From 71674059c3af806980a598590da894cee84217e1 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Sun, 10 Jul 2016 19:25:23 -0700
Subject: [PATCH 1/2] Two strategies to address a stuck buzzer

---
 Marlin/buzzer.h     | 2 +-
 Marlin/ultralcd.cpp | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Marlin/buzzer.h b/Marlin/buzzer.h
index c87fe849d7..04aadc4963 100644
--- a/Marlin/buzzer.h
+++ b/Marlin/buzzer.h
@@ -124,7 +124,7 @@ class Buzzer {
         this->state.timestamp = millis() + this->state.tone.duration;
         if (this->state.tone.frequency > 0) this->on();
       }
-      else if (millis() >= this->state.timestamp) this->reset();
+      else if (ELAPSED(millis(), this->state.timestamp)) this->reset();
     }
 };
 
diff --git a/Marlin/ultralcd.cpp b/Marlin/ultralcd.cpp
index d0a9a5dd73..5cd1252dbf 100755
--- a/Marlin/ultralcd.cpp
+++ b/Marlin/ultralcd.cpp
@@ -2334,12 +2334,14 @@ void kill_screen(const char* lcd_msg) {
     lcdDrawUpdate = LCDVIEW_CLEAR_CALL_REDRAW;
     next_button_update_ms = millis() + 500;
 
+    // Buzz and wait. The delay is needed for buttons to settle!
     #if ENABLED(LCD_USE_I2C_BUZZER)
       lcd.buzz(LCD_FEEDBACK_FREQUENCY_DURATION_MS, LCD_FEEDBACK_FREQUENCY_HZ);
+      delay(10);
     #elif PIN_EXISTS(BEEPER)
       buzzer.tone(LCD_FEEDBACK_FREQUENCY_DURATION_MS, LCD_FEEDBACK_FREQUENCY_HZ);
+      for (int8_t i = 5; i--;) { buzzer.tick(); delay(2); }
     #endif
-    delay(10); // needed for buttons to settle
   }
 
   /**

From d1dffc7ad10677052229124e0d8fd9f7f80744fb Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Sun, 10 Jul 2016 19:36:46 -0700
Subject: [PATCH 2/2] timestamp => endtime

---
 Marlin/buzzer.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/Marlin/buzzer.h b/Marlin/buzzer.h
index 04aadc4963..e967284eaa 100644
--- a/Marlin/buzzer.h
+++ b/Marlin/buzzer.h
@@ -46,7 +46,7 @@ class Buzzer {
   private:
     struct state_t {
       tone_t   tone;
-      uint32_t timestamp;
+      uint32_t endtime;
     } state;
 
   protected:
@@ -82,7 +82,7 @@ class Buzzer {
      */
     void reset() {
       this->off();
-      this->state.timestamp = 0;
+      this->state.endtime = 0;
     }
 
   public:
@@ -97,7 +97,7 @@ class Buzzer {
     /**
      * @brief Add a tone to the queue
      * @details Adds a tone_t structure to the ring buffer, will block IO if the
-     * queue is full waiting for one slot to get available.
+     *          queue is full waiting for one slot to get available.
      *
      * @param duration Duration of the tone in milliseconds
      * @param frequency Frequency of the tone in hertz
@@ -114,17 +114,17 @@ class Buzzer {
     /**
      * @brief Loop function
      * @details This function should be called at loop, it will take care of
-     * playing the tones in the queue.
+     *          playing the tones in the queue.
      */
     virtual void tick() {
-      if (!this->state.timestamp) {
+      if (!this->state.endtime) {
         if (this->buffer.isEmpty()) return;
 
         this->state.tone = this->buffer.dequeue();
-        this->state.timestamp = millis() + this->state.tone.duration;
+        this->state.endtime = millis() + this->state.tone.duration;
         if (this->state.tone.frequency > 0) this->on();
       }
-      else if (ELAPSED(millis(), this->state.timestamp)) this->reset();
+      else if (ELAPSED(millis(), this->state.endtime)) this->reset();
     }
 };