We can tap cards and print their UIDs

AfRApay.FTM/AfRApay.FTM.csproj

@@ -7,4 +7,10 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="PCSC" Version="6.1.3" />
+    <PackageReference Include="PCSC.Iso7816" Version="6.1.3" />
+    <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />
+  </ItemGroup>
+
 </Project>

AfRApay.FTM/Program.cs

@@ -1,2 +1,79 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using System.CommandLine;
+using PCSC;
+using PCSC.Monitoring;
+using PCSC.Iso7816;
+
+var rootCommand = new RootCommand("Fancy Test Machine for AfRApay");
+
+var listReadersOption = new Option<bool>("--list-readers", "List card readers and exit");
+rootCommand.Add(listReadersOption);
+
+rootCommand.SetHandler((listReaders) => {
+    using (var context = ContextFactory.Instance.Establish(SCardScope.System)) {
+        // We need a card reader or this won't work!
+        var readerNames = context.GetReaders();
+        if (readerNames.Length == 0) {
+            Console.Error.WriteLine("Error: no card reader detected");
+            Environment.Exit(1);
+        }
+
+        // If --list-readers is passed, list readers and exit.
+        if (listReaders) {
+            Console.Error.WriteLine("---------- Connected Readers ----------");
+            foreach (var name in readerNames) {
+                Console.WriteLine(name);
+            }
+            Console.Error.WriteLine("---------------------------------------");
+            Environment.Exit(0);
+        }
+
+        // Listen for events on all connected readers.
+        using (var monitor = MonitorFactory.Instance.Create(SCardScope.System)) {
+            monitor.Initialized += (_, args) => Console.WriteLine("[ Reader Initialized: {0} ]", args.ReaderName);
+            monitor.MonitorException += (_, args) => {
+                Console.Error.WriteLine("! ERROR: {0}", args);
+                Environment.Exit(1);
+            };
+            monitor.StatusChanged += (_, args) => Console.WriteLine("~ {0} -> {1}", args.LastState, args.NewState);
+            monitor.CardInserted += (_, args) => {
+                Console.WriteLine("> TAP: {0}", Convert.ToHexString(args.Atr));
+                var reader = new IsoReader(context, args.ReaderName, SCardShareMode.Shared, SCardProtocol.Any);
+                HandleTap(reader);
+            };
+            monitor.CardRemoved += (_, args) => {
+                Console.WriteLine("< OFF");
+                Console.WriteLine(); // Write a blank line between card taps for readability.
+            };
+
+            Console.WriteLine("[ Starting... ]");
+            monitor.Start(readerNames);
+            while (true) {
+                Console.Read();
+            }
+        }
+    }
+}, listReadersOption);
+
+return await rootCommand.InvokeAsync(args);
+
+// Queries a card for data when one is tapped.
+static void HandleTap(IsoReader reader) {
+    // Send a PCSC pseudo-APDU to query the ISO 14443 UID.
+    var rsp = reader.Transmit(new CommandApdu(IsoCase.Case2Short, SCardProtocol.Any) {
+        CLA = 0xFF,
+        Instruction = InstructionCode.GetData,
+        P1 = 0x00,
+        P2 = 0x00,
+    });
+    if (!IsSucc(rsp)) {
+        Console.Error.WriteLine("--> Card Error: SW1={0} SW2={1}", (SW1Code)rsp.SW1, rsp.SW2);
+        return;
+    }
+    var uid = rsp.GetData();
+    Console.WriteLine("  UID: {0}", Convert.ToHexString(uid));
+}
+
+// Was the command successful?
+static bool IsSucc(Response rsp) {
+    return rsp.SW1 == (byte)SW1Code.Normal && rsp.SW2 == 0x00;
+}

shell.nix

@@ -3,8 +3,12 @@ pkgs.mkShell {
   name = "afrapay";
   packages = with pkgs; [
     dotnet-sdk_7
+    pcsclite
 
     # ESP32 tooling (for MateCard)
     platformio
   ];
+
+  # AfRApay.FTM tries to dlopen the pcsclite library at runtime.
+  LD_LIBRARY_PATH = [ "${pkgs.pcsclite.out}/lib" ];
 }