ardupilot/libraries/AP_WheelEncoder/WheelEncoder_Quadrature.h

60 lines
2.2 KiB
C++

/*
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_WheelEncoder.h"
#include "WheelEncoder_Backend.h"
#include <Filter/Filter.h>
#include <AP_Math/AP_Math.h>
class AP_WheelEncoder_Quadrature : public AP_WheelEncoder_Backend
{
public:
// constructor
AP_WheelEncoder_Quadrature(AP_WheelEncoder &frontend, uint8_t instance, AP_WheelEncoder::WheelEncoder_State &state);
// update state
void update(void);
private:
// check if pin has changed and initialise gpio event callback
void update_pin(uint8_t &pin, uint8_t new_pin, uint8_t &pin_value);
// gpio interrupt handlers
void irq_handler(uint8_t pin, bool pin_value, uint32_t timestamp); // combined irq handler
// convert pin a and b status to phase
static uint8_t pin_ab_to_phase(bool pin_a, bool pin_b);
// update phase, distance_count and error count using pin a and b's latest state
void update_phase_and_error_count();
struct IrqState {
uint8_t phase; // current phase of encoder (from 0 to 3)
int32_t distance_count; // distance measured by cumulative steps forward or backwards since last update
uint32_t total_count; // total number of successful readings from sensor (used for sensor quality calcs)
uint32_t error_count; // total number of errors reading from sensor (used for sensor quality calcs)
uint32_t last_reading_ms; // system time of last update from encoder
} irq_state;
// private members
uint8_t last_pin_a = -1;
uint8_t last_pin_b = -1;
uint8_t last_pin_a_value;
uint8_t last_pin_b_value;
};