PD4 display test: cycle diagnostic patterns, not just all-on

The real display's power-on test (JP1 jumper 5, firmware $B888) runs through
several drawing sequences — a solid fill, a border+grid, more — each held
briefly, to expose dead dots and addressing faults; it isn't just full on/off.

Both vPLASMA and the replica firmware now cycle 5 representative patterns:
solid, border+grid, horizontal stripes, vertical stripes, checkerboard.
- VPlasmaDevice.ShowTestPattern(int) + TestPatternCount; the app cycles them
  on a 1.2s timer while jumper 5 is installed.
- PlasmaDisplay::showTestPattern(int) + TEST_PATTERN_COUNT (shared logic); the
  Matrix Portal sketch's DOWN button toggles the cycling test.

(The firmware's exact byte patterns live in the display's native scan-buffer
layout, which we haven't mapped, so these stand in for that sequence rather
than reproducing it byte-for-byte.)

Verified: 29 C# tests pass; the C++ patterns render distinctly on the host.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

PlasmaNew/replica/MatrixPortalPlasma/MatrixPortalPlasma.ino

@@ -47,6 +47,12 @@ static int demoScreen = 0;
 static uint32_t lastDemoStep = 0;
 static const uint32_t DEMO_MS = 2800;
 
+// Panel test (DOWN button): cycle the diagnostic patterns.
+static bool testRunning = false;
+static int testPattern = 0;
+static uint32_t lastTestStep = 0;
+static const uint32_t TEST_MS = 1200;
+
 // ---- helpers -------------------------------------------------------------
 
 static bool frameHasFlash = false;
@@ -120,6 +126,7 @@ void loop() {
   bool up = digitalRead(BUTTON_UP);
   if (upPrev == HIGH && up == LOW) {  // pressed
     demoRunning = !demoRunning;
+    testRunning = false;
     if (demoRunning) { demoScreen = 0; feedDemoScreen(0); demoScreen = 1; lastDemoStep = millis(); }
     else { display.reset(); }
   }
@@ -129,19 +136,26 @@ void loop() {
   static bool downPrev = HIGH;
   bool down = digitalRead(BUTTON_DOWN);
   if (downPrev == HIGH && down == LOW) {  // pressed
+    testRunning = !testRunning;
     demoRunning = false;
-    display.showTestPattern();
+    if (testRunning) { testPattern = 0; display.showTestPattern(0); lastTestStep = millis(); }
+    else { display.reset(); }
   }
   downPrev = down;
 #endif
 
-  // 3) Advance the demo on its timer.
+  // 3) Advance the demo / test on their timers.
   uint32_t now = millis();
   if (demoRunning && now - lastDemoStep >= DEMO_MS) {
     feedDemoScreen(demoScreen);
     demoScreen = (demoScreen + 1) % plasmaDemoCount;
     lastDemoStep = now;
   }
+  if (testRunning && now - lastTestStep >= TEST_MS) {
+    testPattern = (testPattern + 1) % PlasmaDisplay::TEST_PATTERN_COUNT;
+    display.showTestPattern(testPattern);
+    lastTestStep = now;
+  }
 
   // 4) Blink phase for flashing pixels.
   if (now - lastBlink >= BLINK_MS) {

PlasmaNew/replica/MatrixPortalPlasma/PlasmaDisplay.cpp

@@ -32,8 +32,25 @@ void PlasmaDisplay::setOrientation(Orientation o) {
   dirty_ = true;
 }
 
-void PlasmaDisplay::showTestPattern() {
-  for (int i = 0; i < WIDTH * HEIGHT; ++i) pixels_[i] = PIX_LIT;
+// The real display's power-on test (JP1 jumper 5, firmware $B888) runs through
+// several drawing sequences — solid, border+grid, and more — to expose dead
+// dots and addressing faults. These stand in for that; the sketch cycles them.
+static bool testDot(int index, int x, int y) {
+  switch (index) {
+    case 0: return true;                                                // all on
+    case 1: return x == 0 || x == PlasmaDisplay::WIDTH - 1 ||           // frame
+                   y == 0 || y == PlasmaDisplay::HEIGHT - 1 ||
+                   (x % 16) == 0 || (y % 8) == 0;                        // + grid
+    case 2: return ((y / 2) % 2) == 0;                                  // horizontal stripes
+    case 3: return ((x / 4) % 2) == 0;                                  // vertical stripes
+    default: return (((x / 8) + (y / 8)) % 2) == 0;                     // checkerboard
+  }
+}
+
+void PlasmaDisplay::showTestPattern(int index) {
+  for (int y = 0; y < HEIGHT; ++y)
+    for (int x = 0; x < WIDTH; ++x)
+      pixels_[y * WIDTH + x] = testDot(index, x, y) ? PIX_LIT : 0;
   dirty_ = true;
 }
 

PlasmaNew/replica/MatrixPortalPlasma/PlasmaDisplay.h

@@ -25,10 +25,13 @@ class PlasmaDisplay {
 
   PlasmaDisplay();
 
+  static const int TEST_PATTERN_COUNT = 5;  // JP1 jumper-5 diagnostic patterns
+
   void reset();                        // power-on: dark glass, home cursor
   void feed(uint8_t b);                // one received wire byte
   void feed(const uint8_t *buf, size_t n);
-  void showTestPattern();              // all dots lit (JP1 jumper 5)
+  void showTestPattern() { showTestPattern(0); }  // all dots lit
+  void showTestPattern(int index);     // JP1 jumper 5: solid/grid/stripes/checker
   void setOrientation(Orientation o);  // JP1 jumper 4
 
   const uint8_t *frame() const { return pixels_; }

PlasmaNew/replica/README.md

@@ -66,7 +66,9 @@ display listens), exactly as the cockpit drove the real panel.
 
 - **UP** — toggle the built-in **firmware demonstration** (the real 10-screen
   PLASMADOT demo, `demo_screens.h`, extracted from the ROM).
-- **DOWN** — the **panel test pattern** (all dots lit; a dead-dot check).
+- **DOWN** — toggle the **panel test**: cycles diagnostic patterns (solid,
+  border+grid, horizontal/vertical stripes, checkerboard) to expose dead dots
+  and addressing faults — the multi-pattern sequence the real firmware runs.
 - **Power-on** briefly lights every dot (confirms both panels), then clears.
 
 ## Files

src/VPlasma.App/MainForm.cs

@@ -30,8 +30,10 @@ internal sealed class MainForm : Form
 
     private readonly System.Windows.Forms.Timer _uiTimer = new() { Interval = 500 };
     private readonly System.Windows.Forms.Timer _demoTimer = new() { Interval = 2800 };
+    private readonly System.Windows.Forms.Timer _testTimer = new() { Interval = 1200 };
     private int _selfTestPage;
     private int _demoScreen;
+    private int _testPattern;
 
     // ---- config panel controls -------------------------------------------
     private readonly ComboBox _portBox = new() { Width = 168, DropDownStyle = ComboBoxStyle.DropDownList };
@@ -118,6 +120,7 @@ internal sealed class MainForm : Form
         _jp5.CheckedChanged += (_, _) => ApplyTestPattern();
         _jp6.CheckedChanged += (_, _) => ApplyDemo();
         _demoTimer.Tick += (_, _) => StepDemo();
+        _testTimer.Tick += (_, _) => StepTestPattern();
 
         // Default straps: jumper 2 installed = 9600 (the game's rate). Jumper 4
         // unstrapped = horizontal (the normal cockpit orientation).
@@ -130,6 +133,7 @@ internal sealed class MainForm : Form
         {
             _uiTimer.Dispose();
             _demoTimer.Dispose();
+            _testTimer.Dispose();
             _service.Dispose();
             _pipeService.Dispose();
         };
@@ -288,16 +292,25 @@ internal sealed class MainForm : Form
     {
         if (_jp5.Checked)
         {
-            _device.ShowTestPattern();
-            PrependLog("Jumper 5 installed — panel test pattern (all dots lit)");
+            PrependLog("Jumper 5 installed — panel test (cycling diagnostic patterns)");
+            _testPattern = 0;
+            _device.ShowTestPattern(0);
+            _testTimer.Start();
         }
         else
         {
+            _testTimer.Stop();
             _device.Reset();
             PrependLog("Jumper 5 removed — test pattern cleared");
         }
     }
 
+    private void StepTestPattern()
+    {
+        _testPattern = (_testPattern + 1) % VPlasmaDevice.TestPatternCount;
+        _device.ShowTestPattern(_testPattern);
+    }
+
     private void ApplyDemo()
     {
         if (_jp6.Checked)

src/VPlasma.Core/Device/VPlasmaDevice.cs

@@ -197,21 +197,41 @@ public sealed class VPlasmaDevice
         FlushEvents();
     }
 
+    /// <summary>Number of diagnostic patterns the JP1 jumper-5 test cycles.</summary>
+    public const int TestPatternCount = 5;
+
+    /// <summary>Show the first test pattern (all dots lit).</summary>
+    public void ShowTestPattern() => ShowTestPattern(0);
+
     /// <summary>
-    /// Light every dot — the panel test pattern JP1 jumper 5 runs at power-on
-    /// (the firmware's dead-dot check). Clear it with <see cref="Reset"/>.
+    /// Paint diagnostic pattern <paramref name="index"/> (0..<see
+    /// cref="TestPatternCount"/>-1). The real display's power-on test (JP1
+    /// jumper 5, firmware <c>$B888</c>) runs through several drawing
+    /// sequences — a solid fill, a border+grid, and more, each held briefly —
+    /// to expose dead dots and addressing faults; these stand in for that.
     /// </summary>
-    public void ShowTestPattern()
+    public void ShowTestPattern(int index)
     {
         lock (_sync)
         {
-            for (int i = 0; i < _pixels.Length; ++i)
-                _pixels[i] = PixelLit;
+            for (int y = 0; y < Height; ++y)
+                for (int x = 0; x < Width; ++x)
+                    _pixels[y * Width + x] = TestDot(index, x, y) ? PixelLit : (byte)0;
             _dirty = true;
         }
         FlushEvents();
     }
 
+    private static bool TestDot(int index, int x, int y) => index switch
+    {
+        0 => true,                                                       // all on
+        1 => x == 0 || x == Width - 1 || y == 0 || y == Height - 1       // frame
+             || x % 16 == 0 || y % 8 == 0,                               // + grid
+        2 => (y / 2) % 2 == 0,                                           // horizontal stripes
+        3 => (x / 4) % 2 == 0,                                           // vertical stripes
+        _ => ((x / 8) + (y / 8)) % 2 == 0,                              // checkerboard
+    };
+
     /// <summary>Feed <paramref name="count"/> received wire bytes.</summary>
     public void OnReceived(byte[] buffer, int count)
     {