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Diffstat (limited to 'libloragw/src/loragw_gps.c')
| -rw-r--r-- | libloragw/src/loragw_gps.c | 573 |
1 files changed, 573 insertions, 0 deletions
diff --git a/libloragw/src/loragw_gps.c b/libloragw/src/loragw_gps.c new file mode 100644 index 0000000..84db3b8 --- /dev/null +++ b/libloragw/src/loragw_gps.c @@ -0,0 +1,573 @@ +/* + / _____) _ | | +( (____ _____ ____ _| |_ _____ ____| |__ + \____ \| ___ | (_ _) ___ |/ ___) _ \ + _____) ) ____| | | || |_| ____( (___| | | | +(______/|_____)_|_|_| \__)_____)\____)_| |_| + ©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: Sylvain Miermont +*/ + + +/* -------------------------------------------------------------------------- */ +/* --- DEPENDANCIES --------------------------------------------------------- */ + +/* fix an issue between POSIX and C99 */ +#if __STDC_VERSION__ >= 199901L + #define _XOPEN_SOURCE 600 +#else + #define _XOPEN_SOURCE 500 +#endif + +#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> // DEBUG + +#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 + +/* -------------------------------------------------------------------------- */ +/* --- 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 + +/* -------------------------------------------------------------------------- */ +/* --- 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 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 */ + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE FUNCTIONS DECLARATION ---------------------------------------- */ + +int nmea_checksum(char *nmea_string, int buff_size, char *checksum); + +char nibble_to_hexchar(uint8_t a); + +bool validate_nmea_checksum(char *serial_buff, int buff_size); + +bool match_label(char *s, char *label, int size, char wildcard); + +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 '$' if necessary and calculate checksum until '*' character is +reached (or buff_size exceeded). +Checksum must point to a 2-byte (or more) char array. +Return position of the checksum in the string +*/ +int nmea_checksum(char *nmea_string, int buff_size, char *checksum) { + int i = 0; + uint8_t check_num = 0; + + /* check input parameters */ + if ((nmea_string == NULL) || (checksum == NULL) || (buff_size <= 1)) { + DEBUG_MSG("Invalid parameters for nmea_checksum\n"); + return -1; + } + + /* skip the first '$' 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; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +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 +*/ +bool validate_nmea_checksum(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 +*/ +bool match_label(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_familly, 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 */ + + /* 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_familly != NULL) { + DEBUG_MSG("WARNING: gps_familly parameter ignored for now\n"); // TODO + } + + /* 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; + } + + /* update baudrates */ + cfsetispeed(&ttyopt, DEFAULT_BAUDRATE); + cfsetospeed(&ttyopt, DEFAULT_BAUDRATE); + + /* update terminal parameters */ + 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 */ + ttyopt.c_iflag |= IGNPAR; /* ignore bytes with parity errors */ + ttyopt.c_iflag |= ICRNL; /* map CR to NL */ + ttyopt.c_iflag |= IGNCR; /* Ignore carriage return on input */ + ttyopt.c_lflag |= ICANON; /* enable canonical input */ + + /* 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); + + /* initialize global variables */ + gps_time_ok = false; + gps_pos_ok = false; + gps_mod = 'N'; + + return LGW_GPS_SUCCESS; +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +enum gps_msg lgw_parse_nmea(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 */ + + /* check input parameters */ + if (serial_buff == NULL) { + return UNKNOWN; + } + + /* display received serial data and checksum */ + DEBUG_MSG("Note: parsing NMEA frame> %s", serial_buff); + + /* 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 (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: $GPRMC,,V,,,,,,,,,,N*00 + */ + if (!validate_nmea_checksum(serial_buff, buff_size)) { + DEBUG_MSG("Warning: invalid RMC sentence (bad checksum)\n"); + return INVALID; + } + nb_fields = str_chop(serial_buff, buff_size, ',', str_index, ARRAY_SIZE(str_index)); + if (nb_fields != 13) { + DEBUG_MSG("Warning: invalid RMC sentence (number of fields)\n"); + return INVALID; + } + /* parse GPS status */ + gps_mod = *(serial_buff + str_index[12]); /* get first character, no need to bother with sscanf */ + if ((gps_mod != 'N') && (gps_mod != 'A') && (gps_mod != 'D')) { + gps_mod = 'N'; + } + /* parse complete time */ + i = sscanf(serial_buff + str_index[1], "%2hd%2hd%2hd%4f", &gps_hou, &gps_min, &gps_sec, &gps_fra); + j = sscanf(serial_buff + str_index[9], "%2hd%2hd%2hd", &gps_day, &gps_mon, &gps_yea); + if ((i == 4) && (j == 3)) { + if ((gps_mod == 'A') || (gps_mod == 'D')) { + gps_time_ok = true; + DEBUG_MSG("Note: Valid RMC sentence, GPS locked, date: 20%02d-%02d-%02dT%02d:%02d:%06.3fZ\n", gps_yea, gps_mon, gps_day, gps_hou, gps_min, gps_fra + (float)gps_sec); + } else { + gps_time_ok = false; + DEBUG_MSG("Note: Valid RMC sentence, no satellite fix, estimated date: 20%02d-%02d-%02dT%02d:%02d:%06.3fZ\n", gps_yea, gps_mon, gps_day, gps_hou, gps_min, gps_fra + (float)gps_sec); + } + } else { + /* could not get a valid hour AND date */ + gps_time_ok = false; + DEBUG_MSG("Note: Valid RMC sentence, mode %c, no date\n", gps_mod); + } + return NMEA_RMC; + } else if (match_label(serial_buff, "$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 + */ + if (!validate_nmea_checksum(serial_buff, buff_size)) { + DEBUG_MSG("Warning: invalid GGA sentence (bad checksum)\n"); + return INVALID; + } + nb_fields = str_chop(serial_buff, buff_size, ',', str_index, ARRAY_SIZE(str_index)); + if (nb_fields != 15) { + DEBUG_MSG("Warning: invalid GGA sentence (number of fields)\n"); + return INVALID; + } + /* parse number of satellites used for fix */ + sscanf(serial_buff + str_index[7], "%hd", &gps_sat); + /* parse 3D coordinates */ + i = sscanf(serial_buff + str_index[2], "%2hd%10lf", &gps_dla, &gps_mla); + gps_ola = *(serial_buff + str_index[3]); + j = sscanf(serial_buff + str_index[4], "%3hd%10lf", &gps_dlo, &gps_mlo); + gps_olo = *(serial_buff + str_index[5]); + k = sscanf(serial_buff + 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 INVALID; + } +} + +/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ + +int lgw_gps_get(struct timespec *utc, struct coord_s *loc, struct coord_s *err) { + struct tm x; + time_t y; + + 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); + 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 (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) { + 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 = (count_us - ref->count_us) / TS_CPS; /* uncorrected by xtal_err */ + utc_diff = (utc.tv_sec - (ref->utc).tv_sec) + 1E-9 * (utc.tv_nsec - (ref->utc).tv_nsec); + if (utc_diff == 0.0) { // prevent divide by zero + DEBUG_MSG("ERROR: ATTEMPT TO DIVIDE BY ZERO\n"); + return LGW_GPS_ERROR; + } + + /* detect aberrant points by measuring if slope limits are exceeded */ + 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; + } + + /* 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 = utc; + ref->xtal_err = (0.9 * ref->xtal_err) + (0.1 * slope); /* 10% smoothing factor */ + 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 = utc; + /* 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; +} + +/* --- EOF ------------------------------------------------------------------ */ |