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author | Harsh Sharma <92harshsharma@gmail.com> | 2018-06-13 13:24:54 -0500 |
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committer | Harsh Sharma <92harshsharma@gmail.com> | 2018-06-13 13:24:54 -0500 |
commit | 7c383be1542368f2601015d9fc2a417197677677 (patch) | |
tree | bc06453f879cbadf65fd88123c506956403c5684 /libloragw/src/loragw_gps.c | |
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Initial Commit
Diffstat (limited to 'libloragw/src/loragw_gps.c')
-rw-r--r-- | libloragw/src/loragw_gps.c | 835 |
1 files changed, 835 insertions, 0 deletions
diff --git a/libloragw/src/loragw_gps.c b/libloragw/src/loragw_gps.c new file mode 100644 index 0000000..c0e0ded --- /dev/null +++ b/libloragw/src/loragw_gps.c @@ -0,0 +1,835 @@ +/* + / _____) _ | | +( (____ _____ ____ _| |_ _____ ____| |__ + \____ \| ___ | (_ _) ___ |/ ___) _ \ + _____) ) ____| | | || |_| ____( (___| | | | +(______/|_____)_|_|_| \__)_____)\____)_| |_| + (C)2013 Semtech-Cycleo + +Description: + Library of functions to manage a GNSS module (typically GPS) for accurate + timestamping of packets and synchronisation of gateways. + A limited set of module brands/models are supported. + +License: Revised BSD License, see LICENSE.TXT file include in the project +Maintainer: Michael Coracin +*/ + + +/* -------------------------------------------------------------------------- */ +/* --- DEPENDANCIES --------------------------------------------------------- */ + +#define _GNU_SOURCE /* needed for qsort_r to be defined */ +#include <stdint.h> /* C99 types */ +#include <stdbool.h> /* bool type */ +#include <stdio.h> /* printf fprintf */ +#include <string.h> /* memcpy */ + +#include <time.h> /* struct timespec */ +#include <fcntl.h> /* open */ +#include <termios.h> /* tcflush */ +#include <math.h> /* modf */ + +#include <stdlib.h> + +#include "loragw_gps.h" + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE MACROS ------------------------------------------------------- */ + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0])) +#if DEBUG_GPS == 1 + #define DEBUG_MSG(args...) fprintf(stderr, args) + #define DEBUG_ARRAY(a,b,c) for(a=0;a<b;++a) fprintf(stderr,"%x.",c[a]);fprintf(stderr,"end\n") + #define CHECK_NULL(a) if(a==NULL){fprintf(stderr,"%s:%d: ERROR: NULL POINTER AS ARGUMENT\n", __FUNCTION__, __LINE__);return LGW_GPS_ERROR;} +#else + #define DEBUG_MSG(args...) + #define DEBUG_ARRAY(a,b,c) for(a=0;a!=0;){} + #define CHECK_NULL(a) if(a==NULL){return LGW_GPS_ERROR;} +#endif +#define TRACE() fprintf(stderr, "@ %s %d\n", __FUNCTION__, __LINE__); + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE CONSTANTS ---------------------------------------------------- */ + +#define TS_CPS 1E6 /* count-per-second of the timestamp counter */ +#define PLUS_10PPM 1.00001 +#define MINUS_10PPM 0.99999 +#define DEFAULT_BAUDRATE B9600 + +#define UBX_MSG_NAVTIMEGPS_LEN 16 + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE VARIABLES ---------------------------------------------------- */ + + +/* result of the NMEA parsing */ +static short gps_yea = 0; /* year (2 or 4 digits) */ +static short gps_mon = 0; /* month (1-12) */ +static short gps_day = 0; /* day of the month (1-31) */ +static short gps_hou = 0; /* hours (0-23) */ +static short gps_min = 0; /* minutes (0-59) */ +static short gps_sec = 0; /* seconds (0-60)(60 is for leap second) */ +static float gps_fra = 0.0; /* fractions of seconds (<1) */ +static bool gps_time_ok = false; +static int16_t gps_week = 0; /* GPS week number of the navigation epoch */ +static uint32_t gps_iTOW = 0; /* GPS time of week in milliseconds */ +static int32_t gps_fTOW = 0; /* Fractional part of iTOW (+/-500000) in nanosec */ + +static short gps_dla = 0; /* degrees of latitude */ +static double gps_mla = 0.0; /* minutes of latitude */ +static char gps_ola = 0; /* orientation (N-S) of latitude */ +static short gps_dlo = 0; /* degrees of longitude */ +static double gps_mlo = 0.0; /* minutes of longitude */ +static char gps_olo = 0; /* orientation (E-W) of longitude */ +static short gps_alt = 0; /* altitude */ +static bool gps_pos_ok = false; + +static char gps_mod = 'N'; /* GPS mode (N no fix, A autonomous, D differential) */ +static short gps_sat = 0; /* number of satellites used for fix */ + +static struct termios ttyopt_restore; + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE FUNCTIONS DECLARATION ---------------------------------------- */ + +static int nmea_checksum(const char *nmea_string, int buff_size, char *checksum); + +static char nibble_to_hexchar(uint8_t a); + +static bool validate_nmea_checksum(const char *serial_buff, int buff_size); + +static bool match_label(const char *s, char *label, int size, char wildcard); + +static int str_chop(char *s, int buff_size, char separator, int *idx_ary, int max_idx); + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE FUNCTIONS DEFINITION ----------------------------------------- */ + +/* +Calculate the checksum for a NMEA string +Skip the first '$' if necessary and calculate checksum until '*' character is +reached (or buff_size exceeded). +Checksum must point to a 2-byte (or more) char array. +Return position of the checksum in the string +*/ +static int nmea_checksum(const char *nmea_string, int buff_size, char *checksum) { + int i = 0; + uint8_t check_num = 0; + + /* check input parameters */ + if ((nmea_string == NULL) || (checksum == NULL) || (buff_size <= 1)) { + DEBUG_MSG("Invalid parameters for nmea_checksum\n"); + return -1; + } + + /* skip the first '$' if necessary */ + if (nmea_string[i] == '$') { + i += 1; + } + + /* xor until '*' or max length is reached */ + while (nmea_string[i] != '*') { + check_num ^= nmea_string[i]; + i += 1; + if (i >= buff_size) { + DEBUG_MSG("Maximum length reached for nmea_checksum\n"); + return -1; + } + } + + /* Convert checksum value to 2 hexadecimal characters */ + checksum[0] = nibble_to_hexchar(check_num / 16); /* upper nibble */ + checksum[1] = nibble_to_hexchar(check_num % 16); /* lower nibble */ + + return i + 1; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +static char nibble_to_hexchar(uint8_t a) { + if (a < 10) { + return '0' + a; + } else if (a < 16) { + return 'A' + (a-10); + } else { + return '?'; + } +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +/* +Calculate the checksum of a NMEA frame and compare it to the checksum that is +present at the end of it. +Return true if it matches +*/ +static bool validate_nmea_checksum(const char *serial_buff, int buff_size) { + int checksum_index; + char checksum[2]; /* 2 characters to calculate NMEA checksum */ + + checksum_index = nmea_checksum(serial_buff, buff_size, checksum); + + /* could we calculate a verification checksum ? */ + if (checksum_index < 0) { + DEBUG_MSG("ERROR: IMPOSSIBLE TO PARSE NMEA SENTENCE\n"); + return false; + } + + /* check if there are enough char in the serial buffer to read checksum */ + if (checksum_index >= (buff_size - 2)) { + DEBUG_MSG("ERROR: IMPOSSIBLE TO READ NMEA SENTENCE CHECKSUM\n"); + return false; + } + + /* check the checksum per se */ + if ((serial_buff[checksum_index] == checksum[0]) && (serial_buff[checksum_index+1] == checksum[1])) { + return true; + } else { + DEBUG_MSG("ERROR: NMEA CHECKSUM %c%c DOESN'T MATCH VERIFICATION CHECKSUM %c%c\n", serial_buff[checksum_index], serial_buff[checksum_index+1], checksum[0], checksum[1]); + return false; + } +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +/* +Return true if the "label" string (can contain wildcard characters) matches +the begining of the "s" string +*/ +static bool match_label(const char *s, char *label, int size, char wildcard) { + int i; + + for (i=0; i < size; i++) { + if (label[i] == wildcard) continue; + if (label[i] != s[i]) return false; + } + return true; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +/* +Chop a string into smaller strings +Replace every separator in the input character buffer by a null character so +that all s[index] are valid strings. +Populate an array of integer 'idx_ary' representing indexes of token in the +string. +buff_size and max_idx are there to prevent segfaults. +Return the number of token found (number of idx_ary filled). +*/ +int str_chop(char *s, int buff_size, char separator, int *idx_ary, int max_idx) { + int i = 0; /* index in the string */ + int j = 0; /* index in the result array */ + + if ((s == NULL) || (buff_size < 0) || (separator == 0) || (idx_ary == NULL) || (max_idx < 0)) { + /* unsafe to do anything */ + return -1; + } + if ((buff_size == 0) || (max_idx == 0)) { + /* nothing to do */ + return 0; + } + s[buff_size - 1] = 0; /* add string terminator at the end of the buffer, just to be sure */ + idx_ary[j] = 0; + j += 1; + /* loop until string terminator is reached */ + while (s[i] != 0) { + if (s[i] == separator) { + s[i] = 0; /* replace separator by string terminator */ + if (j >= max_idx) { /* no more room in the index array */ + return j; + } + idx_ary[j] = i+1; /* next token start after replaced separator */ + ++j; + } + ++i; + } + return j; +} + +/* -------------------------------------------------------------------------- */ +/* --- PUBLIC FUNCTIONS DEFINITION ------------------------------------------ */ + +int lgw_gps_enable(char *tty_path, char *gps_family, speed_t target_brate, int *fd_ptr) { + int i; + struct termios ttyopt; /* serial port options */ + int gps_tty_dev; /* file descriptor to the serial port of the GNSS module */ + uint8_t ubx_cmd_timegps[UBX_MSG_NAVTIMEGPS_LEN] = { + 0xB5, 0x62, /* UBX Sync Chars */ + 0x06, 0x01, /* CFG-MSG Class/ID */ + 0x08, 0x00, /* Payload length */ + 0x01, 0x20, 0x00, 0x01, 0x01, 0x00, 0x00, 0x00, /* Enable NAV-TIMEGPS output on serial */ + 0x32, 0x94 }; /* Checksum */ + ssize_t num_written; + + /* check input parameters */ + CHECK_NULL(tty_path); + CHECK_NULL(fd_ptr); + + /* open TTY device */ + gps_tty_dev = open(tty_path, O_RDWR | O_NOCTTY); + if (gps_tty_dev <= 0) { + DEBUG_MSG("ERROR: TTY PORT FAIL TO OPEN, CHECK PATH AND ACCESS RIGHTS\n"); + return LGW_GPS_ERROR; + } + *fd_ptr = gps_tty_dev; + + /* manage the different GPS modules families */ + if (gps_family == NULL) { + DEBUG_MSG("WARNING: this version of GPS module may not be supported\n"); + } else if (strncmp(gps_family, "ubx7", 4) != 0) { + /* The current implementation relies on proprietary messages from U-Blox */ + /* GPS modules (UBX, NAV-TIMEGPS...) and has only be tested with a u-blox 7. */ + /* Those messages allow to get NATIVE GPS time (no leap seconds) required */ + /* for class-B handling and GPS synchronization */ + /* see lgw_parse_ubx() function for details */ + DEBUG_MSG("WARNING: this version of GPS module may not be supported\n"); + } + + /* manage the target bitrate */ + if (target_brate != 0) { + DEBUG_MSG("WARNING: target_brate parameter ignored for now\n"); // TODO + } + + /* get actual serial port configuration */ + i = tcgetattr(gps_tty_dev, &ttyopt); + if (i != 0) { + DEBUG_MSG("ERROR: IMPOSSIBLE TO GET TTY PORT CONFIGURATION\n"); + return LGW_GPS_ERROR; + } + + /* Save current serial port configuration for restoring later */ + memcpy(&ttyopt_restore, &ttyopt, sizeof ttyopt); + + /* update baudrates */ + cfsetispeed(&ttyopt, DEFAULT_BAUDRATE); + cfsetospeed(&ttyopt, DEFAULT_BAUDRATE); + + /* update terminal parameters */ + /* The following configuration should allow to: + - Get ASCII NMEA messages + - Get UBX binary messages + - Send UBX binary commands + Note: as binary data have to be read/written, we need to disable + various character processing to avoid loosing data */ + /* Control Modes */ + ttyopt.c_cflag |= CLOCAL; /* local connection, no modem control */ + ttyopt.c_cflag |= CREAD; /* enable receiving characters */ + ttyopt.c_cflag |= CS8; /* 8 bit frames */ + ttyopt.c_cflag &= ~PARENB; /* no parity */ + ttyopt.c_cflag &= ~CSTOPB; /* one stop bit */ + /* Input Modes */ + ttyopt.c_iflag |= IGNPAR; /* ignore bytes with parity errors */ + ttyopt.c_iflag &= ~ICRNL; /* do not map CR to NL on input*/ + ttyopt.c_iflag &= ~IGNCR; /* do not ignore carriage return on input */ + ttyopt.c_iflag &= ~IXON; /* disable Start/Stop output control */ + ttyopt.c_iflag &= ~IXOFF; /* do not send Start/Stop characters */ + /* Output Modes */ + ttyopt.c_oflag = 0; /* disable everything on output as we only write binary */ + /* Local Modes */ + ttyopt.c_lflag &= ~ICANON; /* disable canonical input - cannot use with binary input */ + ttyopt.c_lflag &= ~ISIG; /* disable check for INTR, QUIT, SUSP special characters */ + ttyopt.c_lflag &= ~IEXTEN; /* disable any special control character */ + ttyopt.c_lflag &= ~ECHO; /* do not echo back every character typed */ + ttyopt.c_lflag &= ~ECHOE; /* does not erase the last character in current line */ + ttyopt.c_lflag &= ~ECHOK; /* do not echo NL after KILL character */ + + /* settings for non-canonical mode + read will block for until the lesser of VMIN or requested chars have been received */ + ttyopt.c_cc[VMIN] = LGW_GPS_MIN_MSG_SIZE; + ttyopt.c_cc[VTIME] = 0; + + /* set new serial ports parameters */ + i = tcsetattr(gps_tty_dev, TCSANOW, &ttyopt); + if (i != 0){ + DEBUG_MSG("ERROR: IMPOSSIBLE TO UPDATE TTY PORT CONFIGURATION\n"); + return LGW_GPS_ERROR; + } + tcflush(gps_tty_dev, TCIOFLUSH); + + /* Send UBX CFG NAV-TIMEGPS message to tell GPS module to output native GPS time */ + /* This is a binary message, serial port has to be properly configured to handle this */ + num_written = write (gps_tty_dev, ubx_cmd_timegps, UBX_MSG_NAVTIMEGPS_LEN); + if (num_written != UBX_MSG_NAVTIMEGPS_LEN) { + DEBUG_MSG("ERROR: Failed to write on serial port (written=%d)\n", (int) num_written); + } + + /* get timezone info */ + tzset(); + + /* initialize global variables */ + gps_time_ok = false; + gps_pos_ok = false; + gps_mod = 'N'; + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_gps_disable(int fd) { + int i; + + /* restore serial ports parameters */ + i = tcsetattr(fd, TCSANOW, &ttyopt_restore); + if (i != 0){ + DEBUG_MSG("ERROR: IMPOSSIBLE TO RESTORE TTY PORT CONFIGURATION\n"); + return LGW_GPS_ERROR; + } + tcflush(fd, TCIOFLUSH); + + i = close(fd); + if (i <= 0) { + DEBUG_MSG("ERROR: TTY PORT FAIL TO CLOSE\n"); + return LGW_GPS_ERROR; + } + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +enum gps_msg lgw_parse_ubx(const char *serial_buff, size_t buff_size, size_t *msg_size) { + bool valid = 0; /* iTOW, fTOW and week validity */ + unsigned int payload_length; + uint8_t ck_a, ck_b; + uint8_t ck_a_rcv, ck_b_rcv; + unsigned int i; + + *msg_size = 0; /* ensure msg_size alway receives a value */ + + /* check input parameters */ + if (serial_buff == NULL) { + return IGNORED; + } + if (buff_size < 8) { + DEBUG_MSG("ERROR: TOO SHORT TO BE A VALID UBX MESSAGE\n"); + return IGNORED; + } + + /* display received serial data and checksum */ + DEBUG_MSG("Note: parsing UBX frame> "); + for (i=0; i<buff_size; i++) { + DEBUG_MSG("%02x ", serial_buff[i]); + } + DEBUG_MSG("\n"); + + /* Check for UBX sync chars 0xB5 0x62 */ + if ((serial_buff[0] == (char)0xB5) && (serial_buff[1] == (char)0x62)) { + + /* Get payload length to compute message size */ + payload_length = (uint8_t)serial_buff[4]; + payload_length |= (uint8_t)serial_buff[5] << 8; + *msg_size = 6 + payload_length + 2; /* header + payload + checksum */ + + /* check for complete message in buffer */ + if(*msg_size <= buff_size) { + /* Validate checksum of message */ + ck_a_rcv = serial_buff[*msg_size-2]; /* received checksum */ + ck_b_rcv = serial_buff[*msg_size-1]; /* received checksum */ + /* Use 8-bit Fletcher Algorithm to compute checksum of actual payload */ + ck_a = 0; ck_b = 0; + for (i=0; i<(4 + payload_length); i++) { + ck_a = ck_a + serial_buff[i+2]; + ck_b = ck_b + ck_a; + } + + /* Compare checksums and parse if OK */ + if ((ck_a == ck_a_rcv) && (ck_b == ck_b_rcv)) { + /* Check for Class 0x01 (NAV) and ID 0x20 (NAV-TIMEGPS) */ + if ((serial_buff[2] == 0x01) && (serial_buff[3] == 0x20)) { + /* Check validity of information */ + valid = serial_buff[17] & 0x3; /* towValid, weekValid */ + if (valid) { + /* Parse buffer to extract GPS time */ + /* Warning: payload byte ordering is Little Endian */ + gps_iTOW = (uint8_t)serial_buff[6]; + gps_iTOW |= (uint8_t)serial_buff[7] << 8; + gps_iTOW |= (uint8_t)serial_buff[8] << 16; + gps_iTOW |= (uint8_t)serial_buff[9] << 24; /* GPS time of week, in ms */ + + gps_fTOW = (uint8_t)serial_buff[10]; + gps_fTOW |= (uint8_t)serial_buff[11] << 8; + gps_fTOW |= (uint8_t)serial_buff[12] << 16; + gps_fTOW |= (uint8_t)serial_buff[13] << 24; /* Fractional part of iTOW, in ns */ + + gps_week = (uint8_t)serial_buff[14]; + gps_week |= (uint8_t)serial_buff[15] << 8; /* GPS week number */ + + gps_time_ok = true; +#if 0 + /* For debug */ + { + short ubx_gps_hou = 0; /* hours (0-23) */ + short ubx_gps_min = 0; /* minutes (0-59) */ + short ubx_gps_sec = 0; /* seconds (0-59) */ + + /* Format GPS time in hh:mm:ss based on iTOW */ + ubx_gps_sec = (gps_iTOW / 1000) % 60; + ubx_gps_min = (gps_iTOW / 1000 / 60) % 60; + ubx_gps_hou = (gps_iTOW / 1000 / 60 / 60) % 24; + printf(" GPS time = %02d:%02d:%02d\n", ubx_gps_hou, ubx_gps_min, ubx_gps_sec); + } +#endif + } else { /* valid */ + gps_time_ok = false; + } + + return UBX_NAV_TIMEGPS; + } else if ((serial_buff[2] == 0x05) && (serial_buff[3] == 0x00)) { + DEBUG_MSG("NOTE: UBX ACK-NAK received\n"); + return IGNORED; + } else if ((serial_buff[2] == 0x05) && (serial_buff[3] == 0x01)) { + DEBUG_MSG("NOTE: UBX ACK-ACK received\n"); + return IGNORED; + } else { /* not a supported message */ + DEBUG_MSG("ERROR: UBX message is not supported (%02x %02x)\n", serial_buff[2], serial_buff[3]); + return IGNORED; + } + } else { /* checksum failed */ + DEBUG_MSG("ERROR: UBX message is corrupted, checksum failed\n"); + return INVALID; + } + } else { /* message contains less bytes than indicated by header */ + DEBUG_MSG("ERROR: UBX message incomplete\n"); + return INCOMPLETE; + } + } else { /* Not a UBX message */ + /* Ignore messages which are not UBX ones for now */ + return IGNORED; + } +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +enum gps_msg lgw_parse_nmea(const char *serial_buff, int buff_size) { + int i, j, k; + int str_index[30]; /* string index from the string chopping */ + int nb_fields; /* number of strings detected by string chopping */ + char parser_buf[256]; /* parsing modifies buffer so need a local copy */ + + /* check input parameters */ + if (serial_buff == NULL) { + return UNKNOWN; + } + + if(buff_size > (int)(sizeof(parser_buf) - 1)) { + DEBUG_MSG("Note: input string to big for parsing\n"); + return INVALID; + } + + /* look for some NMEA sentences in particular */ + if (buff_size < 8) { + DEBUG_MSG("ERROR: TOO SHORT TO BE A VALID NMEA SENTENCE\n"); + return UNKNOWN; + } else if (!validate_nmea_checksum(serial_buff, buff_size)) { + DEBUG_MSG("Warning: invalid NMEA sentence (bad checksum)\n"); + return INVALID; + } else if (match_label(serial_buff, "$G?RMC", 6, '?')) { + /* + NMEA sentence format: $xxRMC,time,status,lat,NS,long,EW,spd,cog,date,mv,mvEW,posMode*cs<CR><LF> + Valid fix: $GPRMC,083559.34,A,4717.11437,N,00833.91522,E,0.004,77.52,091202,,,A*00 + No fix: $GPRMC,,V,,,,,,,,,,N*00 + */ + memcpy(parser_buf, serial_buff, buff_size); + parser_buf[buff_size] = '\0'; + nb_fields = str_chop(parser_buf, buff_size, ',', str_index, ARRAY_SIZE(str_index)); + if (nb_fields != 13) { + DEBUG_MSG("Warning: invalid RMC sentence (number of fields)\n"); + return IGNORED; + } + /* parse GPS status */ + gps_mod = *(parser_buf + str_index[12]); /* get first character, no need to bother with sscanf */ + if ((gps_mod != 'N') && (gps_mod != 'A') && (gps_mod != 'D')) { + gps_mod = 'N'; + } + /* parse complete time */ + i = sscanf(parser_buf + str_index[1], "%2hd%2hd%2hd%4f", &gps_hou, &gps_min, &gps_sec, &gps_fra); + j = sscanf(parser_buf + str_index[9], "%2hd%2hd%2hd", &gps_day, &gps_mon, &gps_yea); + if ((i == 4) && (j == 3)) { + if ((gps_mod == 'A') || (gps_mod == 'D')) { + gps_time_ok = true; + DEBUG_MSG("Note: Valid RMC sentence, GPS locked, date: 20%02d-%02d-%02dT%02d:%02d:%06.3fZ\n", gps_yea, gps_mon, gps_day, gps_hou, gps_min, gps_fra + (float)gps_sec); + } else { + gps_time_ok = false; + DEBUG_MSG("Note: Valid RMC sentence, no satellite fix, estimated date: 20%02d-%02d-%02dT%02d:%02d:%06.3fZ\n", gps_yea, gps_mon, gps_day, gps_hou, gps_min, gps_fra + (float)gps_sec); + } + } else { + /* could not get a valid hour AND date */ + gps_time_ok = false; + DEBUG_MSG("Note: Valid RMC sentence, mode %c, no date\n", gps_mod); + } + return NMEA_RMC; + } else if (match_label(serial_buff, "$G?GGA", 6, '?')) { + /* + NMEA sentence format: $xxGGA,time,lat,NS,long,EW,quality,numSV,HDOP,alt,M,sep,M,diffAge,diffStation*cs<CR><LF> + Valid fix: $GPGGA,092725.00,4717.11399,N,00833.91590,E,1,08,1.01,499.6,M,48.0,M,,*5B + */ + memcpy(parser_buf, serial_buff, buff_size); + parser_buf[buff_size] = '\0'; + nb_fields = str_chop(parser_buf, buff_size, ',', str_index, ARRAY_SIZE(str_index)); + if (nb_fields != 15) { + DEBUG_MSG("Warning: invalid GGA sentence (number of fields)\n"); + return IGNORED; + } + /* parse number of satellites used for fix */ + sscanf(parser_buf + str_index[7], "%hd", &gps_sat); + /* parse 3D coordinates */ + i = sscanf(parser_buf + str_index[2], "%2hd%10lf", &gps_dla, &gps_mla); + gps_ola = *(parser_buf + str_index[3]); + j = sscanf(parser_buf + str_index[4], "%3hd%10lf", &gps_dlo, &gps_mlo); + gps_olo = *(parser_buf + str_index[5]); + k = sscanf(parser_buf + str_index[9], "%hd", &gps_alt); + if ((i == 2) && (j == 2) && (k == 1) && ((gps_ola=='N')||(gps_ola=='S')) && ((gps_olo=='E')||(gps_olo=='W'))) { + gps_pos_ok = true; + DEBUG_MSG("Note: Valid GGA sentence, %d sat, lat %02ddeg %06.3fmin %c, lon %03ddeg%06.3fmin %c, alt %d\n", gps_sat, gps_dla, gps_mla, gps_ola, gps_dlo, gps_mlo, gps_olo, gps_alt); + } else { + /* could not get a valid latitude, longitude AND altitude */ + gps_pos_ok = false; + DEBUG_MSG("Note: Valid GGA sentence, %d sat, no coordinates\n", gps_sat); + } + return NMEA_GGA; + } else { + DEBUG_MSG("Note: ignored NMEA sentence\n"); /* quite verbose */ + return IGNORED; + } +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_gps_get(struct timespec *utc, struct timespec *gps_time, struct coord_s *loc, struct coord_s *err) { + struct tm x; + time_t y; + double intpart, fractpart; + + if (utc != NULL) { + if (!gps_time_ok) { + DEBUG_MSG("ERROR: NO VALID TIME TO RETURN\n"); + return LGW_GPS_ERROR; + } + memset(&x, 0, sizeof(x)); + if (gps_yea < 100) { /* 2-digits year, 20xx */ + x.tm_year = gps_yea + 100; /* 100 years offset to 1900 */ + } else { /* 4-digits year, Gregorian calendar */ + x.tm_year = gps_yea - 1900; + } + x.tm_mon = gps_mon - 1; /* tm_mon is [0,11], gps_mon is [1,12] */ + x.tm_mday = gps_day; + x.tm_hour = gps_hou; + x.tm_min = gps_min; + x.tm_sec = gps_sec; + y = mktime(&x) - timezone; /* need to substract timezone bc mktime assumes time vector is local time */ + if (y == (time_t)(-1)) { + DEBUG_MSG("ERROR: FAILED TO CONVERT BROKEN-DOWN TIME\n"); + return LGW_GPS_ERROR; + } + utc->tv_sec = y; + utc->tv_nsec = (int32_t)(gps_fra * 1e9); + } + if (gps_time != NULL) { + if (!gps_time_ok) { + DEBUG_MSG("ERROR: NO VALID TIME TO RETURN\n"); + return LGW_GPS_ERROR; + } + fractpart = modf(((double)gps_iTOW / 1E3) + ((double)gps_fTOW / 1E9), &intpart); + /* Number of seconds since beginning on current GPS week */ + gps_time->tv_sec = (time_t)intpart; + /* Number of seconds since GPS epoch 06.Jan.1980 */ + gps_time->tv_sec += (time_t)gps_week * 604800; /* day*hours*minutes*secondes: 7*24*60*60; */ + /* Fractional part in nanoseconds */ + gps_time->tv_nsec = (long)(fractpart * 1E9); + } + if (loc != NULL) { + if (!gps_pos_ok) { + DEBUG_MSG("ERROR: NO VALID POSITION TO RETURN\n"); + return LGW_GPS_ERROR; + } + loc->lat = ((double)gps_dla + (gps_mla/60.0)) * ((gps_ola == 'N')?1.0:-1.0); + loc->lon = ((double)gps_dlo + (gps_mlo/60.0)) * ((gps_olo == 'E')?1.0:-1.0); + loc->alt = gps_alt; + } + if (err != NULL) { + DEBUG_MSG("Warning: localization error processing not implemented yet\n"); + err->lat = 0.0; + err->lon = 0.0; + err->alt = 0; + } + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_gps_sync(struct tref *ref, uint32_t count_us, struct timespec utc, struct timespec gps_time) { + double cnt_diff; /* internal concentrator time difference (in seconds) */ + double utc_diff; /* UTC time difference (in seconds) */ + double slope; /* time slope between new reference and old reference (for sanity check) */ + + bool aber_n0; /* is the update value for synchronization aberrant or not ? */ + static bool aber_min1 = false; /* keep track of whether value at sync N-1 was aberrant or not */ + static bool aber_min2 = false; /* keep track of whether value at sync N-2 was aberrant or not */ + + CHECK_NULL(ref); + + /* calculate the slope */ + + cnt_diff = (double)(count_us - ref->count_us) / (double)(TS_CPS); /* uncorrected by xtal_err */ + utc_diff = (double)(utc.tv_sec - (ref->utc).tv_sec) + (1E-9 * (double)(utc.tv_nsec - (ref->utc).tv_nsec)); + + /* detect aberrant points by measuring if slope limits are exceeded */ + if (utc_diff != 0) { // prevent divide by zero + slope = cnt_diff/utc_diff; + if ((slope > PLUS_10PPM) || (slope < MINUS_10PPM)) { + DEBUG_MSG("Warning: correction range exceeded\n"); + aber_n0 = true; + } else { + aber_n0 = false; + } + } else { + DEBUG_MSG("Warning: aberrant UTC value for synchronization\n"); + aber_n0 = true; + } + + /* watch if the 3 latest sync point were aberrant or not */ + if (aber_n0 == false) { + /* value no aberrant -> sync with smoothed slope */ + ref->systime = time(NULL); + ref->count_us = count_us; + ref->utc.tv_sec = utc.tv_sec; + ref->utc.tv_nsec = utc.tv_nsec; + ref->gps.tv_sec = gps_time.tv_sec; + ref->gps.tv_nsec = gps_time.tv_nsec; + ref->xtal_err = slope; + aber_min2 = aber_min1; + aber_min1 = aber_n0; + return LGW_GPS_SUCCESS; + } else if (aber_n0 && aber_min1 && aber_min2) { + /* 3 successive aberrant values -> sync reset (keep xtal_err) */ + ref->systime = time(NULL); + ref->count_us = count_us; + ref->utc.tv_sec = utc.tv_sec; + ref->utc.tv_nsec = utc.tv_nsec; + ref->gps.tv_sec = gps_time.tv_sec; + ref->gps.tv_nsec = gps_time.tv_nsec; + /* reset xtal_err only if the present value is out of range */ + if ((ref->xtal_err > PLUS_10PPM) || (ref->xtal_err < MINUS_10PPM)) { + ref->xtal_err = 1.0; + } + DEBUG_MSG("Warning: 3 successive aberrant sync attempts, sync reset\n"); + aber_min2 = aber_min1; + aber_min1 = aber_n0; + return LGW_GPS_SUCCESS; + } else { + /* only 1 or 2 successive aberrant values -> ignore and return an error */ + aber_min2 = aber_min1; + aber_min1 = aber_n0; + return LGW_GPS_ERROR; + } + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_cnt2utc(struct tref ref, uint32_t count_us, struct timespec *utc) { + double delta_sec; + double intpart, fractpart; + long tmp; + + CHECK_NULL(utc); + if ((ref.systime == 0) || (ref.xtal_err > PLUS_10PPM) || (ref.xtal_err < MINUS_10PPM)) { + DEBUG_MSG("ERROR: INVALID REFERENCE FOR CNT -> UTC CONVERSION\n"); + return LGW_GPS_ERROR; + } + + /* calculate delta in seconds between reference count_us and target count_us */ + delta_sec = (double)(count_us - ref.count_us) / (TS_CPS * ref.xtal_err); + + /* now add that delta to reference UTC time */ + fractpart = modf (delta_sec , &intpart); + tmp = ref.utc.tv_nsec + (long)(fractpart * 1E9); + if (tmp < (long)1E9) { /* the nanosecond part doesn't overflow */ + utc->tv_sec = ref.utc.tv_sec + (time_t)intpart; + utc->tv_nsec = tmp; + } else { /* must carry one second */ + utc->tv_sec = ref.utc.tv_sec + (time_t)intpart + 1; + utc->tv_nsec = tmp - (long)1E9; + } + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_utc2cnt(struct tref ref, struct timespec utc, uint32_t *count_us) { + double delta_sec; + + CHECK_NULL(count_us); + if ((ref.systime == 0) || (ref.xtal_err > PLUS_10PPM) || (ref.xtal_err < MINUS_10PPM)) { + DEBUG_MSG("ERROR: INVALID REFERENCE FOR UTC -> CNT CONVERSION\n"); + return LGW_GPS_ERROR; + } + + /* calculate delta in seconds between reference utc and target utc */ + delta_sec = (double)(utc.tv_sec - ref.utc.tv_sec); + delta_sec += 1E-9 * (double)(utc.tv_nsec - ref.utc.tv_nsec); + + /* now convert that to internal counter tics and add that to reference counter value */ + *count_us = ref.count_us + (uint32_t)(delta_sec * TS_CPS * ref.xtal_err); + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_cnt2gps(struct tref ref, uint32_t count_us, struct timespec *gps_time) { + double delta_sec; + double intpart, fractpart; + long tmp; + + CHECK_NULL(gps_time); + if ((ref.systime == 0) || (ref.xtal_err > PLUS_10PPM) || (ref.xtal_err < MINUS_10PPM)) { + DEBUG_MSG("ERROR: INVALID REFERENCE FOR CNT -> GPS CONVERSION\n"); + return LGW_GPS_ERROR; + } + + /* calculate delta in milliseconds between reference count_us and target count_us */ + delta_sec = (double)(count_us - ref.count_us) / (TS_CPS * ref.xtal_err); + + /* now add that delta to reference GPS time */ + fractpart = modf (delta_sec , &intpart); + tmp = ref.gps.tv_nsec + (long)(fractpart * 1E9); + if (tmp < (long)1E9) { /* the nanosecond part doesn't overflow */ + gps_time->tv_sec = ref.gps.tv_sec + (time_t)intpart; + gps_time->tv_nsec = tmp; + } else { /* must carry one second */ + gps_time->tv_sec = ref.gps.tv_sec + (time_t)intpart + 1; + gps_time->tv_nsec = tmp - (long)1E9; + } + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_gps2cnt(struct tref ref, struct timespec gps_time, uint32_t *count_us) { + double delta_sec; + + CHECK_NULL(count_us); + if ((ref.systime == 0) || (ref.xtal_err > PLUS_10PPM) || (ref.xtal_err < MINUS_10PPM)) { + DEBUG_MSG("ERROR: INVALID REFERENCE FOR GPS -> CNT CONVERSION\n"); + return LGW_GPS_ERROR; + } + + /* calculate delta in seconds between reference gps time and target gps time */ + delta_sec = (double)(gps_time.tv_sec - ref.gps.tv_sec); + delta_sec += 1E-9 * (double)(gps_time.tv_nsec - ref.gps.tv_nsec); + + /* now convert that to internal counter tics and add that to reference counter value */ + *count_us = ref.count_us + (uint32_t)(delta_sec * TS_CPS * ref.xtal_err); + + return LGW_GPS_SUCCESS; +} + +/* --- EOF ------------------------------------------------------------------ */ |