initial version with serial link

analog_system_monitor_dotnet/SerialManager.cs

@@ -0,0 +1,158 @@
+#nullable enable
+
+using System;
+using System.IO.Ports;
+using System.Linq;
+using System.Threading;
+
+public class SerialManager : IDisposable
+{
+    private SerialPort? port;
+    private DateTime lastResponse = DateTime.UtcNow;
+
+    private const int BaudRate = 115200;
+    private const int PingTimeoutMs = 300;
+    private const int WatchdogTimeoutMs = 3000;
+
+    public bool IsConnected => port != null && port.IsOpen;
+
+    // ---------------- DEVICE DISCOVERY ----------------
+
+    public void DiscoverDevice()
+    {
+        DisposePort();
+
+        foreach (string com in SerialPort.GetPortNames().OrderBy(s => s))
+        {
+            string? response = null;
+
+            try
+            {
+                using (var testPort = CreatePort(com, PingTimeoutMs))
+                {
+                    testPort.Open();
+                    Thread.Sleep(350); // RP2040 resets on open
+
+                    testPort.DiscardInBuffer();
+                    testPort.DiscardOutBuffer();
+
+                    testPort.Write("PING\n");
+
+                    try
+                    {
+                        if (testPort.BytesToRead > 0)
+                            response = testPort.ReadLine();
+                    }
+                    catch (TimeoutException)
+                    {
+                        // No response — move to next port
+                    }
+                }
+
+                if (response != null &&
+                    response.StartsWith("Analog_System_Monitor_"))
+                {
+                    port = CreatePort(com, 500);
+                    port.Open();
+                    Thread.Sleep(350); // allow RP2040 reboot again
+
+                    lastResponse = DateTime.UtcNow;
+                    return;
+                }
+            }
+            catch
+            {
+                // Silent fail — move to next COM port
+            }
+        }
+
+        port = null;
+    }
+
+    // ---------------- PORT FACTORY ----------------
+
+    private SerialPort CreatePort(string com, int timeout)
+    {
+        return new SerialPort(com, BaudRate)
+        {
+            Parity = Parity.None,
+            DataBits = 8,
+            StopBits = StopBits.One,
+            Handshake = Handshake.None,
+
+            NewLine = "\n",
+            Encoding = System.Text.Encoding.ASCII,
+
+            ReadTimeout = timeout,
+            WriteTimeout = timeout,
+
+            DtrEnable = true,   // REQUIRED for RP2040 USB CDC
+            RtsEnable = true
+        };
+    }
+
+    // ---------------- WATCHDOG ----------------
+
+    public bool WatchdogExpired =>
+        (DateTime.UtcNow - lastResponse).TotalMilliseconds > WatchdogTimeoutMs;
+
+    // ---------------- SEND COMMAND ----------------
+
+    public void SendSetAll(string cmd)
+    {
+        if (!IsConnected)
+            return;
+
+        try
+        {
+            port!.Write(cmd + "\n");
+
+            string? response = null;
+
+            try
+            {
+                if (port.BytesToRead > 0)
+                    response = port.ReadLine();
+            }
+            catch (TimeoutException)
+            {
+                // No response this tick — totally fine
+            }
+
+            if (response != null &&
+                (response.StartsWith("OK") || response.StartsWith("ERROR")))
+            {
+                lastResponse = DateTime.UtcNow;
+            }
+        }
+        catch
+        {
+            // Silent fail — watchdog will trigger reconnect
+        }
+    }
+
+    // ---------------- CLEANUP ----------------
+
+    private void DisposePort()
+    {
+        try
+        {
+            if (port != null)
+            {
+                port.Close();
+                port.Dispose();
+            }
+        }
+        catch
+        {
+            // ignore
+        }
+
+        port = null;
+    }
+
+    public void Dispose()
+    {
+        DisposePort();
+    }
+}