esc.cpp

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/**
 * @file esc.cpp
 *
 * @author Pavel Kirienko <pavel.kirienko@gmail.com>
 */

#include "esc.hpp"
#include <systemlib/err.h>
#include <drivers/drv_hrt.h>

#define MOTOR_BIT(x) (1<<(x))

using namespace time_literals;

UavcanEscController::UavcanEscController(uavcan::INode &node) :
    _node(node),
    _uavcan_pub_raw_cmd(node),
    _uavcan_sub_status(node),
    _orb_timer(node)
{
    _uavcan_pub_raw_cmd.setPriority(UAVCAN_COMMAND_TRANSFER_PRIORITY);
}

UavcanEscController::~UavcanEscController()
{
}

int
UavcanEscController::init()
{
    // ESC status subscription
    int res = _uavcan_sub_status.start(StatusCbBinder(this, &UavcanEscController::esc_status_sub_cb));

    if (res < 0) {
        PX4_ERR("ESC status sub failed %i", res);
        return res;
    }

    // ESC status will be relayed from UAVCAN bus into ORB at this rate
    _orb_timer.setCallback(TimerCbBinder(this, &UavcanEscController::orb_pub_timer_cb));
    _orb_timer.startPeriodic(uavcan::MonotonicDuration::fromMSec(1000 / ESC_STATUS_UPDATE_RATE_HZ));

    return res;
}

void
UavcanEscController::update_outputs(bool stop_motors, uint16_t outputs[MAX_ACTUATORS], unsigned num_outputs)
{
    if (num_outputs > uavcan::equipment::esc::RawCommand::FieldTypes::cmd::MaxSize) {
        num_outputs = uavcan::equipment::esc::RawCommand::FieldTypes::cmd::MaxSize;
    }

    if (num_outputs > esc_status_s::CONNECTED_ESC_MAX) {
        num_outputs = esc_status_s::CONNECTED_ESC_MAX;
    }

    /*
     * Rate limiting - we don't want to congest the bus
     */
    const auto timestamp = _node.getMonotonicTime();

    if ((timestamp - _prev_cmd_pub).toUSec() < (1000000 / MAX_RATE_HZ)) {
        return;
    }

    _prev_cmd_pub = timestamp;

    /*
     * Fill the command message
     * If unarmed, we publish an empty message anyway
     */
    uavcan::equipment::esc::RawCommand msg;

    for (unsigned i = 0; i < num_outputs; i++) {
        if (stop_motors || outputs[i] == DISARMED_OUTPUT_VALUE) {
            msg.cmd.push_back(static_cast<unsigned>(0));

        } else {
            msg.cmd.push_back(static_cast<int>(outputs[i]));
        }
    }

    /*
     * Remove channels that are always zero.
     * The objective of this optimization is to avoid broadcasting multi-frame transfers when a single frame
     * transfer would be enough. This is a valid optimization as the UAVCAN specification implies that all
     * non-specified ESC setpoints should be considered zero.
     * The positive outcome is a (marginally) lower bus traffic and lower CPU load.
     *
     * From the standpoint of the PX4 architecture, however, this is a hack. It should be investigated why
     * the mixer returns more outputs than are actually used.
     */
    for (int index = int(msg.cmd.size()) - 1; index >= _max_number_of_nonzero_outputs; index--) {
        if (msg.cmd[index] != 0) {
            _max_number_of_nonzero_outputs = index + 1;
            break;
        }
    }

    msg.cmd.resize(_max_number_of_nonzero_outputs);

    /*
     * Publish the command message to the bus
     * Note that for a quadrotor it takes one CAN frame
     */
    _uavcan_pub_raw_cmd.broadcast(msg);
}

void
UavcanEscController::esc_status_sub_cb(const uavcan::ReceivedDataStructure<uavcan::equipment::esc::Status> &msg)
{
    if (msg.esc_index < esc_status_s::CONNECTED_ESC_MAX) {
        auto &ref = _esc_status.esc[msg.esc_index];

        ref.esc_address = msg.getSrcNodeID().get();
        ref.timestamp       = hrt_absolute_time();
        ref.esc_voltage     = msg.voltage;
        ref.esc_current     = msg.current;
        ref.esc_temperature = msg.temperature;
        ref.esc_rpm         = msg.rpm;
        ref.esc_errorcount  = msg.error_count;
    }
}

void
UavcanEscController::orb_pub_timer_cb(const uavcan::TimerEvent &)
{
    _esc_status.timestamp = hrt_absolute_time();
    _esc_status.esc_count = _rotor_count;
    _esc_status.counter += 1;
    _esc_status.esc_connectiontype = esc_status_s::ESC_CONNECTION_TYPE_CAN;
    _esc_status.esc_online_flags = check_escs_status();

    _esc_status_pub.publish(_esc_status);
}

uint8_t
UavcanEscController::check_escs_status()
{
    int esc_status_flags = 0;
    const hrt_abstime now = hrt_absolute_time();

    for (int index = 0; index < esc_status_s::CONNECTED_ESC_MAX; index++) {

        if (_esc_status.esc[index].timestamp > 0 && now - _esc_status.esc[index].timestamp < 1200_ms) {
            esc_status_flags |= (1 << index);
        }

    }

    return esc_status_flags;
}