234 lines
9.5 KiB
C
234 lines
9.5 KiB
C
/*
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/ _____) _ | |
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( (____ _____ ____ _| |_ _____ ____| |__
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\____ \| ___ | (_ _) ___ |/ ___) _ \
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_____) ) ____| | | || |_| ____( (___| | | |
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(______/|_____)_|_|_| \__)_____)\____)_| |_|
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(C)2019 Semtech
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Description:
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Library of functions to manage a GNSS module (typically GPS) for accurate
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timestamping of packets and synchronisation of gateways.
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A limited set of module brands/models are supported.
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License: Revised BSD License, see LICENSE.TXT file include in the project
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*/
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#ifndef _LORAGW_GPS_H
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#define _LORAGW_GPS_H
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/* -------------------------------------------------------------------------- */
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/* --- DEPENDANCIES --------------------------------------------------------- */
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#define _GNU_SOURCE
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#include <stdint.h> /* C99 types */
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#include <time.h> /* time library */
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#include <termios.h> /* speed_t */
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#include <unistd.h> /* ssize_t */
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#include "config.h" /* library configuration options (dynamically generated) */
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/* -------------------------------------------------------------------------- */
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/* --- PUBLIC TYPES --------------------------------------------------------- */
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/**
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@struct coord_s
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@brief Time solution required for timestamp to absolute time conversion
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*/
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struct tref {
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time_t systime; /*!> system time when solution was calculated */
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uint32_t count_us; /*!> reference concentrator internal timestamp */
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struct timespec utc; /*!> reference UTC time (from GPS/NMEA) */
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struct timespec gps; /*!> reference GPS time (since 01.Jan.1980) */
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double xtal_err; /*!> raw clock error (eg. <1 'slow' XTAL) */
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};
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/**
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@struct coord_s
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@brief Geodesic coordinates
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*/
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struct coord_s {
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double lat; /*!> latitude [-90,90] (North +, South -) */
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double lon; /*!> longitude [-180,180] (East +, West -)*/
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short alt; /*!> altitude in meters (WGS 84 geoid ref.) */
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};
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/**
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@enum gps_msg
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@brief Type of GPS (and other GNSS) sentences
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*/
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enum gps_msg {
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UNKNOWN, /*!> neutral value */
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IGNORED, /*!> frame was not parsed by the system */
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INVALID, /*!> system try to parse frame but failed */
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INCOMPLETE, /*!> frame parsed was missing bytes */
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/* NMEA messages of interest */
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NMEA_RMC, /*!> Recommended Minimum data (time + date) */
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NMEA_GGA, /*!> Global positioning system fix data (pos + alt) */
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NMEA_GNS, /*!> GNSS fix data (pos + alt, sat number) */
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NMEA_ZDA, /*!> Time and Date */
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/* NMEA message useful for time reference quality assessment */
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NMEA_GBS, /*!> GNSS Satellite Fault Detection */
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NMEA_GST, /*!> GNSS Pseudo Range Error Statistics */
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NMEA_GSA, /*!> GNSS DOP and Active Satellites (sat number) */
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NMEA_GSV, /*!> GNSS Satellites in View (sat SNR) */
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/* Misc. NMEA messages */
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NMEA_GLL, /*!> Latitude and longitude, with time fix and status */
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NMEA_TXT, /*!> Text Transmission */
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NMEA_VTG, /*!> Course over ground and Ground speed */
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/* uBlox proprietary NMEA messages of interest */
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UBX_NAV_TIMEGPS, /*!> GPS Time Solution */
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UBX_NAV_TIMEUTC /*!> UTC Time Solution */
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};
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/* -------------------------------------------------------------------------- */
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/* --- PUBLIC CONSTANTS ----------------------------------------------------- */
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#define LGW_GPS_SUCCESS 0
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#define LGW_GPS_ERROR -1
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#define LGW_GPS_MIN_MSG_SIZE (8)
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#define LGW_GPS_UBX_SYNC_CHAR (0xB5)
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#define LGW_GPS_NMEA_SYNC_CHAR (0x24)
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/* -------------------------------------------------------------------------- */
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/* --- PUBLIC FUNCTIONS PROTOTYPES ------------------------------------------ */
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/**
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@brief Configure a GPS module
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@param tty_path path to the TTY connected to the GPS
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@param gps_familly parameter (eg. ubx6 for uBlox gen.6)
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@param target_brate target baudrate for communication (0 keeps default target baudrate)
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@param fd_ptr pointer to a variable to receive file descriptor on GPS tty
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@return success if the function was able to connect and configure a GPS module
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*/
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int lgw_gps_enable(char* tty_path, char* gps_familly, speed_t target_brate, int* fd_ptr);
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/**
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@brief Restore GPS serial configuration and close serial device
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@param fd file descriptor on GPS tty
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@return success if the function was able to complete
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*/
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int lgw_gps_disable(int fd);
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/**
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@brief Parse messages coming from the GPS system (or other GNSS)
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@param serial_buff pointer to the string to be parsed
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@param buff_size maximum string lengths for NMEA parsing (incl. null char)
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@return type of frame parsed
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The RAW NMEA sentences are parsed to a global set of variables shared with the
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lgw_gps_get function.
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If the lgw_parse_nmea and lgw_gps_get are used in different threads, a mutex
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lock must be acquired before calling either function.
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*/
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enum gps_msg lgw_parse_nmea(const char* serial_buff, int buff_size);
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/**
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@brief Parse Ublox proprietary messages coming from the GPS system
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@param serial_buff pointer to the string to be parsed
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@param buff_size maximum string lengths for UBX parsing (incl. null char)
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@param msg_size number of bytes parsed as UBX message if found
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@return type of frame parsed
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The RAW UBX sentences are parsed to a global set of variables shared with the
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lgw_gps_get function.
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If the lgw_parse_ubx and lgw_gps_get are used in different threads, a mutex
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lock must be acquired before calling either function.
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*/
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enum gps_msg lgw_parse_ubx(const char* serial_buff, size_t buff_size, size_t *msg_size);
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/**
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@brief Get the GPS solution (space & time) for the concentrator
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@param utc pointer to store UTC time, with ns precision (NULL to ignore)
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@param gps_time pointer to store GPS time, with ns precision (NULL to ignore)
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@param loc pointer to store coordinates (NULL to ignore)
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@param err pointer to store coordinates standard deviation (NULL to ignore)
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@return success if the chosen elements could be returned
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This function read the global variables generated by the NMEA/UBX parsing
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functions lgw_parse_nmea/lgw_parse_ubx. It returns time and location data in a
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format that is exploitable by other functions in that library sub-module.
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If the lgw_parse_nmea/lgw_parse_ubx and lgw_gps_get are used in different
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threads, a mutex lock must be acquired before calling either function.
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*/
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int lgw_gps_get(struct timespec *utc, struct timespec *gps_time, struct coord_s *loc, struct coord_s *err);
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/**
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@brief Get time and position information from the serial GPS last message received
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@param utc UTC time, with ns precision (leap seconds are ignored)
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@param gps_time timestamp of last time pulse from the GPS module converted to the UNIX epoch
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(leap seconds are ignored)
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@param loc location information
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@param err location error estimate if supported
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@return success if timestamp was read and time reference could be refreshed
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Set systime to 0 in ref to trigger initial synchronization.
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*/
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int lgw_gps_sync(struct tref *ref, uint32_t count_us, struct timespec utc, struct timespec gps_time);
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/**
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@brief Convert concentrator timestamp counter value to UTC time
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@param ref time reference structure required for time conversion
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@param count_us internal timestamp counter of the LoRa concentrator
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@param utc pointer to store UTC time, with ns precision (leap seconds ignored)
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@return success if the function was able to convert timestamp to UTC
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This function is typically used when a packet is received to transform the
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internal counter-based timestamp in an absolute timestamp with an accuracy in
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the order of a couple microseconds (ns resolution).
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*/
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int lgw_cnt2utc(struct tref ref, uint32_t count_us, struct timespec* utc);
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/**
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@brief Convert UTC time to concentrator timestamp counter value
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@param ref time reference structure required for time conversion
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@param utc UTC time, with ns precision (leap seconds are ignored)
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@param count_us pointer to store internal timestamp counter of LoRa concentrator
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@return success if the function was able to convert UTC to timestamp
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This function is typically used when a packet must be sent at an accurate time
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(eg. to send a piggy-back response after receiving a packet from a node) to
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transform an absolute UTC time into a matching internal concentrator timestamp.
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*/
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int lgw_utc2cnt(struct tref ref,struct timespec utc, uint32_t* count_us);
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/**
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@brief Convert concentrator timestamp counter value to GPS time
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@param ref time reference structure required for time conversion
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@param count_us internal timestamp counter of the LoRa concentrator
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@param gps_time pointer to store GPS time, with ns precision (leap seconds ignored)
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@return success if the function was able to convert timestamp to GPS time
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This function is typically used when a packet is received to transform the
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internal counter-based timestamp in an absolute timestamp with an accuracy in
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the order of a millisecond.
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*/
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int lgw_cnt2gps(struct tref ref, uint32_t count_us, struct timespec* gps_time);
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/**
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@brief Convert GPS time to concentrator timestamp counter value
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@param ref time reference structure required for time conversion
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@param gps_time GPS time, with ns precision (leap seconds are ignored)
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@param count_us pointer to store internal timestamp counter of LoRa concentrator
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@return success if the function was able to convert GPS time to timestamp
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This function is typically used when a packet must be sent at an accurate time
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(eg. to send a piggy-back response after receiving a packet from a node) to
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transform an absolute GPS time into a matching internal concentrator timestamp.
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*/
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int lgw_gps2cnt(struct tref ref, struct timespec gps_time, uint32_t* count_us);
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#endif
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/* --- EOF ------------------------------------------------------------------ */
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