C++ Interfacing Questions
- 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 -lusrpwhere 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:
./testusrp
- 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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * 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) */ int 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 buf[SAMPELS_PER_READ]; 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 *urx = usrp_standard_rx::make (which_board, decim, 1, -1, mode, fusb_block_size, fusb_nblocks); if (urx == 0) { 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 urx->set_nchannels(1); // Set ADC PGA gain urx->set_pga(0,gain); // Set FPGA Mux urx->set_mux(0x32103210); // Board A only // Set DDC decimation rate urx->set_decim_rate(decim); // Set DDC phase urx->set_ddc_phase(0,0); urx->start(); // Start data transfer printf("USRP Transfer Started\n"); // Do USRP Samples Reading for (i = 0; i < total_reads; i++) { urx->read(&buf, bufsize, &overrun); if (overrun) { printf ("USRP Rx Overrun\n"); noverruns++; } // Do whatever you want with the data process_data(&buf[0]); } 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.
