Merge pull request #486 from xifle/Marlin_v1

LCD: Added Deadzone at 100% Feedrate

Marlin/ultralcd.cpp

 static void menu_action_setting_edit_callback_float52(const char* pstr, float* ptr, float minValue, float maxValue, menuFunc_t callbackFunc);
 static void menu_action_setting_edit_callback_long5(const char* pstr, unsigned long* ptr, unsigned long minValue, unsigned long maxValue, menuFunc_t callbackFunc);
 
+#define ENCODER_FEEDRATE_DEADZONE 10
+
 #if !defined(LCD_I2C_VIKI)
   #define ENCODER_STEPS_PER_MENU_ITEM 5
 #else
   #define ENCODER_STEPS_PER_MENU_ITEM 2 // VIKI LCD rotary encoder uses a different number of steps per rotation
 #endif
 
+
 /* Helper macros for menus */
 #define START_MENU() do { \
     if (encoderPosition > 0x8000) encoderPosition = 0; \
     if (LCD_CLICKED)
     {
         currentMenu = lcd_main_menu;
+        encoderPosition = 0;
         lcd_quick_feedback();
     }
-    feedmultiply += int(encoderPosition);
-    encoderPosition = 0;
+
+    // Dead zone at 100% feedrate
+    if (feedmultiply < 100 && (feedmultiply + int(encoderPosition)) > 100 ||
+            feedmultiply > 100 && (feedmultiply + int(encoderPosition)) < 100)
+    {
+        encoderPosition = 0;
+        feedmultiply = 100;
+    }
+
+    if (feedmultiply == 100 && int(encoderPosition) > ENCODER_FEEDRATE_DEADZONE)
+    {
+        feedmultiply += int(encoderPosition) - ENCODER_FEEDRATE_DEADZONE;
+        encoderPosition = 0;
+    }
+    else if (feedmultiply == 100 && int(encoderPosition) < -ENCODER_FEEDRATE_DEADZONE)
+    {
+        feedmultiply += int(encoderPosition) + ENCODER_FEEDRATE_DEADZONE;
+        encoderPosition = 0;	
+    }
+    else if (feedmultiply != 100)
+    {
+        feedmultiply += int(encoderPosition);
+        encoderPosition = 0;
+    }
+
     if (feedmultiply < 10)
         feedmultiply = 10;
     if (feedmultiply > 999)