examples/ad9371-iiostream.c

/*
 * libiio - AD9371 IIO streaming example
 *
 * Copyright (C) 2014 IABG mbH
 * Author: Michael Feilen <feilen_at_iabg.de>
 * Copyright (C) 2017 Analog Devices Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 **/

#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <signal.h>
#include <stdio.h>

#ifdef __APPLE__
#include <iio/iio.h>
#else
#include <iio.h>
#endif

/* helper macros */
#define MHZ(x) ((long long)(x*1000000.0 + .5))
#define GHZ(x) ((long long)(x*1000000000.0 + .5))

#define ASSERT(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 lo_hz; // Local oscillator frequency in Hz
};

/* 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); }
	exit(0);
}

static void handle_sig(int sig)
{
	printf("Waiting for process to finish...\n");
	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: long long int */
static long long rd_ch_lli(struct iio_channel *chn, const char* what)
{
	long long val;

	errchk(iio_channel_attr_read_longlong(chn, what, &val), what);

	printf("\t %s: %lld\n", what, val);
	return val;
}

#if 0
/* 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);
}
#endif

/* helper function generating channel names */
static char* get_ch_name_mod(const char* type, int id, char modify)
{
	snprintf(tmpstr, sizeof(tmpstr), "%s%d_%c", type, id, modify);
	return tmpstr;
}

/* 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 ad9371 phy device */
static struct iio_device* get_ad9371_phy(struct iio_context *ctx)
{
	struct iio_device *dev =  iio_context_find_device(ctx, "ad9371-phy");
	ASSERT(dev && "No ad9371-phy found");
	return dev;
}

/* finds AD9371 streaming IIO devices */
static bool get_ad9371_stream_dev(struct iio_context *ctx, enum iodev d, struct iio_device **dev)
{
	switch (d) {
	case TX: *dev = iio_context_find_device(ctx, "axi-ad9371-tx-hpc"); return *dev != NULL;
	case RX: *dev = iio_context_find_device(ctx, "axi-ad9371-rx-hpc");  return *dev != NULL;
	default: ASSERT(0); return false;
	}
}

/* finds AD9371 streaming IIO channels */
static bool get_ad9371_stream_ch(struct iio_context *ctx, enum iodev d, struct iio_device *dev, int chid, char modify, struct iio_channel **chn)
{
	*chn = iio_device_find_channel(dev, modify ? get_ch_name_mod("voltage", chid, modify) : get_ch_name("voltage", chid), d == TX);
	if (!*chn)
		*chn = iio_device_find_channel(dev, modify ? get_ch_name_mod("voltage", chid, modify) : get_ch_name("voltage", chid), d == TX);
	return *chn != NULL;
}

/* finds AD9371 phy IIO configuration channel with id chid */
static bool get_phy_chan(struct iio_context *ctx, enum iodev d, int chid, struct iio_channel **chn)
{
	switch (d) {
	case RX: *chn = iio_device_find_channel(get_ad9371_phy(ctx), get_ch_name("voltage", chid), false); return *chn != NULL;
	case TX: *chn = iio_device_find_channel(get_ad9371_phy(ctx), get_ch_name("voltage", chid), true);  return *chn != NULL;
	default: ASSERT(0); return false;
	}
}

/* finds AD9371 local oscillator IIO configuration channels */
static bool get_lo_chan(struct iio_context *ctx, 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_ad9371_phy(ctx), get_ch_name("altvoltage", 0), true); return *chn != NULL;
	case TX: *chn = iio_device_find_channel(get_ad9371_phy(ctx), get_ch_name("altvoltage", 1), true); return *chn != NULL;
	default: ASSERT(0); return false;
	}
}

/* applies streaming configuration through IIO */
bool cfg_ad9371_streaming_ch(struct iio_context *ctx, struct stream_cfg *cfg, enum iodev type, int chid)
{
	struct iio_channel *chn = NULL;

	// Configure phy and lo channels
	printf("* Acquiring AD9371 phy %s channel %d\n", type == TX ? "TX" : "RX", chid);
	if (!get_phy_chan(ctx, type, chid, &chn)) {	return false; }

	rd_ch_lli(chn, "rf_bandwidth");
	rd_ch_lli(chn, "sampling_frequency");

	// Configure LO channel
	printf("* Acquiring AD9371 %s lo channel\n", type == TX ? "TX" : "RX");
	if (!get_lo_chan(ctx, type, &chn)) { return false; }
	wr_ch_lli(chn, type == TX ? "TX_LO_frequency" : "RX_LO_frequency" , cfg->lo_hz);
	return true;
}

/* simple configuration and streaming */
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 ASSERT
	signal(SIGINT, handle_sig);

	// RX stream config
	rxcfg.lo_hz = GHZ(2.5); // 2.5 GHz rf frequency

	// TX stream config
	txcfg.lo_hz = GHZ(2.5); // 2.5 GHz rf frequency

	printf("* Acquiring IIO context\n");
	ASSERT((ctx = iio_create_default_context()) && "No context");
	ASSERT(iio_context_get_devices_count(ctx) > 0 && "No devices");

	printf("* Acquiring AD9371 streaming devices\n");
	ASSERT(get_ad9371_stream_dev(ctx, TX, &tx) && "No tx dev found");
	ASSERT(get_ad9371_stream_dev(ctx, RX, &rx) && "No rx dev found");

	printf("* Configuring AD9371 for streaming\n");
	ASSERT(cfg_ad9371_streaming_ch(ctx, &rxcfg, RX, 0) && "RX port 0 not found");
	ASSERT(cfg_ad9371_streaming_ch(ctx, &txcfg, TX, 0) && "TX port 0 not found");

	printf("* Initializing AD9371 IIO streaming channels\n");
	ASSERT(get_ad9371_stream_ch(ctx, RX, rx, 0, 'i', &rx0_i) && "RX chan i not found");
	ASSERT(get_ad9371_stream_ch(ctx, RX, rx, 0, 'q', &rx0_q) && "RX chan q not found");
	ASSERT(get_ad9371_stream_ch(ctx, TX, tx, 0, 0, &tx0_i) && "TX chan i not found");
	ASSERT(get_ad9371_stream_ch(ctx, TX, tx, 1, 0, &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 = 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 = iio_buffer_first(txbuf, tx0_i); p_dat < p_end; p_dat += p_inc) {
			// Example: fill with zeros
			// 14-bit sample needs to be MSB alligned so shift by 2
			// https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms2-ebz/software/basic_iq_datafiles#binary_format
			((int16_t*)p_dat)[0] = 0 << 2; // Real (I)
			((int16_t*)p_dat)[1] = 0 << 2; // 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;
}