🔧 Sanity-check AVR D9 Fan PWM / SPEAKER Timer2 (#23672)

Marlin/src/HAL/AVR/inc/SanityCheck.h

@@ -29,7 +29,15 @@
  * Checks for FAST PWM
  */
 #if ALL(FAST_PWM_FAN, USE_OCR2A_AS_TOP, HAS_TCCR2)
-  #error "USE_OCR2A_AS_TOP does not apply to devices with a single output TIMER2"
+  #error "USE_OCR2A_AS_TOP does not apply to devices with a single output TIMER2."
+#endif
+
+/**
+ * Checks for SOFT PWM
+ */
+#if HAS_FAN0 && FAN_PIN == 9 && DISABLED(FAN_SOFT_PWM) && ENABLED(SPEAKER)
+  #error "FAN_PIN 9 Hardware PWM uses Timer 2 which conflicts with Arduino AVR Tone Timer (for SPEAKER)."
+  #error "Disable SPEAKER or enable FAN_SOFT_PWM."
 #endif
 
 /**

Marlin/src/inc/SanityCheck.h

@@ -2018,7 +2018,7 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
   #if CONTROLLER_FAN_PIN == FAN_PIN
     #error "You cannot set CONTROLLER_FAN_PIN equal to FAN_PIN."
   #elif ENABLED(FAN_SOFT_PWM_REQUIRED) && DISABLED(FAN_SOFT_PWM)
-    #error "FAN_SOFT_PWM is required. Enable it to continue."
+    #error "FAN_SOFT_PWM is required for your board. Enable it to continue."
   #endif
 #endif