ardupilot/libraries/AP_ExternalAHRS/MicroStrain_common.h

/*
   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/>.
 */
/*
  suppport for MicroStrain MIP parsing
 */

#pragma once

#include "AP_ExternalAHRS_config.h"

#if AP_MICROSTRAIN_ENABLED

#include <AP_GPS/AP_GPS.h>
#include <AP_Math/vector3.h>
#include <AP_Math/quaternion.h>

class AP_MicroStrain
{
public:


protected:

    enum class ParseState {
        WaitingFor_SyncOne,
        WaitingFor_SyncTwo,
        WaitingFor_Descriptor,
        WaitingFor_PayloadLength,
        WaitingFor_Data,
        WaitingFor_Checksum
    };

        // A MicroStrain packet can be a maximum of 261 bytes
    struct MicroStrain_Packet {
        uint8_t header[4];
        uint8_t payload[255];
        uint8_t checksum[2];
    };

    struct {
        MicroStrain_Packet packet;
        AP_MicroStrain::ParseState state;
        uint8_t index;
    } message_in;

    struct {
        Vector3f accel;
        Vector3f gyro;
        Vector3f mag;
        Quaternion quat;
        float pressure;
    } imu_data;

    struct {
        uint16_t week;
        uint32_t tow_ms;
        GPS_FIX_TYPE fix_type;
        uint8_t satellites;
        float horizontal_position_accuracy;
        float vertical_position_accuracy;
        float hdop;
        float vdop;
        int32_t lon;
        int32_t lat;
        int32_t msl_altitude;
        float ned_velocity_north;
        float ned_velocity_east;
        float ned_velocity_down;
        float speed_accuracy;
    } gnss_data;

    struct {
        uint16_t state;
        uint16_t mode;
        uint16_t flags;
    } filter_status;

    struct {
        uint16_t week;
        uint32_t tow_ms;
        float horizontal_position_accuracy;
        float vertical_position_accuracy;
        int32_t lon;
        int32_t lat;
        int32_t hae_altitude;
        float ned_velocity_north;
        float ned_velocity_east;
        float ned_velocity_down;
        float speed_accuracy;
    } filter_data;

    enum class DescriptorSet {
        BaseCommand = 0x01,
        DMCommand = 0x0C,
        SystemCommand = 0x7F,
        IMUData = 0x80,
        GNSSData = 0x81,
        EstimationData = 0x82
    };

    const uint8_t SYNC_ONE = 0x75;
    const uint8_t SYNC_TWO = 0x65;

    uint32_t last_ins_pkt;
    uint32_t last_gps_pkt;
    uint32_t last_filter_pkt;

    // Handle a single byte.
    // If the byte matches a descriptor, it returns true and that type should be handled.
    bool handle_byte(const uint8_t b, DescriptorSet& descriptor);
    // Returns true if the fletcher checksum for the packet is valid, else false.
    static bool valid_packet(const MicroStrain_Packet &packet);
    // Calls the correct functions based on the packet descriptor of the packet
    DescriptorSet handle_packet(const MicroStrain_Packet &packet);
    // Collects data from an imu packet into `imu_data`
    void handle_imu(const MicroStrain_Packet &packet);
    // Collects data from a gnss packet into `gnss_data`
    void handle_gnss(const MicroStrain_Packet &packet);
    void handle_filter(const MicroStrain_Packet &packet);
    static Vector3f populate_vector3f(const uint8_t* data, uint8_t offset);
    static Quaternion populate_quaternion(const uint8_t* data, uint8_t offset);
};

#endif // AP_MICROSTRAIN_ENABLED