ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_NMEA.h

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2018-05-14 02:03:08 -03:00
/*
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/>.
*/
#pragma once
#include "RangeFinder.h"
#include "RangeFinder_Backend.h"
class AP_RangeFinder_NMEA : public AP_RangeFinder_Backend
{
public:
// constructor
AP_RangeFinder_NMEA(RangeFinder::RangeFinder_State &_state,
AP_RangeFinder_Params &_params,
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AP_SerialManager &serial_manager,
uint8_t serial_instance);
// static detection function
static bool detect(AP_SerialManager &serial_manager, uint8_t serial_instance);
// update state
void update(void) override;
protected:
virtual MAV_DISTANCE_SENSOR _get_mav_distance_sensor_type() const override {
return MAV_DISTANCE_SENSOR_ULTRASOUND;
}
private:
/// enum for handled messages
enum sentence_types : uint8_t {
SONAR_UNKNOWN = 0,
SONAR_DBT,
SONAR_DPT
};
// get a reading
bool get_reading(uint16_t &reading_cm);
// add a single character to the buffer and attempt to decode
// returns true if a complete sentence was successfully decoded
// distance should be pulled directly from _distance_m member
bool decode(char c);
// decode the just-completed term
// returns true if new sentence has just passed checksum test and is validated
bool decode_latest_term();
// return the numeric value of an ascii hex character
static int16_t char_to_hex(char a);
AP_HAL::UARTDriver *uart = nullptr; // pointer to serial uart
// message decoding related members
char _term[15]; // buffer for the current term within the current sentence
uint8_t _term_offset; // offset within the _term buffer where the next character should be placed
uint8_t _term_number; // term index within the current sentence
float _distance_m; // distance in meters parsed from a term, -1 if no distance
uint8_t _checksum; // checksum accumulator
bool _term_is_checksum; // current term is the checksum
sentence_types _sentence_type; // the sentence type currently being processed
};