Switch from NeoPixel to FastLED for ESP32-S3 LED reliability

FastLED has better ESP32 support and handles timing/RMT properly.
- Use CRGB array instead of Adafruit_NeoPixel
- FastLED.show() is more reliable on ESP32-S3
- probe command now tests all LEDs at max brightness

src/led_stub.cpp

@@ -19,7 +19,7 @@ void DefaultLedStub::set_mux(PixelStompMux* mux) {
 }
 
 void DefaultLedStub::begin() {
-    Serial.println("[LED] Using WS2812C via PixelStomp MUX");
+    Serial.println("[LED] Using WS2812C via PixelStomp MUX (FastLED)");
     initialized = true;
 
     if (!mux_ptr) {
@@ -30,13 +30,13 @@ void DefaultLedStub::begin() {
     Serial.println("[LED] Startup animation...");
 
     uint32_t colors[] = {
-        0xFF0000,  // Red
-        0x00FF00,  // Green
-        0x0000FF,  // Blue
-        0xFFFF00,  // Yellow
-        0xFF00FF,  // Magenta
-        0x00FFFF,  // Cyan
-        0xFFFFFF,  // White
+        0xFF0000,
+        0x00FF00,
+        0x0000FF,
+        0xFFFF00,
+        0xFF00FF,
+        0x00FFFF,
+        0xFFFFFF,
     };
     int num_colors = sizeof(colors) / sizeof(colors[0]);
 
@@ -51,7 +51,7 @@ void DefaultLedStub::begin() {
         }
         mux_ptr->show();
         Serial.printf("[LED] Colour %d: R=%d G=%d B=%d\n", c, r, g, b);
-        delay(200);
+        delay(300);
     }
 
     clear_all();
@@ -71,15 +71,15 @@ void DefaultLedStub::set_led_state(uint8_t note, uint8_t channel, uint8_t veloci
         led_states[led_index].timestamp = millis();
 
         if (velocity > 0) {
-            uint8_t brightness = map(velocity, 1, 127, 30, 255);
+            uint8_t brightness = map(velocity, 1, 127, 50, 255);
             mux_ptr->set_led_color(led_index, brightness, brightness, brightness);
         } else {
             mux_ptr->set_led_color(led_index, 0, 0, 0);
         }
         mux_ptr->show();
         
-        Serial.printf("[LED] Note %d -> LED %d Ch %d Vel %d (%s)\n",
-                      note, led_index, channel, velocity,
+        Serial.printf("[LED] Note %d -> LED %d Vel %d (%s)\n",
+                      note, led_index, velocity,
                       velocity > 0 ? "ON" : "OFF");
     } else {
         Serial.printf("[LED] Out of range: %d (Note: %d)\n", led_index, note);

src/pixel_stomp_mux.cpp

@@ -5,7 +5,7 @@
 
 PixelStompMux::PixelStompMux(uint8_t dat, uint8_t ld, uint8_t clk, uint8_t di)
     : pin_dat(dat), pin_ld(ld), pin_clk(clk), pin_di(di),
-      strip(nullptr), last_button_state(0) {
+      last_button_state(0) {
 }
 
 void PixelStompMux::begin() {
@@ -16,15 +16,14 @@ void PixelStompMux::begin() {
     digitalWrite(pin_clk, LOW);
     digitalWrite(pin_ld, HIGH);
 
-    strip = new Adafruit_NeoPixel(NUM_LEDS, pin_dat, NEO_GRB + NEO_KHZ800);
-    strip->begin();
-    strip->setBrightness(80);
-    strip->clear();
-    strip->show();
+    FastLED.addLeds<WS2812, 9, GRB>(leds, NUM_LEDS);
+    FastLED.setBrightness(80);
+    fill_solid(leds, NUM_LEDS, CRGB::Black);
+    FastLED.show();
 
     Serial.printf("[MUX] Init DAT=%d LD=%d CLK=%d DI=%d\n",
                   pin_dat, pin_ld, pin_clk, pin_di);
-    Serial.printf("[MUX] 74HC165 x2 daisy-chain, WS2812C x%d LEDs\n", NUM_LEDS);
+    Serial.printf("[MUX] 74HC165 x2 daisy-chain, WS2812C x%d LEDs (FastLED)\n", NUM_LEDS);
 }
 
 uint8_t PixelStompMux::read_buttons() {
@@ -52,24 +51,22 @@ bool PixelStompMux::is_button_pressed(uint8_t index) {
 }
 
 void PixelStompMux::set_led_color(uint8_t index, uint8_t r, uint8_t g, uint8_t b) {
-    if (index >= NUM_LEDS || !strip) return;
-    strip->setPixelColor(index, strip->Color(r, g, b));
+    if (index >= NUM_LEDS) return;
+    leds[index] = CRGB(r, g, b);
 }
 
 void PixelStompMux::set_led_brightness(uint8_t brightness) {
-    if (strip) strip->setBrightness(brightness);
+    FastLED.setBrightness(brightness);
 }
 
 void PixelStompMux::clear_all() {
-    if (strip) {
-        strip->clear();
-        strip->show();
-    }
+    fill_solid(leds, NUM_LEDS, CRGB::Black);
+    FastLED.show();
     Serial.println("[MUX] LEDs cleared");
 }
 
 void PixelStompMux::show() {
-    if (strip) strip->show();
+    FastLED.show();
 }
 
 void PixelStompMux::dump() {
@@ -108,15 +105,14 @@ void PixelStompMux::probe() {
         delayMicroseconds(5);
     }
 
-    Serial.println("  Testing NeoPixel DAT pin...");
-    if (strip) {
-        strip->setPixelColor(0, strip->Color(255, 255, 255));
-        strip->show();
-        Serial.println("  Set pixel 0 to WHITE - check if it lights up");
-        delay(1000);
-        strip->clear();
-        strip->show();
-    }
+    Serial.println("  Testing FastLED DAT pin...");
+    fill_solid(leds, NUM_LEDS, CRGB::White);
+    FastLED.setBrightness(255);
+    FastLED.show();
+    Serial.println("  All pixels WHITE (max brightness) - check if they light up");
+    delay(2000);
+    fill_solid(leds, NUM_LEDS, CRGB::Black);
+    FastLED.show();
 
     Serial.println("[MUX] === Probe Complete ===");
 }