libiio  0.23
Library for interfacing with IIO devices

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.

* libiio - AD9361 IIO streaming example
* Copyright (C) 2014 IABG mbH
* Author: Michael Feilen <>
* This program 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 2
* of the License, or (at your option) any later version.
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#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()
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); }
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
* 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");
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");
txbuf = iio_device_create_buffer(tx, 1024*1024, false);
if (!txbuf) {
perror("Could not create TX buffer");
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
((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);
return 0;
void * iio_buffer_end(const struct iio_buffer *buffer)
Get the address that follows the last sample in a buffer.
Definition: buffer.c:293
Represents an input or output channel of a device.
ssize_t iio_buffer_push(struct iio_buffer *buffer)
Send the samples to the hardware.
Definition: buffer.c:147
struct iio_channel * iio_device_find_channel(const struct iio_device *dev, const char *name, bool output)
Try to find a channel structure by its name of ID.
Definition: device.c:157
int iio_channel_attr_write_longlong(const struct iio_channel *chn, const char *attr, long long val)
Set the value of the given channel-specific attribute.
Definition: channel.c:644
ssize_t iio_channel_attr_write(const struct iio_channel *chn, const char *attr, const char *src)
Set the value of the given channel-specific attribute.
Definition: channel.c:334
void iio_channel_enable(struct iio_channel *chn)
Enable the given channel.
Definition: channel.c:367
void iio_channel_disable(struct iio_channel *chn)
Disable the given channel.
Definition: channel.c:373
ptrdiff_t iio_buffer_step(const struct iio_buffer *buffer)
Get the step size between two samples of one channel.
Definition: buffer.c:288
Public interface.
ssize_t iio_buffer_refill(struct iio_buffer *buffer)
Fetch more samples from the hardware.
Definition: buffer.c:123
unsigned int iio_context_get_devices_count(const struct iio_context *ctx)
Enumerate the devices found in the given context.
Definition: context.c:280
An input or output buffer, used to read or write samples.
void iio_context_destroy(struct iio_context *ctx)
Destroy the given context.
Definition: context.c:258
void iio_buffer_destroy(struct iio_buffer *buffer)
Destroy the given buffer.
Definition: buffer.c:104
ssize_t iio_device_get_sample_size(const struct iio_device *dev)
Get the current sample size.
Definition: device.c:476
Contains the representation of an IIO context.
void * iio_buffer_first(const struct iio_buffer *buffer, const struct iio_channel *chn)
Find the first sample of a channel in a buffer.
Definition: buffer.c:250
Represents a device in the IIO context.
struct iio_context * iio_create_context_from_uri(const char *uri)
Create a context from a URI description.
Definition: context.c:394
struct iio_device * iio_context_find_device(const struct iio_context *ctx, const char *name)
Try to find a device structure by its ID, label or name.
Definition: context.c:294
struct iio_buffer * iio_device_create_buffer(const struct iio_device *dev, size_t samples_count, bool cyclic)
Create an input or output buffer associated to the given device.
Definition: buffer.c:26
struct iio_context * iio_create_default_context(void)
Create a context from local or remote IIO devices.
Definition: context.c:415