Better MUX probe: 5 rounds, CLK before/after DI reads, single LED test

src/midi_transport.cpp

@@ -23,13 +23,21 @@ bool UsbMidiTransport::begin() {
     }
 
     initialized = true;
-    Serial.println("[MIDI] USB MIDI ready");
+    Serial.println("[MIDI] USB MIDI ready - enumerating...");
     return true;
 }
 
 void UsbMidiTransport::update() {
     if (!initialized) return;
 
+    static uint32_t last_status = 0;
+    uint32_t now = millis();
+    if (now - last_status > 5000) {
+        last_status = now;
+        Serial.printf("[MIDI] USB mounted: %s\n",
+                      TinyUSBDevice.mounted() ? "YES" : "NO");
+    }
+
     while (usb_midi.available()) {
         uint8_t packet[4];
         if (usb_midi.readPacket(packet)) {

src/pixel_stomp_mux.cpp

@@ -1,7 +1,7 @@
 #include "pixel_stomp_mux.h"
 #include <Arduino.h>
 
-#define ROXMUX_DELAY 1
+#define ROXMUX_DELAY 2
 
 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),
@@ -9,35 +9,41 @@ PixelStompMux::PixelStompMux(uint8_t dat, uint8_t ld, uint8_t clk, uint8_t di)
 }
 
 void PixelStompMux::begin() {
+    pinMode(pin_di, INPUT);
     pinMode(pin_clk, OUTPUT);
     pinMode(pin_ld, OUTPUT);
-    pinMode(pin_di, INPUT);
 
     digitalWrite(pin_clk, LOW);
     digitalWrite(pin_ld, HIGH);
 
-    FastLED.addLeds<WS2812, 9, GRB>(leds, NUM_LEDS);
-    FastLED.setBrightness(80);
+    delay(100);
+
+    FastLED.addLeds<WS2812B, 9, GRB>(leds, NUM_LEDS);
+    FastLED.setBrightness(128);
     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 (FastLED)\n", NUM_LEDS);
+    Serial.printf("[MUX] DI raw at init: %d\n", digitalRead(pin_di));
 }
 
 uint8_t PixelStompMux::read_buttons() {
+    digitalWrite(pin_clk, LOW);
+    delayMicroseconds(ROXMUX_DELAY);
+
     digitalWrite(pin_ld, LOW);
     delayMicroseconds(ROXMUX_DELAY);
     digitalWrite(pin_ld, HIGH);
+    delayMicroseconds(ROXMUX_DELAY);
 
     uint8_t data = 0;
     for (int i = 7; i >= 0; i--) {
+        digitalWrite(pin_clk, LOW);
+        delayMicroseconds(ROXMUX_DELAY);
         bitWrite(data, i, digitalRead(pin_di));
         digitalWrite(pin_clk, HIGH);
         delayMicroseconds(ROXMUX_DELAY);
-        digitalWrite(pin_clk, LOW);
-        delayMicroseconds(ROXMUX_DELAY);
     }
 
     last_button_state = data;
@@ -85,33 +91,43 @@ void PixelStompMux::dump() {
 
 void PixelStompMux::probe() {
     Serial.println("[MUX] === Hardware Probe ===");
-    Serial.printf("  DI (GPIO %d) raw: %d\n", pin_di, digitalRead(pin_di));
 
-    Serial.println("  Testing LD pin (RoxMux protocol)...");
-    digitalWrite(pin_ld, LOW);
-    delayMicroseconds(10);
-    Serial.printf("  LD=LOW,  DI=%d\n", digitalRead(pin_di));
+    for (int round = 0; round < 5; round++) {
+        Serial.printf("--- Round %d ---\n", round);
+
+        digitalWrite(pin_clk, LOW);
         digitalWrite(pin_ld, HIGH);
         delayMicroseconds(10);
-    Serial.printf("  LD=HIGH, DI=%d\n", digitalRead(pin_di));
 
-    Serial.println("  Toggling CLK 16 times, reading DI...");
+        Serial.printf("  Before latch: DI=%d\n", digitalRead(pin_di));
+
+        digitalWrite(pin_ld, LOW);
+        delayMicroseconds(10);
+        Serial.printf("  LD=LOW:       DI=%d\n", digitalRead(pin_di));
+
+        digitalWrite(pin_ld, HIGH);
+        delayMicroseconds(10);
+        Serial.printf("  LD=HIGH:      DI=%d\n", digitalRead(pin_di));
+
         for (int i = 0; i < 16; i++) {
-        bool bit = digitalRead(pin_di);
-        Serial.printf("  CLK %2d: DI=%d\n", i, bit);
-        digitalWrite(pin_clk, HIGH);
-        delayMicroseconds(5);
             digitalWrite(pin_clk, LOW);
             delayMicroseconds(5);
+            bool bit_before = digitalRead(pin_di);
+            digitalWrite(pin_clk, HIGH);
+            delayMicroseconds(5);
+            bool bit_after = digitalRead(pin_di);
+            Serial.printf("  CLK %2d: before=%d after=%d\n", i, bit_before, bit_after);
         }
 
-    Serial.println("  Testing FastLED DAT pin...");
-    fill_solid(leds, NUM_LEDS, CRGB::White);
+        delay(500);
+    }
+
+    Serial.println("  LED test: pixel 0 RED (max brightness)...");
+    leds[0] = CRGB(255, 0, 0);
     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);
+    leds[0] = CRGB::Black;
     FastLED.show();
 
     Serial.println("[MUX] === Probe Complete ===");