Colorduino plasma demo, matrix test and browser simulator

- ColorduinoPlasma sketch and Colorduino library v1.2.6 (lincomatic @ fff7bd3)
- ColorduinoMatrixTest hardware test sketch
- web/index.html: bit-accurate port of the plasma with large resolutions
- prebuilt 16 MHz firmware (with and without Optiboot)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

arduino/ColorduinoMatrixTest/ColorduinoMatrixTest.ino

@@ -0,0 +1,111 @@
+/*
+  Colorduino 8x8 RGB matrix hardware test
+  Needs the Colorduino library (lincomatic).
+
+  Sequence (loops forever):
+    1. Full screen: RED, GREEN, BLUE, WHITE        -> dead colour channel / driver (DM163)
+    2. Rows one at a time (white)                  -> dead row driver (M54564)
+    3. Columns one at a time, R then G then B      -> dead column channel
+    4. Every LED one by one, R, G, B each          -> single dead / stuck LEDs
+    5. Brightness ramp 0..255 per colour            -> PWM / greyscale problems
+    6. Checkerboard + inverse                      -> shorts between neighbours
+
+  Note: Colorduino drives all of PORTD, so Serial cannot be used while it runs.
+*/
+
+#include <Colorduino.h>
+
+const uint8_t W = ColorduinoScreenWidth;
+const uint8_t H = ColorduinoScreenHeight;
+
+void show() { Colorduino.FlipPage(); }
+
+void fill(uint8_t r, uint8_t g, uint8_t b) {
+  Colorduino.ColorFill(r, g, b);   // ColorFill flips the page itself
+}
+
+void clearBuf() {
+  for (uint8_t y = 0; y < H; y++)
+    for (uint8_t x = 0; x < W; x++)
+      Colorduino.SetPixel(x, y, 0, 0, 0);
+}
+
+void fullColours() {
+  fill(255, 0, 0);   delay(1500);
+  fill(0, 255, 0);   delay(1500);
+  fill(0, 0, 255);   delay(1500);
+  fill(255, 255, 255); delay(1500);
+  fill(0, 0, 0);     delay(300);
+}
+
+void rowScan() {
+  for (uint8_t y = 0; y < H; y++) {
+    clearBuf();
+    for (uint8_t x = 0; x < W; x++) Colorduino.SetPixel(x, y, 255, 255, 255);
+    show();
+    delay(400);
+  }
+}
+
+void columnScan() {
+  const uint8_t cols[3][3] = {{255, 0, 0}, {0, 255, 0}, {0, 0, 255}};
+  for (uint8_t c = 0; c < 3; c++) {
+    for (uint8_t x = 0; x < W; x++) {
+      clearBuf();
+      for (uint8_t y = 0; y < H; y++)
+        Colorduino.SetPixel(x, y, cols[c][0], cols[c][1], cols[c][2]);
+      show();
+      delay(250);
+    }
+  }
+}
+
+void pixelWalk() {
+  for (uint8_t y = 0; y < H; y++) {
+    for (uint8_t x = 0; x < W; x++) {
+      clearBuf(); Colorduino.SetPixel(x, y, 255, 0, 0); show(); delay(120);
+      clearBuf(); Colorduino.SetPixel(x, y, 0, 255, 0); show(); delay(120);
+      clearBuf(); Colorduino.SetPixel(x, y, 0, 0, 255); show(); delay(120);
+    }
+  }
+}
+
+void ramps() {
+  for (uint8_t c = 0; c < 4; c++) {
+    for (int v = 0; v <= 255; v += 3) {
+      uint8_t r = (c == 0 || c == 3) ? v : 0;
+      uint8_t g = (c == 1 || c == 3) ? v : 0;
+      uint8_t b = (c == 2 || c == 3) ? v : 0;
+      fill(r, g, b);
+      delay(12);
+    }
+  }
+}
+
+void checker() {
+  for (uint8_t i = 0; i < 6; i++) {
+    for (uint8_t y = 0; y < H; y++)
+      for (uint8_t x = 0; x < W; x++) {
+        bool on = ((x + y + i) & 1);
+        Colorduino.SetPixel(x, y, on ? 255 : 0, on ? 255 : 0, on ? 255 : 0);
+      }
+    show();
+    delay(500);
+  }
+}
+
+void setup() {
+  Colorduino.Init();
+  // white balance (R, G, B), 0..63 - same default as the Plasma example
+  unsigned char whiteBal[3] = {36, 63, 63};
+  Colorduino.SetWhiteBal(whiteBal);
+}
+
+void loop() {
+  fullColours();
+  rowScan();
+  columnScan();
+  pixelWalk();
+  ramps();
+  checker();
+}