Since I haven’t written any C++ since the primordial epoch of the late '90s, I had to use Microsoft’s new Coding Wizard, Github Copilot, to help me write something to fix the buffer overrun issue.
Now I get a WAV file, but it skips time. I think this is implemented kind of backwards. I would write an app and put the sampling in a background thread. I think I need to do it continuously.
Progress, though.
/**
@file singleRX.cpp
@author Lime Microsystems (www.limemicro.com)
@brief RX example
*/
// Try to get this to demodulate FM radio with the blog entry at:
// https://witestlab.poly.edu/blog/capture-and-decode-fm-radio/
// #define USE_GNU_PLOT
#include "lime/LimeSuite.h"
#include <iostream>
#include <chrono>
#include <fstream>
#ifdef USE_GNU_PLOT
#include "gnuPlotPipe.h"
#endif
#include <complex>
#include <thread>
#include <queue>
#include <mutex>
#include <condition_variable>
#include <boost/lockfree/queue.hpp>
using namespace std;
lms_device_t *device = NULL;
std::mutex mtx;
boost::lockfree::queue<float *> sampleQueue(128);
std::atomic<bool> dataAvailable(false);
std::atomic<bool> exitFlag(false);
std::condition_variable cv;
const int buffersize = 1000000; // complex samples per buffer
int error()
{
if (device != NULL)
LMS_Close(device);
exit(-1);
}
void writeSamplesToFile(const std::string &filename)
{
std::ofstream samplecsv(filename);
while (true)
{
float *buffer = nullptr;
while (!sampleQueue.pop(buffer))
{
// Wait for data to become available
std::unique_lock<std::mutex> lock(mtx);
cv.wait(lock, []
{ return dataAvailable.load() || exitFlag.load(); }); // Check the flag here
dataAvailable.store(false);
}
for (int i = 0; i < buffersize; i++)
{
samplecsv << buffer[i];
if (i % 2 == 0)
{
samplecsv << ",";
}
else
{
samplecsv << "\n";
}
}
if (exitFlag.load())
break;
// Don't forget to delete the buffer when you're done with it
delete[] buffer;
}
}
int main(int argc, char **argv)
{
// Find devices
// First we find number of devices, then allocate large enough list, and then populate the list
int n;
if ((n = LMS_GetDeviceList(NULL)) < 0) // Pass NULL to only obtain number of devices
error();
cout << "Devices found: " << n << endl;
if (n < 1)
return -1;
lms_info_str_t *list = new lms_info_str_t[n]; // allocate device list
if (LMS_GetDeviceList(list) < 0) // Populate device list
error();
for (int i = 0; i < n; i++) // print device list
cout << i << ": " << list[i] << endl;
cout << endl;
// Open the first device
if (LMS_Open(&device, list[0], NULL))
error();
delete[] list; // free device list
// Initialize device with default configuration
// Do not use if you want to keep existing configuration
// Use LMS_LoadConfig(device, "/path/to/file.ini") to load config from INI
if (LMS_Init(device) != 0)
error();
// Enable RX channel
// Channels are numbered starting at 0
if (LMS_EnableChannel(device, LMS_CH_RX, 0, true) != 0)
error();
if (LMS_EnableChannel(device, LMS_CH_TX, 0, true) != 0) // Fix for v2
error();
// Set center frequency to 800 MHz
int F_offset = 250000;
int desired_freq = 985 * 1e5 - F_offset;
if (LMS_SetLOFrequency(device, LMS_CH_RX, 0, desired_freq) != 0)
error();
// print currently set center frequency
float_type freq;
if (LMS_GetLOFrequency(device, LMS_CH_RX, 0, &freq) != 0)
error();
cout << "\nCenter frequency: " << freq / 1e6 << " MHz\n";
// select antenna port
lms_name_t antenna_list[10]; // large enough list for antenna names.
// Alternatively, NULL can be passed to LMS_GetAntennaList() to obtain number of antennae
if ((n = LMS_GetAntennaList(device, LMS_CH_RX, 0, antenna_list)) < 0)
error();
cout << "Available antennae:\n"; // print available antennae names
for (int i = 0; i < n; i++)
cout << i << ": " << antenna_list[i] << endl;
if ((n = LMS_GetAntenna(device, LMS_CH_RX, 0)) < 0) // get currently selected antenna index
error();
// print antenna index and name
cout << "Automatically selected antenna: " << n << ": " << antenna_list[n] << endl;
if (LMS_SetAntenna(device, LMS_CH_RX, 0, LMS_PATH_LNAW) != 0) // manually select antenna
error();
if ((n = LMS_GetAntenna(device, LMS_CH_RX, 0)) < 0) // get currently selected antenna index
error();
// print antenna index and name
cout << "Manually selected antenna: " << n << ": " << antenna_list[n] << endl;
// Set sample rate to 8 MHz, preferred oversampling in RF 8x
// This set sampling rate for all channels
if (LMS_SetSampleRate(device, 8e6, 8) != 0)
error();
// print resulting sampling rates (interface to host , and ADC)
float_type rate, rf_rate;
if (LMS_GetSampleRate(device, LMS_CH_RX, 0, &rate, &rf_rate) != 0) // NULL can be passed
error();
cout << "\nHost interface sample rate: " << rate / 1e6 << " MHz\nRF ADC sample rate: " << rf_rate / 1e6 << "MHz\n\n";
// Example of getting allowed parameter value range
// There are also functions to get other parameter ranges (check LimeSuite.h)
// Get allowed LPF bandwidth range
lms_range_t range;
if (LMS_GetLPFBWRange(device, LMS_CH_RX, &range) != 0)
error();
cout << "RX LPF bandwidth range: " << range.min / 1e6 << " - " << range.max / 1e6 << " MHz\n\n";
// Configure LPF, bandwidth 8 MHz
if (LMS_SetLPFBW(device, LMS_CH_RX, 0, 8e6) != 0)
error();
// Set RX gain
if (LMS_SetNormalizedGain(device, LMS_CH_RX, 0, 0.7) != 0)
error();
// Print RX gain
float_type gain; // normalized gain
if (LMS_GetNormalizedGain(device, LMS_CH_RX, 0, &gain) != 0)
error();
cout << "Normalized RX Gain: " << gain << endl;
unsigned int gaindB; // gain in dB
if (LMS_GetGaindB(device, LMS_CH_RX, 0, &gaindB) != 0)
error();
cout << "RX Gain: " << gaindB << " dB" << endl;
// Perform automatic calibration
if (LMS_Calibrate(device, LMS_CH_RX, 0, 8e6, 0) != 0)
error();
// Enable test signal generation
// To receive data from RF, remove this line or change signal to LMS_TESTSIG_NONE
// if (LMS_SetTestSignal(device, LMS_CH_RX, 0, LMS_TESTSIG_NCODIV8, 0, 0) != 0)
// error();
// Streaming Setup
// Initialize stream
lms_stream_t streamId;
streamId.channel = 0; // channel number
streamId.fifoSize = 1024 * 1024; // fifo size in samples
streamId.throughputVsLatency = 1.0; // optimize for max throughput
streamId.isTx = false; // RX channel
streamId.dataFmt = lms_stream_t::LMS_FMT_F32; // 32-bit floats
if (LMS_SetupStream(device, &streamId) != 0)
error();
LMS_StartStream(&streamId);
#ifdef USE_GNU_PLOT
GNUPlotPipe gp;
gp.write("set size square\n set xrange[-1:1]\n set yrange[-1:1]\n");
#endif
auto t1 = chrono::high_resolution_clock::now();
auto t2 = t1;
// In your main function or wherever you're receiving the samples:
string filename = "samples_" + to_string(freq / 1e6) + ".csv";
std::thread writerThread(writeSamplesToFile, filename);
while (chrono::high_resolution_clock::now() - t1 < chrono::seconds(10)) // run for 10 seconds
{
int samplesRead;
// Allocate a new buffer
float *buffer = new float[buffersize * 2];
lms_stream_status_t status;
if (LMS_GetStreamStatus(&streamId, &status) != 0)
{
// Handle error
cout << "Stream Status error" << endl;
}
// Receive samples
samplesRead = LMS_RecvStream(&streamId, buffer, buffersize, NULL, 1000);
if (samplesRead <= 0)
{
cout << "error: " << samplesRead << endl;
}
// cout << "Read " << samplesRead << " samples." << endl;
while (!sampleQueue.push(buffer))
;
dataAvailable.store(true);
cv.notify_one();
// I and Q samples are interleaved in buffer: IQIQIQ...
/*
INSERT CODE FOR PROCESSING RECEIVED SAMPLES
*/
// Print stats (once per second)
if (chrono::high_resolution_clock::now() - t2 > chrono::seconds(1))
{
t2 = chrono::high_resolution_clock::now();
lms_stream_status_t status;
// Get stream status
LMS_GetStreamStatus(&streamId, &status);
cout << "RX data rate: " << status.linkRate / 1e6 << " MB/s\n"; // link data rate
cout << "RX fifo: " << 100 * status.fifoFilledCount / status.fifoSize << "%" << endl; // percentage of FIFO filled
}
}
cout << "Finished sampling" << endl;
// Stop streaming
LMS_StopStream(&streamId); // stream is stopped but can be started again with LMS_StartStream()
LMS_DestroyStream(device, &streamId); // stream is deallocated and can no longer be used
// Close device
LMS_Close(device);
cout << "Waiting for samples to be written to file" << endl;
while (!sampleQueue.empty())
{
std::this_thread::sleep_for(std::chrono::milliseconds(100));
}
cout << "Complete" << endl;
// Don't forget to join the thread at the end of your program:
exitFlag.store(true);
cv.notify_one();
writerThread.join();
return 0;
}
