ardupilot/libraries/AP_Camera/AP_Camera_Backend.cpp

#include "AP_Camera_Backend.h"

#if AP_CAMERA_ENABLED
#include <GCS_MAVLink/GCS.h>
#include <AP_GPS/AP_GPS.h>

extern const AP_HAL::HAL& hal;

// Constructor
AP_Camera_Backend::AP_Camera_Backend(AP_Camera &frontend, AP_Camera_Params &params, uint8_t instance) :
    _frontend(frontend),
    _params(params),
    _instance(instance)
{}

// update - should be called at 50hz
void AP_Camera_Backend::update()
{
    // try to take picture if pending
    if (trigger_pending) {
        take_picture();
    }

    // check feedback pin
    check_feedback();

    // implement trigger distance
    if (!is_positive(_params.trigg_dist)) {
        last_location.lat = 0;
        last_location.lng = 0;
        return;
    }

    // check GPS status
    if (AP::gps().status() < AP_GPS::GPS_OK_FIX_3D) {
        return;
    }

    // check vehicle flight mode supports trigg dist
    if (!_frontend.vehicle_mode_ok_for_trigg_dist()) {
        return;
    }

    // check vehicle roll angle is less than configured maximum
    const AP_AHRS &ahrs = AP::ahrs();
    if ((_frontend.get_roll_max() > 0) && (fabsf(AP::ahrs().roll_sensor * 1e-2f) > _frontend.get_roll_max())) {
        return;
    }

    // get current location. ignore failure because AHRS will provide its best guess
    Location current_loc;
    IGNORE_RETURN(ahrs.get_location(current_loc));

    // initialise last location to current location
    if (last_location.lat == 0 && last_location.lng == 0) {
        last_location = current_loc;
        return;
    }
    if (last_location.lat == current_loc.lat && last_location.lng == current_loc.lng) {
        // we haven't moved - this can happen as update() may
        // be called without a new GPS fix
        return;
    }

    // check vehicle has moved at least trigg_dist meters
    if (current_loc.get_distance(last_location) < _params.trigg_dist) {
        return;
    }

    take_picture();
}

// take a picture.  returns true on success
bool AP_Camera_Backend::take_picture()
{
    // setup feedback pin interrupt or timer
    setup_feedback_callback();

    // check minimum time interval since last picture taken
    uint32_t now_ms = AP_HAL::millis();
    if (now_ms - last_photo_time_ms < (uint32_t)(_params.interval_min * 1000)) {
        trigger_pending = true;
        return false;
    }

    trigger_pending = false;

    // trigger actually taking picture and update image count
    if (trigger_pic()) {
        image_index++;
        last_photo_time_ms = now_ms;
        IGNORE_RETURN(AP::ahrs().get_location(last_location));
        log_picture();
        return true;
    }

    return false;
}

// handle camera control
void AP_Camera_Backend::control(float session, float zoom_pos, float zoom_step, float focus_lock, float shooting_cmd, float cmd_id)
{
    // take picture
    if (is_equal(shooting_cmd, 1.0f)) {
        take_picture();
    }
}

// send camera feedback message to GCS
void AP_Camera_Backend::send_camera_feedback(mavlink_channel_t chan)
{
    int32_t altitude = 0;
    if (camera_feedback.location.initialised() && !camera_feedback.location.get_alt_cm(Location::AltFrame::ABSOLUTE, altitude)) {
        // completely ignore this failure!  this is a shouldn't-happen
        // as current_loc should never be in an altitude we can't
        // convert.
    }
    int32_t altitude_rel = 0;
    if (camera_feedback.location.initialised() && !camera_feedback.location.get_alt_cm(Location::AltFrame::ABOVE_HOME, altitude_rel)) {
        // completely ignore this failure!  this is a shouldn't-happen
        // as current_loc should never be in an altitude we can't
        // convert.
    }

    // send camera feedback message
    mavlink_msg_camera_feedback_send(
        chan,
        camera_feedback.timestamp_us,       // image timestamp
        0,                                  // target system id
        _instance,                          // camera id
        image_index,                        // image index
        camera_feedback.location.lat,       // latitude
        camera_feedback.location.lng,       // longitude
        altitude*1e-2f,                     // alt MSL
        altitude_rel*1e-2f,                 // alt relative to home
        camera_feedback.roll_sensor*1e-2f,  // roll angle (deg)
        camera_feedback.pitch_sensor*1e-2f, // pitch angle (deg)
        camera_feedback.yaw_sensor*1e-2f,   // yaw angle (deg)
        0.0f,                               // focal length
        CAMERA_FEEDBACK_PHOTO,              // flags
        camera_feedback.feedback_trigger_logged_count); // completed image captures
}

// setup a callback for a feedback pin. When on PX4 with the right FMU
// mode we can use the microsecond timer.
void AP_Camera_Backend::setup_feedback_callback()
{
    if (_params.feedback_pin <= 0 || timer_installed || isr_installed) {
        // invalid or already installed
        return;
    }

    // ensure we are in input mode
    hal.gpio->pinMode(_params.feedback_pin, HAL_GPIO_INPUT);

    // enable pullup/pulldown
    uint8_t trigger_polarity = _params.feedback_polarity == 0 ? 0 : 1;
    hal.gpio->write(_params.feedback_pin, !trigger_polarity);

    if (hal.gpio->attach_interrupt(_params.feedback_pin, FUNCTOR_BIND_MEMBER(&AP_Camera_Backend::feedback_pin_isr, void, uint8_t, bool, uint32_t),
                                   trigger_polarity?AP_HAL::GPIO::INTERRUPT_RISING:AP_HAL::GPIO::INTERRUPT_FALLING)) {
        isr_installed = true;
    } else {
        // install a 1kHz timer to check feedback pin
        hal.scheduler->register_timer_process(FUNCTOR_BIND_MEMBER(&AP_Camera_Backend::feedback_pin_timer, void));

        timer_installed = true;
    }
}

// interrupt handler for interrupt based feedback trigger
void AP_Camera_Backend::feedback_pin_isr(uint8_t pin, bool high, uint32_t timestamp_us)
{
    feedback_trigger_timestamp_us = timestamp_us;
    feedback_trigger_count++;
}

// check if feedback pin is high for timer based feedback trigger, when
// attach_interrupt fails
void AP_Camera_Backend::feedback_pin_timer()
{
    uint8_t pin_state = hal.gpio->read(_params.feedback_pin);
    uint8_t trigger_polarity = _params.feedback_polarity == 0 ? 0 : 1;
    if (pin_state == trigger_polarity &&
        last_pin_state != trigger_polarity) {
        feedback_trigger_timestamp_us = AP_HAL::micros();
        feedback_trigger_count++;
    }
    last_pin_state = pin_state;
}

// check for feedback pin update and log if necessary
void AP_Camera_Backend::check_feedback()
{
    if (feedback_trigger_logged_count != feedback_trigger_count) {
        const uint32_t timestamp32 = feedback_trigger_timestamp_us;
        feedback_trigger_logged_count = feedback_trigger_count;

        // we should consider doing this inside the ISR and pin_timer
        prep_mavlink_msg_camera_feedback(feedback_trigger_timestamp_us);

        // log camera message
        uint32_t tdiff = AP_HAL::micros() - timestamp32;
        uint64_t timestamp = AP_HAL::micros64();
        Write_Camera(timestamp - tdiff);
    }
}

void AP_Camera_Backend::prep_mavlink_msg_camera_feedback(uint64_t timestamp_us)
{
    const AP_AHRS &ahrs = AP::ahrs();
    if (!ahrs.get_location(camera_feedback.location)) {
        // completely ignore this failure!  AHRS will provide its best guess.
    }
    camera_feedback.timestamp_us = timestamp_us;
    camera_feedback.roll_sensor = ahrs.roll_sensor;
    camera_feedback.pitch_sensor = ahrs.pitch_sensor;
    camera_feedback.yaw_sensor = ahrs.yaw_sensor;
    camera_feedback.feedback_trigger_logged_count = feedback_trigger_logged_count;

    gcs().send_message(MSG_CAMERA_FEEDBACK);
}

// log picture
void AP_Camera_Backend::log_picture()
{
    const bool using_feedback_pin = _params.feedback_pin > 0;

    if (!using_feedback_pin) {
        // if we're using a feedback pin then when the event occurs we
        // stash the feedback data.  Since we're not using a feedback
        // pin, we just use "now".
        prep_mavlink_msg_camera_feedback(AP::gps().time_epoch_usec());
    }

    if (!using_feedback_pin) {
        Write_Camera();
    } else {
        Write_Trigger();
    }
}

#endif // AP_CAMERA_ENABLED