ardupilot/libraries/AP_HAL_ChibiOS/SoftSigReader.h

/*
 * This file 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 file 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/>.
 * 
 * Code by Andrew Tridgell and Siddharth Bharat Purohit
 */
#pragma once
#include <AP_HAL/utility/RingBuffer.h>
#include <AP_HAL/AP_HAL_Boards.h>

#include "AP_HAL_ChibiOS.h"

#if HAL_USE_ICU == TRUE

#define INPUT_CAPTURE_FREQUENCY 1000000 //capture unit in microseconds
#define MAX_SIGNAL_TRANSITIONS 256
#define DEFAULT_BOUNCE_BUF_SIZE 32

class ChibiOS::SoftSigReader {
public:
    bool attach_capture_timer(ICUDriver* icu_drv, icuchannel_t chan, uint8_t dma_stream, uint32_t dma_channel);
    bool read(uint32_t &widths0, uint32_t &widths1);
    //This sets the size of bounce buffer size, which in turn controls the rate of interrupt from DMA
    bool set_bounce_buf_size(uint16_t buf_size);
private:
    uint32_t *signal;
    static void _irq_handler(void* self, uint32_t flags);
    uint8_t num_timer_channels;
    ObjectBuffer<uint32_t> sigbuf{MAX_SIGNAL_TRANSITIONS};
    uint8_t enable_chan_mask;
    uint8_t max_pulse_width;
    const stm32_dma_stream_t* dma;
    ICUConfig icucfg;
    ICUDriver* _icu_drv = nullptr;
    uint16_t _bounce_buf_size = DEFAULT_BOUNCE_BUF_SIZE;
    bool need_swap;
};

#endif // HAL_USE_ICU