rpi_rc_in.cpp

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/****************************************************************************
 *
 *   Copyright (c) 2017 Fan.zhang. All rights reserved. 421395590@qq.com
 *   Copyright (c) 2017 PX4 Development Team. All rights reserved.
 *
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 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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#include "rpi_rc_in.h"

using namespace rpi_rc_in;

RcInput::~RcInput()
{
    if (_mem) {
        shmdt(_mem);
        _mem = nullptr;
    }

    ScheduleClear();
    _is_running = false;
}

int RcInput::rpi_rc_init()
{
    int i;

    // initialize shared memory
    if ((_shmid = shmget(_key, sizeof(int) * _channels, 0666)) < 0) {
        PX4_WARN("Faild to access shared memory");
        return -1;
    }

    if ((_mem = (int *) shmat(_shmid, NULL, 0)) == (void *) - 1) {
        PX4_WARN("Faild to map shared memory");
        return -1;
    }

    // publish data for all channels
    for (i = 0; i < input_rc_s::RC_INPUT_MAX_CHANNELS; ++i) {
        _data.values[i] = UINT16_MAX;
    }

    return 0;
}

int RcInput::start()
{
    int result = 0;

    result = rpi_rc_init();

    if (result != 0) {
        PX4_WARN("error: RC initialization failed");
        return -1;
    }

    _is_running = true;

    ScheduleNow();

    return result;
}

void RcInput::stop()
{
    _should_exit = true;
}

void RcInput::Run()
{
    _measure();

    if (!_should_exit) {
        ScheduleDelayed(RCINPUT_MEASURE_INTERVAL_US);
    }
}

void RcInput::_measure(void)
{
    uint64_t ts;
    // publish PWM data
    // read pwm value from shared memory
    int i = 0;

    for (i = 0; i < _channels; ++i) {
        int value = _mem[i]; // access the shared memory (with a single read)
        _data.values[i] = (value <= 0) ? UINT16_MAX : value;
    }

    ts = hrt_absolute_time();
    _data.timestamp = ts;
    _data.timestamp_last_signal = ts;
    _data.channel_count = _channels;
    _data.rssi = 100;
    _data.rc_lost_frame_count = 0;
    _data.rc_total_frame_count = 1;
    _data.rc_ppm_frame_length = 100;
    _data.rc_failsafe = false;
    _data.rc_lost = false;
    _data.input_source = input_rc_s::RC_INPUT_SOURCE_PX4IO_PPM;

    if (nullptr == _rcinput_pub) {
        int instance;
        _rcinput_pub = orb_advertise_multi(ORB_ID(input_rc), &_data, &instance, ORB_PRIO_DEFAULT);

    } else {
        orb_publish(ORB_ID(input_rc), _rcinput_pub, &_data);
    }
}

static void rpi_rc_in::usage(const char *reason)
{
    if (reason) {
        PX4_ERR("%s", reason);
    }

    PX4_INFO("rpi_rc_in {start|stop|status}");
}

int rpi_rc_in_main(int argc, char **argv)
{
    if (argc < 2) {
        usage("missing command");
        return 1;
    }

    if (!strcmp(argv[1], "start")) {

        if (rc_input != nullptr && rc_input->is_running()) {
            PX4_INFO("already running");
            // this is not an error
            return 0;
        }

        rc_input = new RcInput();

        // Check if alloc worked.
        if (nullptr == rc_input) {
            PX4_ERR("Rc input module initialization faild");
            return -1;
        }

        int ret = rc_input->start();

        if (ret != 0) {
            PX4_ERR("Rc input module failure");
        }

        return 0;
    }

    if (!strcmp(argv[1], "stop")) {

        if (rc_input == nullptr || !rc_input->is_running()) {
            PX4_WARN("Not running");
            // this is not an error
            return 0;
        }

        rc_input->stop();

        // Wait for task to die
        int i = 0;

        do {
            // wait for 100ms
            usleep(100000);

        } while (rc_input->is_running() && ++i < 30);

        delete rc_input;
        rc_input = nullptr;

        return 0;
    }

    if (!strcmp(argv[1], "status")) {
        if (rc_input != nullptr && rc_input->is_running()) {
            PX4_INFO("running");

        } else {
            PX4_INFO("Not running");
        }

        return 0;
    }

    usage("rpi_rc_in start|stop|status");
    return 1;

}