bindings/csharp: pluto example

- How to use C# bindings to control libiio devices.
- Configure Pluto and use RX and TX interfaces to send and receive data.
- Nice to have for EZ questions such as:  https://ez.analog.com/adieducation/university-program/f/q-a/574101/adalam-pluto-sdr-via-c

Signed-off-by: Adrian Stanea <[email protected]>

bindings/csharp/examples/PlutoExample.cs

@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * libiio - Library for interfacing industrial I/O (IIO) devices
+ *
+ * Copyright (C) 2023 Analog Devices, Inc.
+ * Author: Adrian Stanea <[email protected]>
+ */
+
+using System;
+using System.Reflection;
+using iio;
+
+[assembly: AssemblyTitle("Pluto_Example")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: System.Runtime.InteropServices.ComVisible(false)]
+[assembly: CLSCompliant(true)]
+namespace IIOCSharp
+{
+    static class PlutoExample
+    {
+        const int INT16_BYTE_STEP = 2;
+        const string URI = "ip:pluto.local";
+        const double TXLO = 1_000_000_000;
+        const double TXBW = 5_000_000;
+        const double TXFS = 3_000_000;
+        const double RXLO = TXLO;
+        const double RXBW = TXBW;
+        const double RXFS = TXFS;
+        const string GAIN_CTRL_MODE = "slow_attack";
+        const double HW_GAIN = -30;
+
+        const string CHN_VOLTAGE0 = "voltage0";
+        const string CHN_VOLTAGE1 = "voltage1";
+
+        static void Main(string[] args)
+        {
+            Context ctx = new Context(URI);
+            if (ctx == null)
+            {
+                Console.WriteLine("Unable to create IIO context");
+                return;
+            }
+            // get reference to devices
+            var ctrl = ctx.find_device("ad9361-phy");
+            var tx_dac = ctx.find_device("cf-ad9361-dds-core-lpc");
+            var rx_adc = ctx.find_device("cf-ad9361-lpc");
+
+            rx_config(ctrl, RXLO, RXBW, RXFS, GAIN_CTRL_MODE);
+            tx_config(ctrl, TXLO, TXBW, TXFS, HW_GAIN);
+
+            // Enable all IQ channels
+            enable_tx(tx_dac);
+            enable_rx(rx_adc);
+
+            // Cyclic buffer to output perdiodic waveforms
+            uint samples_per_channel = Convert.ToUInt16(Math.Pow(2, 15));
+
+            var tx_buf = new IOBuffer(tx_dac, samples_per_channel, true);
+            var rx_buff = new IOBuffer(rx_adc, samples_per_channel, false);
+
+            byte[] iqBytes = generate_sine(Convert.ToInt32(samples_per_channel), RXFS);
+
+            // Send data to TX buffer
+            tx_buf.fill(iqBytes);
+            tx_buf.push();
+
+            // read data on rx buffer
+            const int num_readings = 10;
+            (List<int> reals, List<int> imags) = read_rx_data(rx_buff, num_readings, Convert.ToInt32(samples_per_channel));
+        }
+
+        static void rx_config(Device device, double rx_lo, double rx_bw, double rx_fs, string gain_ctrl_mode)
+        {
+            var rx_chn = device.find_channel(CHN_VOLTAGE0, false);
+
+            device.find_channel("RX_LO", true).find_attribute("frequency").write(rx_lo);
+            rx_chn.find_attribute("rf_bandwidth").write(rx_bw);
+            rx_chn.find_attribute("sampling_frequency").write(rx_fs);
+            rx_chn.find_attribute("gain_control_mode").write(gain_ctrl_mode);
+        }
+
+        static void tx_config(Device device, double tx_lo, double tx_bw, double tx_fs, double hw_gain)
+        {
+            var tx_chn = device.find_channel(CHN_VOLTAGE0, true);
+
+            device.find_channel("TX_LO", true).find_attribute("frequency").write(tx_lo);
+            tx_chn.find_attribute("rf_bandwidth").write(tx_bw);
+            tx_chn.find_attribute("sampling_frequency").write(tx_fs);
+            tx_chn.find_attribute("hardwaregain").write(hw_gain);
+        }
+
+        static void enable_tx(Device tx_adc)
+        {
+            tx_adc.find_channel(CHN_VOLTAGE0, true).enable();
+            tx_adc.find_channel(CHN_VOLTAGE1, true).enable();
+        }
+
+        static void enable_rx(Device rx_dac)
+        {
+            rx_dac.find_channel(CHN_VOLTAGE0, false).enable();
+            rx_dac.find_channel(CHN_VOLTAGE1, false).enable();
+        }
+
+        static byte[] generate_sine(int samples_per_channel, double rx_fs)
+        {
+            const int fc = 10000;
+            double ts = 1.0 / rx_fs;
+            double[] t = Enumerable.Range(0, samples_per_channel).Select(i => i * ts).ToArray();
+
+            double[] i = t.Select(x => (Math.Sin(2 * Math.PI * x * fc) * Math.Pow(2, 14))).ToArray();
+            double[] q = t.Select(x => (Math.Cos(2 * Math.PI * x * fc) * Math.Pow(2, 14))).ToArray();
+
+            Int16[] iq = new Int16[i.Length + q.Length];
+            for (int j = 0; j < i.Length; j++)
+            {
+                iq[j * INT16_BYTE_STEP] = Convert.ToInt16(i[j]);
+                iq[j * INT16_BYTE_STEP + 1] = Convert.ToInt16(q[j]);
+            }
+
+            byte[] iqBytes = iq.SelectMany(BitConverter.GetBytes).ToArray();
+            return iqBytes;
+        }
+
+        static (List<int> reals, List<int> imags) read_rx_data(IOBuffer rx_buff, int num_readings, int samples_per_channel)
+        {
+            List<int> reals = new List<int>();
+            List<int> imags = new List<int>();
+
+            byte[] data = new byte[samples_per_channel];
+            for (int k = 0; k < num_readings; k++)
+            {
+                rx_buff.refill();
+                rx_buff.read(data);
+
+                Int16[] data_casted = new Int16[data.Length / INT16_BYTE_STEP];
+                Buffer.BlockCopy(data, 0, data_casted, 0, data.Length);
+                for (int idx = 0; idx < data_casted.Length; idx += INT16_BYTE_STEP)
+                {
+                    reals.Add(data_casted[idx]);
+                    imags.Add(data_casted[idx + 1]);
+                }
+            }
+            return (reals, imags);
+        }
+    }
+}