C++ 接口问题

  • How we can write Linux C++ application program to interface with USRP?

Here it how we can do it:

1) The gnuradio project provides a complete USRP interface library. When compiling the interface program, these library must be linked with our code by using G++ library command (-lusrp).

2) To show the used procedure, suppose we have written a C++ USRP interface program called usrp_test_c++.cpp. To compile this program, we use the following command:

$ g++ usrp_test_c++.cpp -o testusrp -lusrp

where g++ is the GNU C++ compiler, usrp_test_c++.cpp is our c++ source file, testusrp is our output file, -lusrp is the USRP C++ library.

Note: The following USRP two header files should be in the same compilation directory: fpga_regs_common.h, fpga_regs_standard.h

3) To run the output file from Linux command line:

  • Is there a simple C++ USRP interfacing demonstration program?

Below is the list for such program

// Simple C++ USRP interfacing demonstration program
// This program was derived and modified from test_usrp_standard_rx.cc

/* -*- c++ -*- */
* Copyright 2003,2006,2007,2008 Free Software Foundation, Inc.
* This file is part of GNU Radio
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.

#include "usrp_standard.h"

// Dummy Function to process USRP data
void process_data(int *buffer)
Each buffer element, for example buffer[0] contains 4 bytes
2 bytes For (I) and 2 bytes for (Q).

#define SAMPELS_PER_READ (512) // Must be a multiple of 128

SAMPELS_PER_READ :Each sample is consists of 4 bytes (2 bytes for I and
2 bytes for Q. Since the reading length from USRP should be multiple of 512
bytes see "usrp_basic.h", then we have to read multiple of 128 samples each
time (4 bytes * 128 sample = 512 bytes)

main (int argc, char **argv)
bool loopback_p = false;
bool counting_p = false;
bool width_8_p = false;
int which_board = 0;
int decim = 8; // 32 MB/sec
double center_freq = 0;
int fusb_block_size = 0;
int fusb_nblocks = 0;
int nchannels = 1;
int gain = 0;
int mode = 0;
int noverruns = 0;
bool overrun;
int total_reads = 10000;
int i;
int bufsize = SAMPELS_PER_READ*4; // Should be multiple of 512 Bytes

if (loopback_p) mode |= usrp_standard_rx::FPGA_MODE_LOOPBACK;

if (counting_p) mode |= usrp_standard_rx::FPGA_MODE_COUNTING;

usrp_standard_rx_sptr urx = usrp_standard_rx::make (which_board, decim, 1, -1, mode,
fusb_block_size, fusb_nblocks);

if (!urx)
fprintf (stderr, "Error: usrp_standard_rx::make\n");
exit (1);

if (width_8_p)
int width = 8;
int shift = 8;
bool want_q = true;
if (!urx->set_format(usrp_standard_rx::make_format(width, shift, want_q)))
fprintf (stderr, "Error: urx->set_format\n");
exit (1);

// Set DDC center frequency
urx->set_rx_freq (0, center_freq);

// Set Number of channels

// Set ADC PGA gain

// Set FPGA Mux
urx->set_mux(0x32103210); // Board A only

// Set DDC decimation rate

// Set DDC phase

urx->start(); // Start data transfer

printf("USRP Transfer Started\n");

// Do USRP Samples Reading
for (i = 0; i < total_reads; i++)
urx->read(&buf[0], bufsize, &overrun);

if (overrun)
printf ("USRP Rx Overrun\n");

// Do whatever you want with the data


urx->stop(); // Stop data transfer
printf("USRP Transfer Stoped\n");
delete urx;
return 0;

  • Currently, all USRP daughterboards control is handled from Python. Where I can find the C++ drivers for these boards?

The gnuradio team is developing an all C++ daughterboards drivers [I don’t know if they finished it]. There are some gnuradio users that developed their own C++ drivers but they did not publish it yet [I Think They Should].

The only published C++ driver is for DBSRX daughterboard by Gregory W Heckler.

  • Where can I obtain Gregory DBSRX driver ? How to use the driver ?

The DBSRX C++ driver can be obtained from GPS-SDR code repo.

We can use:

$ g++ db_dbs_rx.cpp usrp_sdr.cpp -o testdriver -lm -lusrp -lpthread

Note: The following files should be in the same compilation directory: db-dbs_rx.cpp, db_dbs_rx.h, fpga_regs_common.h, fpga_regs_standard.h.

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注:C++ Interfacing Questions(原文出处,翻译整理仅供参考!)