c;
ckb += cka;
ubxstate = UBXSTATE_LEN2;
break;
case UBXSTATE_LEN2: // 2nd message length byte
msglen += ((uint16_t)c)<<8;
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 == VALID ) ubxstate = UBXSTATE_IDLE;
else // data invalid or allready processd
{
*ubxSp = INVALID;
ubxstate = UBXSTATE_DATA;
}
break;
case UBXSTATE_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
break;
case UBXSTATE_CKA:
if (c == cka) ubxstate = UBXSTATE_CKB;
else
{
*ubxSp = INVALID;
ubxstate = UBXSTATE_IDLE;
}
break;
case UBXSTATE_CKB:
if (c == ckb)
{
*ubxSp = VALID; // new data are valid
ROT_FLASH;
UpdateGPSInfo(); //update GPS info respectively
GPSTimeout = 255;
}
else
{ // if checksum not fit then set data invalid
*ubxSp = INVALID;
}
ubxstate = UBXSTATE_IDLE; // ready to parse new data
break;
default: // unknown ubx state
ubxstate = UBXSTATE_IDLE;
break;
}
}