workaround for issue #3128

wled00/wled.cpp

@@ -267,6 +267,9 @@ void WLED::setup()
   WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0); //disable brownout detection
   #endif
 
+  #ifdef ARDUINO_ARCH_ESP32
+  pinMode(hardwareRX, INPUT_PULLDOWN); delay(1);        // suppress noise in case RX pin is floating (at low noise energy) - see issue #3128
+  #endif
   Serial.begin(115200);
   #if !ARDUINO_USB_CDC_ON_BOOT
   Serial.setTimeout(50);  // this causes troubles on new MCUs that have a "virtual" USB Serial (HWCDC)

wled00/wled.h

@@ -8,7 +8,7 @@
  */
 
 // version code in format yymmddb (b = daily build)
-#define VERSION 2303050
+#define VERSION 2303160
 
 //uncomment this if you have a "my_config.h" file you'd like to use
 //#define WLED_USE_MY_CONFIG

wled00/wled_serial.cpp

@@ -70,6 +70,7 @@ void sendBytes(){
 void handleSerial()
 {
   if (pinManager.isPinAllocated(hardwareRX)) return;
+  if (!Serial) return;              // arduino docs: `if (Serial)` indicates whether or not the USB CDC serial connection is open. For all non-USB CDC ports, this will always return true
 
   #ifdef WLED_ENABLE_ADALIGHT
   static auto state = AdaState::Header_A;