ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_Bebop.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/>.
*/
#pragma once
#include "AP_RangeFinder.h"
#include "AP_RangeFinder_Backend.h"
#include <AP_HAL_Linux/Thread.h>
/*
* the size of the buffer sent over spi
*/
#define RNFD_BEBOP_NB_PULSES_MAX 32
/*
* the size of the purge buffer sent over spi
*/
#define RNFD_BEBOP_NB_PULSES_PURGE 64
/*
* default us frequency
* 17 times by seconds
*/
#define RNFD_BEBOP_DEFAULT_FREQ 17
/*
* default adc frequency
*/
#define RNFD_BEBOP_DEFAULT_ADC_FREQ 160000
/*
* to filter data we make the average of (1 << this_value) datas
*/
#define RNFD_BEBOP_FILTER_POWER 2
/*
* Speed of sound
*/
#define RNFD_BEBOP_SOUND_SPEED 340
/* above this altitude we should use mode 0 */
#define RNFD_BEBOP_TRANSITION_HIGH_TO_LOW 0.75
/* below this altitude we should use mode 1 */
#define RNFD_BEBOP_TRANSITION_LOW_TO_HIGH 1.5
/* count this times before switching mode */
#define RNFD_BEBOP_TRANSITION_COUNT 5
/*
* the number of echoes we will keep at most
*/
#define RNFD_BEBOP_MAX_ECHOES 30
struct echo {
int max_index; /* index in the capture buffer at which the maximum is reached */
int distance_index; /* index in the capture buffer at which the signal is for
the first time above a fixed threshold below the
maximum => this corresponds to the real distance
that should be attributed to this echo */
};
/*
* struct related to adc
* data to receive and process adc datas
*/
struct adc_capture {
struct iio_device *device;
struct iio_buffer *buffer;
unsigned int buffer_size;
struct iio_channel *channel;
unsigned int freq;
/* Used in order to match two echoes of two ADC acquisitions */
unsigned short threshold_time_rejection;
};
class AP_RangeFinder_Bebop : public AP_RangeFinder_Backend {
public:
AP_RangeFinder_Bebop(RangeFinder::RangeFinder_State &_state, AP_RangeFinder_Params &_params);
~AP_RangeFinder_Bebop(void);
static bool detect();
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void update(void) override;
protected:
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MAV_DISTANCE_SENSOR _get_mav_distance_sensor_type() const override {
return MAV_DISTANCE_SENSOR_LASER;
}
private:
void _init(void);
int _launch(void);
int _capture(void);
int _update_mode(float altitude);
void _configure_gpio(int value);
int _configure_wave();
void _reconfigure_wave();
int _configure_capture();
int _launch_purge();
void _loop(void);
Linux::Thread *_thread;
unsigned short get_threshold_at(int i_capture);
int _apply_averaging_filter(void);
int _search_local_maxima(void);
int _search_maximum_with_max_amplitude(void);
AP_HAL::OwnPtr<AP_HAL::Device> _spi;
AP_HAL::GPIO *_gpio;
struct adc_capture _adc;
struct iio_context *_iio;
unsigned char _tx[2][RNFD_BEBOP_NB_PULSES_MAX];
unsigned char _purge[RNFD_BEBOP_NB_PULSES_PURGE];
unsigned char* _tx_buf;
int _hysteresis_counter;
const unsigned int threshold_echo_init = 1500;
int _fd = -1;
uint64_t _last_timestamp;
int _mode;
int _nb_echoes;
int _freq;
float _altitude;
unsigned int *_filtered_capture;
unsigned int _filtered_capture_size;
struct echo _echoes[RNFD_BEBOP_MAX_ECHOES];
unsigned int _filter_average = 4;
int16_t _last_max_distance_cm = 850;
int16_t _last_min_distance_cm = 32;
};