uhd/host/examples/test_timed_commands.cpp

//
// Copyright 2012 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//

#include <uhd/usrp/multi_usrp.hpp>
#include <uhd/utils/safe_main.hpp>
#include <uhd/utils/thread.hpp>
#include <boost/format.hpp>
#include <boost/program_options.hpp>
#include <complex>
#include <iostream>

namespace po = boost::program_options;

int UHD_SAFE_MAIN(int argc, char* argv[])
{
    // variables to be set by po
    std::string args;

    // setup the program options
    po::options_description desc("Allowed options");
    // clang-format off
    desc.add_options()
        ("help", "help message")
        ("args", po::value<std::string>(&args)->default_value(""), "single uhd device address args")
    ;
    // clang-format on
    po::variables_map vm;
    po::store(po::parse_command_line(argc, argv, desc), vm);
    po::notify(vm);

    // print the help message
    if (vm.count("help")) {
        std::cout << boost::format("UHD Test Timed Commands %s") % desc << std::endl;
        return ~0;
    }

    // create a usrp device
    std::cout << std::endl;
    std::cout << boost::format("Creating the usrp device with: %s...") % args
              << std::endl;
    uhd::usrp::multi_usrp::sptr usrp = uhd::usrp::multi_usrp::make(args);
    std::cout << boost::format("Using Device: %s") % usrp->get_pp_string() << std::endl;

    // check if timed commands are supported
    std::cout << std::endl;
    std::cout << "Testing support for timed commands on this hardware... " << std::flush;
    try {
        usrp->set_command_time(uhd::time_spec_t(0.0));
        usrp->clear_command_time();
    } catch (const std::exception& e) {
        std::cout << "fail" << std::endl;
        std::cerr << "Got exception: " << e.what() << std::endl;
        std::cerr << "Timed commands are not supported on this hardware." << std::endl;
        return ~0;
    }
    std::cout << "pass" << std::endl;

    // readback time really fast, time diff is small
    std::cout << std::endl;
    std::cout << "Perform fast readback of registers:" << std::endl;
    uhd::time_spec_t total_time;
    for (size_t i = 0; i < 100; i++) {
        const uhd::time_spec_t t0 = usrp->get_time_now();
        const uhd::time_spec_t t1 = usrp->get_time_now();
        total_time += (t1 - t0);
    }
    std::cout << boost::format(" Difference between paired reads: %f us")
                     % (total_time.get_real_secs() / 100 * 1e6)
              << std::endl;

    // test timed control command
    // issues get_time_now() command twice a fixed time apart
    // outputs difference for each response time vs. the expected time
    // and difference between actual and expected time deltas
    std::cout << std::endl;
    std::cout << "Testing control timed command:" << std::endl;
    const uhd::time_spec_t span      = uhd::time_spec_t(0.1);
    const uhd::time_spec_t now       = usrp->get_time_now();
    const uhd::time_spec_t cmd_time1 = now + uhd::time_spec_t(0.1);
    const uhd::time_spec_t cmd_time2 = cmd_time1 + span;
    usrp->set_command_time(cmd_time1);
    uhd::time_spec_t response_time1 = usrp->get_time_now();
    usrp->set_command_time(cmd_time2);
    uhd::time_spec_t response_time2 = usrp->get_time_now();
    usrp->clear_command_time();
    std::cout << boost::format(" Span      : %f us\n"
                               " Now       : %f us\n"
                               " Response 1: %f us\n"
                               " Response 2: %f us")
                     % (span.get_real_secs() * 1e6) % (now.get_real_secs() * 1e6)
                     % (response_time1.get_real_secs() * 1e6)
                     % (response_time2.get_real_secs() * 1e6)
              << std::endl;
    std::cout << boost::format(" Difference of response time 1: %f us")
                     % ((response_time1 - cmd_time1).get_real_secs() * 1e6)
              << std::endl;
    std::cout << boost::format(" Difference of response time 2: %f us")
                     % ((response_time2 - cmd_time2).get_real_secs() * 1e6)
              << std::endl;
    std::cout << boost::format(
                     " Difference between actual and expected time delta: %f us")
                     % ((response_time2 - response_time1 - span).get_real_secs() * 1e6)
              << std::endl;

    // use a timed command to start a stream at a specific time
    // this is not the right way start streaming at time x,
    // but it should approximate it within control RTT/2
    // setup streaming
    std::cout << std::endl;
    std::cout << "About to start streaming using timed command:" << std::endl;

    // create a receive streamer
    uhd::stream_args_t stream_args("fc32"); // complex floats
    uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);

    uhd::stream_cmd_t stream_cmd(uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE);
    stream_cmd.num_samps               = 100;
    stream_cmd.stream_now              = false;
    const uhd::time_spec_t stream_time = usrp->get_time_now() + uhd::time_spec_t(0.1);
    stream_cmd.time_spec               = stream_time;
    rx_stream->issue_stream_cmd(stream_cmd);

    // meta-data will be filled in by recv()
    uhd::rx_metadata_t md;

    // allocate buffer to receive with samples
    std::vector<std::complex<float>> buff(stream_cmd.num_samps);

    const size_t num_rx_samps = rx_stream->recv(&buff.front(), buff.size(), md, 1.0);
    if (md.error_code != uhd::rx_metadata_t::ERROR_CODE_NONE) {
        throw std::runtime_error(str(boost::format("Receiver error %s") % md.strerror()));
    }
    std::cout << boost::format(" Received packet: %u samples, %u full secs, %f frac secs")
                     % num_rx_samps % md.time_spec.get_full_secs()
                     % md.time_spec.get_frac_secs()
              << std::endl;
    std::cout << boost::format(" Stream time was: %u full secs, %f frac secs")
                     % stream_time.get_full_secs() % stream_time.get_frac_secs()
              << std::endl;
    std::cout << boost::format(" Difference between stream time and first packet: %f us")
                     % ((md.time_spec - stream_time).get_real_secs() * 1e6)
              << std::endl;

    // finished
    std::cout << std::endl << "Done!" << std::endl << std::endl;

    return EXIT_SUCCESS;
}