ad9361-iiostream.c

This example libiio program is meant to exercise the features of IIO functionality on the AD9361 found on the AD-FMCOMMS2-EBZ, AD-FMCOMMS3-EBZ, and the ADRV9361-Z7035 RF SOM.

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * libiio - AD9361 IIO streaming example
 *
 * Copyright (C) 2014 IABG mbH
 * Author: Michael Feilen <feilen_at_iabg.de>
 **/
 
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <signal.h>
#include <stdio.h>
#include <iio.h>
 
/* helper macros */
#define MHZ(x) ((long long)(x*1000000.0 + .5))
#define GHZ(x) ((long long)(x*1000000000.0 + .5))
 
#define IIO_ENSURE(expr) { \
    if (!(expr)) { \
        (void) fprintf(stderr, "assertion failed (%s:%d)\n", __FILE__, __LINE__); \
        (void) abort(); \
    } \
}
 
/* RX is input, TX is output */
enum iodev { RX, TX };
 
/* common RX and TX streaming params */
struct stream_cfg {
    long long bw_hz; // Analog banwidth in Hz
    long long fs_hz; // Baseband sample rate in Hz
    long long lo_hz; // Local oscillator frequency in Hz
    const char* rfport; // Port name
};
 
/* static scratch mem for strings */
static char tmpstr[64];
 
/* IIO structs required for streaming */
static struct iio_context *ctx   = NULL;
static struct iio_channel *rx0_i = NULL;
static struct iio_channel *rx0_q = NULL;
static struct iio_channel *tx0_i = NULL;
static struct iio_channel *tx0_q = NULL;
static struct iio_buffer  *rxbuf = NULL;
static struct iio_buffer  *txbuf = NULL;
 
static bool stop;
 
/* cleanup and exit */
static void shutdown(void)
{
    printf("* Destroying buffers\n");
    if (rxbuf) { iio_buffer_destroy(rxbuf); }
    if (txbuf) { iio_buffer_destroy(txbuf); }
 
    printf("* Disabling streaming channels\n");
    if (rx0_i) { iio_channel_disable(rx0_i); }
    if (rx0_q) { iio_channel_disable(rx0_q); }
    if (tx0_i) { iio_channel_disable(tx0_i); }
    if (tx0_q) { iio_channel_disable(tx0_q); }
 
    printf("* Destroying context\n");
    if (ctx) { iio_context_destroy(ctx); }
    exit(0);
}
 
static void handle_sig(int sig)
{
    printf("Waiting for process to finish... Got signal %d\n", sig);
    stop = true;
}
 
/* check return value of attr_write function */
static void errchk(int v, const char* what) {
     if (v < 0) { fprintf(stderr, "Error %d writing to channel \"%s\"\nvalue may not be supported.\n", v, what); shutdown(); }
}
 
/* write attribute: long long int */
static void wr_ch_lli(struct iio_channel *chn, const char* what, long long val)
{
    errchk(iio_channel_attr_write_longlong(chn, what, val), what);
}
 
/* write attribute: string */
static void wr_ch_str(struct iio_channel *chn, const char* what, const char* str)
{
    errchk(iio_channel_attr_write(chn, what, str), what);
}
 
/* helper function generating channel names */
static char* get_ch_name(const char* type, int id)
{
    snprintf(tmpstr, sizeof(tmpstr), "%s%d", type, id);
    return tmpstr;
}
 
/* returns ad9361 phy device */
static struct iio_device* get_ad9361_phy(void)
{
    struct iio_device *dev =  iio_context_find_device(ctx, "ad9361-phy");
    IIO_ENSURE(dev && "No ad9361-phy found");
    return dev;
}
 
/* finds AD9361 streaming IIO devices */
static bool get_ad9361_stream_dev(enum iodev d, struct iio_device **dev)
{
    switch (d) {
    case TX: *dev = iio_context_find_device(ctx, "cf-ad9361-dds-core-lpc"); return *dev != NULL;
    case RX: *dev = iio_context_find_device(ctx, "cf-ad9361-lpc");  return *dev != NULL;
    default: IIO_ENSURE(0); return false;
    }
}
 
/* finds AD9361 streaming IIO channels */
static bool get_ad9361_stream_ch(enum iodev d, struct iio_device *dev, int chid, struct iio_channel **chn)
{
    *chn = iio_device_find_channel(dev, get_ch_name("voltage", chid), d == TX);
    if (!*chn)
        *chn = iio_device_find_channel(dev, get_ch_name("altvoltage", chid), d == TX);
    return *chn != NULL;
}
 
/* finds AD9361 phy IIO configuration channel with id chid */
static bool get_phy_chan(enum iodev d, int chid, struct iio_channel **chn)
{
    switch (d) {
    case RX: *chn = iio_device_find_channel(get_ad9361_phy(), get_ch_name("voltage", chid), false); return *chn != NULL;
    case TX: *chn = iio_device_find_channel(get_ad9361_phy(), get_ch_name("voltage", chid), true);  return *chn != NULL;
    default: IIO_ENSURE(0); return false;
    }
}
 
/* finds AD9361 local oscillator IIO configuration channels */
static bool get_lo_chan(enum iodev d, struct iio_channel **chn)
{
    switch (d) {
     // LO chan is always output, i.e. true
    case RX: *chn = iio_device_find_channel(get_ad9361_phy(), get_ch_name("altvoltage", 0), true); return *chn != NULL;
    case TX: *chn = iio_device_find_channel(get_ad9361_phy(), get_ch_name("altvoltage", 1), true); return *chn != NULL;
    default: IIO_ENSURE(0); return false;
    }
}
 
/* applies streaming configuration through IIO */
bool cfg_ad9361_streaming_ch(struct stream_cfg *cfg, enum iodev type, int chid)
{
    struct iio_channel *chn = NULL;
 
    // Configure phy and lo channels
    printf("* Acquiring AD9361 phy channel %d\n", chid);
    if (!get_phy_chan(type, chid, &chn)) {  return false; }
    wr_ch_str(chn, "rf_port_select",     cfg->rfport);
    wr_ch_lli(chn, "rf_bandwidth",       cfg->bw_hz);
    wr_ch_lli(chn, "sampling_frequency", cfg->fs_hz);
 
    // Configure LO channel
    printf("* Acquiring AD9361 %s lo channel\n", type == TX ? "TX" : "RX");
    if (!get_lo_chan(type, &chn)) { return false; }
    wr_ch_lli(chn, "frequency", cfg->lo_hz);
    return true;
}
 
/* simple configuration and streaming */
/* usage:
 * Default context, assuming local IIO devices, i.e., this script is run on ADALM-Pluto for example
 $./a.out
 * URI context, find out the uri by typing `iio_info -s` at the command line of the host PC
 $./a.out usb:x.x.x
 */
int main (int argc, char **argv)
{
    // Streaming devices
    struct iio_device *tx;
    struct iio_device *rx;
 
    // RX and TX sample counters
    size_t nrx = 0;
    size_t ntx = 0;
 
    // Stream configurations
    struct stream_cfg rxcfg;
    struct stream_cfg txcfg;
 
    // Listen to ctrl+c and IIO_ENSURE
    signal(SIGINT, handle_sig);
 
    // RX stream config
    rxcfg.bw_hz = MHZ(2);   // 2 MHz rf bandwidth
    rxcfg.fs_hz = MHZ(2.5);   // 2.5 MS/s rx sample rate
    rxcfg.lo_hz = GHZ(2.5); // 2.5 GHz rf frequency
    rxcfg.rfport = "A_BALANCED"; // port A (select for rf freq.)
 
    // TX stream config
    txcfg.bw_hz = MHZ(1.5); // 1.5 MHz rf bandwidth
    txcfg.fs_hz = MHZ(2.5);   // 2.5 MS/s tx sample rate
    txcfg.lo_hz = GHZ(2.5); // 2.5 GHz rf frequency
    txcfg.rfport = "A"; // port A (select for rf freq.)
 
    printf("* Acquiring IIO context\n");
    if (argc == 1) {
        IIO_ENSURE((ctx = iio_create_default_context()) && "No context");
    }
    else if (argc == 2) {
        IIO_ENSURE((ctx = iio_create_context_from_uri(argv[1])) && "No context");
    }
    IIO_ENSURE(iio_context_get_devices_count(ctx) > 0 && "No devices");
 
    printf("* Acquiring AD9361 streaming devices\n");
    IIO_ENSURE(get_ad9361_stream_dev(TX, &tx) && "No tx dev found");
    IIO_ENSURE(get_ad9361_stream_dev(RX, &rx) && "No rx dev found");
 
    printf("* Configuring AD9361 for streaming\n");
    IIO_ENSURE(cfg_ad9361_streaming_ch(&rxcfg, RX, 0) && "RX port 0 not found");
    IIO_ENSURE(cfg_ad9361_streaming_ch(&txcfg, TX, 0) && "TX port 0 not found");
 
    printf("* Initializing AD9361 IIO streaming channels\n");
    IIO_ENSURE(get_ad9361_stream_ch(RX, rx, 0, &rx0_i) && "RX chan i not found");
    IIO_ENSURE(get_ad9361_stream_ch(RX, rx, 1, &rx0_q) && "RX chan q not found");
    IIO_ENSURE(get_ad9361_stream_ch(TX, tx, 0, &tx0_i) && "TX chan i not found");
    IIO_ENSURE(get_ad9361_stream_ch(TX, tx, 1, &tx0_q) && "TX chan q not found");
 
    printf("* Enabling IIO streaming channels\n");
    iio_channel_enable(rx0_i);
    iio_channel_enable(rx0_q);
    iio_channel_enable(tx0_i);
    iio_channel_enable(tx0_q);
 
    printf("* Creating non-cyclic IIO buffers with 1 MiS\n");
    rxbuf = iio_device_create_buffer(rx, 1024*1024, false);
    if (!rxbuf) {
        perror("Could not create RX buffer");
        shutdown();
    }
    txbuf = iio_device_create_buffer(tx, 1024*1024, false);
    if (!txbuf) {
        perror("Could not create TX buffer");
        shutdown();
    }
 
    printf("* Starting IO streaming (press CTRL+C to cancel)\n");
    while (!stop)
    {
        ssize_t nbytes_rx, nbytes_tx;
        char *p_dat, *p_end;
        ptrdiff_t p_inc;
 
        // Schedule TX buffer
        nbytes_tx = iio_buffer_push(txbuf);
        if (nbytes_tx < 0) { printf("Error pushing buf %d\n", (int) nbytes_tx); shutdown(); }
 
        // Refill RX buffer
        nbytes_rx = iio_buffer_refill(rxbuf);
        if (nbytes_rx < 0) { printf("Error refilling buf %d\n",(int) nbytes_rx); shutdown(); }
 
        // READ: Get pointers to RX buf and read IQ from RX buf port 0
        p_inc = iio_buffer_step(rxbuf);
        p_end = iio_buffer_end(rxbuf);
        for (p_dat = (char *)iio_buffer_first(rxbuf, rx0_i); p_dat < p_end; p_dat += p_inc) {
            // Example: swap I and Q
            const int16_t i = ((int16_t*)p_dat)[0]; // Real (I)
            const int16_t q = ((int16_t*)p_dat)[1]; // Imag (Q)
            ((int16_t*)p_dat)[0] = q;
            ((int16_t*)p_dat)[1] = i;
        }
 
        // WRITE: Get pointers to TX buf and write IQ to TX buf port 0
        p_inc = iio_buffer_step(txbuf);
        p_end = iio_buffer_end(txbuf);
        for (p_dat = (char *)iio_buffer_first(txbuf, tx0_i); p_dat < p_end; p_dat += p_inc) {
            // Example: fill with zeros
            // 12-bit sample needs to be MSB aligned so shift by 4
            // https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms2-ebz/software/basic_iq_datafiles#binary_format
            ((int16_t*)p_dat)[0] = 0 << 4; // Real (I)
            ((int16_t*)p_dat)[1] = 0 << 4; // Imag (Q)
        }
 
        // Sample counter increment and status output
        nrx += nbytes_rx / iio_device_get_sample_size(rx);
        ntx += nbytes_tx / iio_device_get_sample_size(tx);
        printf("\tRX %8.2f MSmp, TX %8.2f MSmp\n", nrx/1e6, ntx/1e6);
    }
 
    shutdown();
 
    return 0;
}