uhd/host/examples/rx_multi_samples.cpp

//
// Copyright 2011 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//

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

namespace po = boost::program_options;

int UHD_SAFE_MAIN(int argc, char *argv[]){
    uhd::set_thread_priority_safe();

    //variables to be set by po
    std::string args, sync, subdev, channel_list;
    double seconds_in_future;
    size_t total_num_samps;
    double rate;

    //setup the program options
    po::options_description desc("Allowed options");
    desc.add_options()
        ("help", "help message")
        ("args", po::value<std::string>(&args)->default_value(""), "single uhd device address args")
        ("secs", po::value<double>(&seconds_in_future)->default_value(1.5), "number of seconds in the future to receive")
        ("nsamps", po::value<size_t>(&total_num_samps)->default_value(10000), "total number of samples to receive")
        ("rate", po::value<double>(&rate)->default_value(100e6/16), "rate of incoming samples")
        ("sync", po::value<std::string>(&sync)->default_value("now"), "synchronization method: now, pps, mimo")
        ("subdev", po::value<std::string>(&subdev), "subdev spec (homogeneous across motherboards)")
        ("dilv", "specify to disable inner-loop verbose")
        ("channels", po::value<std::string>(&channel_list)->default_value("0"), "which channel(s) to use (specify \"0\", \"1\", \"0,1\", etc)")
    ;
    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 RX Multi Samples %s") % desc << std::endl;
        std::cout <<
        "    This is a demonstration of how to receive aligned data from multiple channels.\n"
        "    This example can receive from multiple DSPs, multiple motherboards, or both.\n"
        "    The MIMO cable or PPS can be used to synchronize the configuration. See --sync\n"
        "\n"
        "    Specify --subdev to select multiple channels per motherboard.\n"
        "      Ex: --subdev=\"0:A 0:B\" to get 2 channels on a Basic RX.\n"
        "\n"
        "    Specify --args to select multiple motherboards in a configuration.\n"
        "      Ex: --args=\"addr0=192.168.10.2, addr1=192.168.10.3\"\n"
        << std::endl;
        return ~0;
    }

    bool verbose = vm.count("dilv") == 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);

    //always select the subdevice first, the channel mapping affects the other settings
    if (vm.count("subdev")) usrp->set_rx_subdev_spec(subdev); //sets across all mboards

    std::cout << boost::format("Using Device: %s") % usrp->get_pp_string() << std::endl;

    //set the rx sample rate (sets across all channels)
    std::cout << boost::format("Setting RX Rate: %f Msps...") % (rate/1e6) << std::endl;
    usrp->set_rx_rate(rate);
    std::cout << boost::format("Actual RX Rate: %f Msps...") % (usrp->get_rx_rate()/1e6) << std::endl << std::endl;

    std::cout << boost::format("Setting device timestamp to 0...") << std::endl;
    if (sync == "now"){
        //This is not a true time lock, the devices will be off by a few RTT.
        //Rather, this is just to allow for demonstration of the code below.
        usrp->set_time_now(uhd::time_spec_t(0.0));
    }
    else if (sync == "pps"){
        usrp->set_time_source("external");
        usrp->set_time_unknown_pps(uhd::time_spec_t(0.0));
        boost::this_thread::sleep(boost::posix_time::seconds(1)); //wait for pps sync pulse
    }
    else if (sync == "mimo"){
        UHD_ASSERT_THROW(usrp->get_num_mboards() == 2);

        //make mboard 1 a slave over the MIMO Cable
        usrp->set_clock_source("mimo", 1);
        usrp->set_time_source("mimo", 1);

        //set time on the master (mboard 0)
        usrp->set_time_now(uhd::time_spec_t(0.0), 0);

        //sleep a bit while the slave locks its time to the master
        boost::this_thread::sleep(boost::posix_time::milliseconds(100));
    }

    //detect which channels to use
    std::vector<std::string> channel_strings;
    std::vector<size_t> channel_nums;
    boost::split(channel_strings, channel_list, boost::is_any_of("\"',"));
    for(size_t ch = 0; ch < channel_strings.size(); ch++){
        size_t chan = std::stoi(channel_strings[ch]);
        if(chan >= usrp->get_rx_num_channels()){
            throw std::runtime_error("Invalid channel(s) specified.");
        }
        else channel_nums.push_back(std::stoi(channel_strings[ch]));
    }

    //create a receive streamer
    //linearly map channels (index0 = channel0, index1 = channel1, ...)
    uhd::stream_args_t stream_args("fc32"); //complex floats
    stream_args.channels = channel_nums;
    uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);

    //setup streaming
    std::cout << std::endl;
    std::cout << boost::format(
        "Begin streaming %u samples, %f seconds in the future..."
    ) % total_num_samps % seconds_in_future << std::endl;
    uhd::stream_cmd_t stream_cmd(uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE);
    stream_cmd.num_samps = total_num_samps;
    stream_cmd.stream_now = false;
    stream_cmd.time_spec = uhd::time_spec_t(seconds_in_future);
    rx_stream->issue_stream_cmd(stream_cmd); //tells all channels to stream

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

    //allocate buffers to receive with samples (one buffer per channel)
    const size_t samps_per_buff = rx_stream->get_max_num_samps();
    std::vector<std::vector<std::complex<float> > > buffs(
        usrp->get_rx_num_channels(), std::vector<std::complex<float> >(samps_per_buff)
    );

    //create a vector of pointers to point to each of the channel buffers
    std::vector<std::complex<float> *> buff_ptrs;
    for (size_t i = 0; i < buffs.size(); i++) buff_ptrs.push_back(&buffs[i].front());

    //the first call to recv() will block this many seconds before receiving
    double timeout = seconds_in_future + 0.1; //timeout (delay before receive + padding)

    size_t num_acc_samps = 0; //number of accumulated samples
    while(num_acc_samps < total_num_samps){
        //receive a single packet
        size_t num_rx_samps = rx_stream->recv(
            buff_ptrs, samps_per_buff, md, timeout
        );

        //use a small timeout for subsequent packets
        timeout = 0.1;

        //handle the error code
        if (md.error_code == uhd::rx_metadata_t::ERROR_CODE_TIMEOUT) break;
        if (md.error_code != uhd::rx_metadata_t::ERROR_CODE_NONE){
            throw std::runtime_error(str(boost::format(
                "Receiver error %s"
            ) % md.strerror()));
        }

        if(verbose) 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;

        num_acc_samps += num_rx_samps;
    }

    if (num_acc_samps < total_num_samps) std::cerr << "Receive timeout before all samples received..." << std::endl;

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

    return EXIT_SUCCESS;
}