ardupilot/libraries/AP_GPS/AP_GPS_NMEA.h

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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//
// NMEA parser, adapted by Michael Smith from TinyGPS v9:
//
// TinyGPS - a small GPS library for Arduino providing basic NMEA parsing
// Copyright (C) 2008-9 Mikal Hart
// All rights reserved.
//
//
/// @file AP_GPS_NMEA.h
/// @brief NMEA protocol parser
///
/// This is a lightweight NMEA parser, derived originally from the
/// TinyGPS parser by Mikal Hart. It is frugal in its use of memory
/// and tries to avoid unnecessary arithmetic.
///
/// The parser handles GPGGA, GPRMC and GPVTG messages, and attempts to be
/// robust in the face of occasional corruption in the input stream. It
/// makes a basic effort to configure GPS' that are likely to be connected in
/// NMEA mode (SiRF, MediaTek and ublox) to emit the correct message
/// stream, but does not validate that the correct stream is being received.
/// In particular, a unit emitting just GPRMC will show as having a fix
/// even though no altitude data is being received.
///
/// GPVTG data is parsed, but as the message may not contain the the
/// qualifier field (this is common with e.g. older SiRF units) it is
/// not considered a source of fix-valid information.
///
#pragma once
#include "AP_GPS.h"
#include "GPS_Backend.h"
#if AP_GPS_NMEA_ENABLED
/// NMEA parser
///
class AP_GPS_NMEA : public AP_GPS_Backend
{
friend class AP_GPS_NMEA_Test;
public:
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using AP_GPS_Backend::AP_GPS_Backend;
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/// Checks the serial receive buffer for characters,
/// attempts to parse NMEA data and updates internal state
/// accordingly.
bool read() override;
static bool _detect(struct NMEA_detect_state &state, uint8_t data);
const char *name() const override { return "NMEA"; }
// driver specific health, returns true if the driver is healthy
bool is_healthy(void) const override;
// get lag in seconds
bool get_lag(float &lag_sec) const override;
void Write_AP_Logger_Log_Startup_messages() const override;
private:
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/// Coding for the GPS sentences that the parser handles
enum _sentence_types : uint16_t { //there are some more than 10 fields in some sentences , thus we have to increase these value.
_GPS_SENTENCE_RMC = 32,
_GPS_SENTENCE_GGA = 64,
_GPS_SENTENCE_VTG = 96,
_GPS_SENTENCE_HDT = 128,
_GPS_SENTENCE_PHD = 138, // extension for AllyStar GPS modules
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_GPS_SENTENCE_THS = 160, // True heading with quality indicator, available on Trimble MB-Two
_GPS_SENTENCE_KSXT = 170, // extension for Unicore, 21 fields
_GPS_SENTENCE_AGRICA = 193, // extension for Unicore, 65 fields
_GPS_SENTENCE_VERSIONA = 270, // extension for Unicore, version, 10 fields
_GPS_SENTENCE_UNIHEADINGA = 290, // extension for Unicore, uniheadinga, 20 fields
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_GPS_SENTENCE_OTHER = 0
};
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/// Update the decode state machine with a new character
///
/// @param c The next character in the NMEA input stream
/// @returns True if processing the character has resulted in
/// an update to the GPS state
///
bool _decode(char c);
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/// Parses the @p as a NMEA-style decimal number with
/// up to 3 decimal digits.
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///
/// @returns The value expressed by the string in @p,
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/// multiplied by 100.
///
static int32_t _parse_decimal_100(const char *p);
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/// Parses the current term as a NMEA-style degrees + minutes
/// value with up to four decimal digits.
///
/// This gives a theoretical resolution limit of around 1cm.
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///
/// @returns The value expressed by the string in _term,
/// multiplied by 1e7.
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///
uint32_t _parse_degrees();
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/// Processes the current term when it has been deemed to be
/// complete.
///
/// Each GPS message is broken up into terms separated by commas.
/// Each term is then processed by this function as it is received.
///
/// @returns True if completing the term has resulted in
/// an update to the GPS state.
bool _term_complete();
/// return true if we have a new set of NMEA messages
bool _have_new_message(void);
#if AP_GPS_NMEA_UNICORE_ENABLED
/*
parse an AGRICA field
*/
void parse_agrica_field(uint16_t term_number, const char *term);
// parse VERSIONA field
void parse_versiona_field(uint16_t term_number, const char *term);
#if GPS_MOVING_BASELINE
// parse UNIHEADINGA field
void parse_uniheadinga_field(uint16_t term_number, const char *term);
#endif
#endif
uint8_t _parity; ///< NMEA message checksum accumulator
uint32_t _crc32; ///< CRC for unicore messages
bool _is_checksum_term; ///< current term is the checksum
char _term[30]; ///< buffer for the current term within the current sentence
uint16_t _sentence_type; ///< the sentence type currently being processed
bool _is_unicore; ///< true if in a unicore '#' sentence
uint16_t _term_number; ///< term index within the current sentence
uint8_t _term_offset; ///< character offset with the term being received
uint16_t _sentence_length;
bool _sentence_done; ///< set when a sentence has been fully decoded
// The result of parsing terms within a message is stored temporarily until
// the message is completely processed and the checksum validated.
// This avoids the need to buffer the entire message.
int32_t _new_time; ///< time parsed from a term
int32_t _new_date; ///< date parsed from a term
int32_t _new_latitude; ///< latitude parsed from a term
int32_t _new_longitude; ///< longitude parsed from a term
int32_t _new_altitude; ///< altitude parsed from a term
int32_t _new_speed; ///< speed parsed from a term
int32_t _new_course; ///< course parsed from a term
float _new_gps_yaw; ///< yaw parsed from a term
uint16_t _new_hdop; ///< HDOP parsed from a term
uint8_t _new_satellite_count; ///< satellite count parsed from a term
uint8_t _new_quality_indicator; ///< GPS quality indicator parsed from a term
uint32_t _last_RMC_ms;
uint32_t _last_GGA_ms;
uint32_t _last_VTG_ms;
uint32_t _last_yaw_ms;
uint32_t _last_vvelocity_ms;
uint32_t _last_vaccuracy_ms;
uint32_t _last_3D_velocity_ms;
uint32_t _last_KSXT_pos_ms;
uint32_t _last_AGRICA_ms;
uint32_t _last_fix_ms;
/// @name Init strings
/// In ::init, an attempt is made to configure the GPS
/// unit to send just the messages that we are interested
/// in using these strings
//@{
static const char _SiRF_init_string[]; ///< init string for SiRF units
static const char _ublox_init_string[]; ///< init string for ublox units
//@}
static const char _initialisation_blob[];
/*
the $PHD message is an extension from AllyStar that gives
vertical velocity and more accuracy estimates. It is designed as
a mapping from ublox UBX protocol messages to NMEA. So class 1,
message 12 is a mapping to NMEA of the NAV-VELNED UBX message
and contains the same fields. Class 1 message 26 is called
"NAV-PVERR", but does not correspond to a UBX message
example:
$PHD,01,12,TIIITTITT,,245808000,0,0,0,0,0,10260304,0,0*27
$PHD,01,26,TTTTTTT,,245808000,877,864,1451,11,11,17*17
*/
struct {
uint8_t msg_class;
uint8_t msg_id;
uint32_t itow;
int32_t fields[8];
} _phd;
/*
The KSXT message is an extension from Unicore that gives 3D velocity and yaw
example: $KSXT,20211016083433.00,116.31296102,39.95817066,49.4911,223.57,-11.32,330.19,0.024,,1,3,28,27,,,,-0.012,0.021,0.020,,*2D
*/
struct {
double fields[21];
} _ksxt;
#if AP_GPS_NMEA_UNICORE_ENABLED
/*
unicore AGRICA message parsing
*/
struct {
uint32_t start_byte;
uint8_t rtk_status;
uint8_t heading_status;
Vector3f vel_NED;
Vector3f vel_stddev;
double lat, lng;
float alt;
uint32_t itow;
float undulation;
Vector3f pos_stddev;
} _agrica;
// unicore VERSIONA parsing
struct {
char type[10];
char version[20];
char build_date[13];
} _versiona;
bool _have_unicore_versiona;
#if GPS_MOVING_BASELINE
// unicore UNIHEADINGA parsing
struct {
float baseline_length;
float heading;
float pitch;
float heading_sd;
} _uniheadinga;
#endif
#endif // AP_GPS_NMEA_UNICORE_ENABLED
bool _expect_agrica;
// last time we sent type specific config strings
uint32_t last_config_ms;
// send type specific config strings
void send_config(void);
};
#if AP_GPS_NMEA_UNICORE_ENABLED && !defined(NMEA_UNICORE_SETUP)
// we don't know what port the GPS may be using, so configure all 3. We need to get it sending
// one message to allow the NMEA detector to run
#define NMEA_UNICORE_SETUP "CONFIG COM1 230400 8 n 1\r\nCONFIG COM2 230400 8 n 1\r\nCONFIG COM3 230400 8 n 1\r\nGPGGA 0.2\r\n"
#endif
#endif // AP_GPS_NMEA_ENABLED