AP_GPS_SIRF.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/>.
 */

//
//  SiRF Binary GPS driver for ArduPilot and ArduPilotMega.
//  Code by Michael Smith.
//
#pragma once

#include <AP_Common/AP_Common.h>
#include <AP_HAL/AP_HAL.h>

#include "AP_GPS.h"
#include "GPS_Backend.h"

#define SIRF_SET_BINARY "$PSRF100,0,38400,8,1,0*3C\r\n"

class AP_GPS_SIRF : public AP_GPS_Backend {
public:
    AP_GPS_SIRF(AP_GPS &_gps, AP_GPS::GPS_State &_state, AP_HAL::UARTDriver *_port);

    bool read();

    static bool _detect(struct SIRF_detect_state &state, uint8_t data);

    const char *name() const override { return "SIRF"; }

private:
    struct PACKED sirf_geonav {
        uint16_t fix_invalid;
        uint16_t fix_type;
        uint16_t week;
        uint32_t time;
        uint16_t year;
        uint8_t month;
        uint8_t day;
        uint8_t hour;
        uint8_t minute;
        uint16_t second;
        uint32_t satellites_used;
        int32_t latitude;
        int32_t longitude;
        int32_t altitude_ellipsoid;
        int32_t altitude_msl;
        int8_t map_datum;
        int16_t ground_speed;
        int16_t ground_course;
        int16_t res1;
        int16_t climb_rate;
        uint16_t heading_rate;
        uint32_t horizontal_position_error;
        uint32_t vertical_position_error;
        uint32_t time_error;
        int16_t horizontal_velocity_error;
        int32_t clock_bias;
        uint32_t clock_bias_error;
        int32_t clock_drift;
        uint32_t clock_drift_error;
        uint32_t distance;
        uint16_t distance_error;
        uint16_t heading_error;
        uint8_t satellites;
        uint8_t hdop;
        uint8_t mode_info;
    };
    enum sirf_protocol_bytes {
        PREAMBLE1 = 0xa0,
        PREAMBLE2 = 0xa2,
        POSTAMBLE1 = 0xb0,
        POSTAMBLE2 = 0xb3,
        MSG_GEONAV = 0x29
    };
    enum sirf_fix_type {
        FIX_3D = 0x6,
        FIX_MASK = 0x7
    };


    // State machine state
    uint8_t         _step;
    uint16_t        _checksum;
    bool            _gather;
    uint16_t        _payload_length;
    uint16_t        _payload_counter;
    uint8_t         _msg_id;

    // Message buffer
    union {
        DEFINE_BYTE_ARRAY_METHODS
        sirf_geonav nav;
    } _buffer;

    bool        _parse_gps(void);
    void        _accumulate(uint8_t val);

    static const uint8_t _initialisation_blob[];
};