Added a light-weight status screen for the ST7920

- The status screen uses the ST7920 character generator to greatly
  reduce SPI traffic and MCU load when updating the status screen.

- Has been tested with the RepRapDiscount Full Graphics Smart Controller
  but should work with any LCD that uses an ST7920 or fully compatible
  controller.

Marlin/Configuration.h

@@ -1510,7 +1510,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/default/Configuration.h

@@ -1510,7 +1510,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/AliExpress/CL-260/Configuration.h

@@ -1510,7 +1510,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Anet/A6/Configuration.h

@@ -1658,9 +1658,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
-// Note: Details on connecting to the Anet V1.0 controller are in the file pins_ANET_10.h
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
 //
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Anet/A8/Configuration.h

@@ -1513,6 +1513,7 @@
 //
 //#define G3D_PANEL
 
+
 //
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
@@ -1521,6 +1522,18 @@
 //
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
 
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
+
 //
 // MakerLab Mini Panel with graphic
 // controller and SD support - http://reprap.org/wiki/Mini_panel

Marlin/src/config/examples/BIBO/TouchX/cyclops/Configuration.h

@@ -1510,7 +1510,18 @@ const bool Z_MIN_PROBE_ENDSTOP_INVERTING = true; // set to true to invert the lo
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/BIBO/TouchX/default/Configuration.h

@@ -1510,7 +1510,18 @@ const bool Z_MIN_PROBE_ENDSTOP_INVERTING = true; // set to true to invert the lo
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/FolgerTech/i3-2020/Configuration.h

@@ -1516,7 +1516,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Infitary/i3-M508/Configuration.h

@@ -1514,7 +1514,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/JGAurora/A5/Configuration.h

@@ -1521,7 +1521,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/RigidBot/Configuration.h

@@ -1512,6 +1512,18 @@
 //
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
 
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
+
 //
 // MakerLab Mini Panel with graphic
 // controller and SD support - http://reprap.org/wiki/Mini_panel

Marlin/src/config/examples/STM32F10/Configuration.h

@@ -1513,7 +1513,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Sanguinololu/Configuration.h

@@ -1541,7 +1541,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Tronxy/X1/Configuration.h

@@ -1495,7 +1495,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Tronxy/X5S/Configuration.h

@@ -1510,7 +1510,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Velleman/K8200/Configuration.h

@@ -1543,7 +1543,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Velleman/K8400/Configuration.h

@@ -1510,7 +1510,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/Velleman/K8400/Dual-head/Configuration.h

@@ -1504,7 +1504,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/delta/kossel_mini/Configuration.h

@@ -1634,7 +1634,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/gCreate/gMax1.5+/Configuration.h

@@ -1524,7 +1524,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 #define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/config/examples/makibox/Configuration.h

@@ -1513,7 +1513,18 @@
 // RepRapDiscount FULL GRAPHIC Smart Controller
 // http://reprap.org/wiki/RepRapDiscount_Full_Graphic_Smart_Controller
 //
+// If USE_ST7920_LIGHTWEIGHT_UI is uncommented, then an alternative
+// light-weight status screen will be used that takes advantage of
+// the ST7920 character-generator to conserve MCU resources.
+//
+// Since the lightweight status screen can only show a status
+// message or the position, but not both, set DELAY_TO_SHOW_POSITION
+// to the number of seconds until the position is revealed after a new
+// status message is drawn.
+
 //#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
+//#define USE_ST7920_LIGHTWEIGHT_UI
+//#define DELAY_TO_SHOW_POSITION 20
 
 //
 // MakerLab Mini Panel with graphic

Marlin/src/lcd/dogm/ultralcd_st7920_u8glib_rrd_AVR.cpp

@@ -119,10 +119,12 @@ uint8_t u8g_dev_rrd_st7920_128x64_fn(u8g_t *u8g, u8g_dev_t *dev, uint8_t msg, vo
       ST7920_CS();
       u8g_Delay(120);                 //initial delay for boot up
       ST7920_SET_CMD();
+      ST7920_WRITE_NIBBLES(0x20);       //non-extended mode
       ST7920_WRITE_NIBBLES(0x08);       //display off, cursor+blink off
-      ST7920_WRITE_NIBBLES(0x01);       //clear CGRAM ram
+      ST7920_WRITE_NIBBLES(0x01);       //clear DDRAM ram
-      u8g_Delay(15);                 //delay for CGRAM clear
+      u8g_Delay(15);                    //delay for DDRAM clear
-      ST7920_WRITE_NIBBLES(0x3E);       //extended mode + GDRAM active
+      ST7920_WRITE_NIBBLES(0x24);       //extended mode
+      ST7920_WRITE_NIBBLES(0x26);       //extended mode + GDRAM active
       for (y = 0; y < (LCD_PIXEL_HEIGHT) / 2; y++) { //clear GDRAM
         ST7920_WRITE_NIBBLES(0x80 | y); //set y
         ST7920_WRITE_NIBBLES(0x80);     //set x = 0
@@ -178,6 +180,14 @@ uint8_t   u8g_dev_st7920_128x64_rrd_buf[(LCD_PIXEL_WIDTH) * (PAGE_HEIGHT) / 8] U
 u8g_pb_t  u8g_dev_st7920_128x64_rrd_pb = {{PAGE_HEIGHT, LCD_PIXEL_HEIGHT, 0, 0, 0}, LCD_PIXEL_WIDTH, u8g_dev_st7920_128x64_rrd_buf};
 u8g_dev_t u8g_dev_st7920_128x64_rrd_sw_spi = {u8g_dev_rrd_st7920_128x64_fn, &u8g_dev_st7920_128x64_rrd_pb, &u8g_com_null_fn};
 
+#if ENABLED(USE_ST7920_LIGHTWEIGHT_UI)
+  typedef const __FlashStringHelper *progmem_str;
+
+  // We have to include the code for the lightweight UI here
+  // as it relies on macros that are only defined in this file.
+  #include "ultralcd_impl_st7920_lite_status_screen_impl_spi.h"
+#endif
+
 #pragma GCC reset_options
 
 #endif // U8G_HAL_LINKS

Marlin/src/lcd/ultralcd.cpp

@@ -5113,20 +5113,38 @@ void lcd_update() {
       #endif
 
       #if ENABLED(DOGLCD)
-        if (!drawing_screen) {                        // If not already drawing pages
+        #if defined(USE_ST7920_LIGHTWEIGHT_UI)
-          u8g.firstPage();                            // Start the first page
+          #if ENABLED(ULTIPANEL)
-          drawing_screen = 1;                         // Flag as drawing pages
+            bool do_U8G_loop = true;
-        }
+            lcd_in_status(currentScreen == lcd_status_screen);
-        lcd_setFont(FONT_MENU);                       // Setup font for every page draw
+            if(currentScreen == lcd_status_screen) {
-        u8g.setColorIndex(1);                         // And reset the color
+              lcd_status_screen();
-        CURRENTSCREEN();                              // Draw and process the current screen
+              do_U8G_loop = false;
+            }
+          #else
+            const bool do_U8G_loop = false;
+            lcd_in_status(true);
+            lcd_status_screen();
+          #endif
+        #else
+          const bool do_U8G_loop = true;
+        #endif
+        if(do_U8G_loop) {
+          if (!drawing_screen) {                        // If not already drawing pages
+            u8g.firstPage();                            // Start the first page
+            drawing_screen = 1;                         // Flag as drawing pages
+          }
+          lcd_setFont(FONT_MENU);                       // Setup font for every page draw
+          u8g.setColorIndex(1);                         // And reset the color
+          CURRENTSCREEN();                              // Draw and process the current screen
 
-        // The screen handler can clear drawing_screen for an action that changes the screen.
+          // The screen handler can clear drawing_screen for an action that changes the screen.
-        // If still drawing and there's another page, update max-time and return now.
+          // If still drawing and there's another page, update max-time and return now.
-        // The nextPage will already be set up on the next call.
+          // The nextPage will already be set up on the next call.
-        if (drawing_screen && (drawing_screen = u8g.nextPage())) {
+          if (drawing_screen && (drawing_screen = u8g.nextPage())) {
-          NOLESS(max_display_update_time, millis() - ms);
+            NOLESS(max_display_update_time, millis() - ms);
-          return;
+            return;
+          }
         }
       #else
         CURRENTSCREEN();

Marlin/src/lcd/ultralcd_impl_DOGM.h

@@ -54,6 +54,11 @@
 
 #include "dogm/dogm_bitmaps.h"
 
+#if ENABLED(USE_ST7920_LIGHTWEIGHT_UI)
+  typedef const __FlashStringHelper *progmem_str;
+  #include "dogm/ultralcd_impl_st7920_lite_status_screen_impl.h"
+#endif
+
 #if ENABLED(SDSUPPORT)
   #include "../libs/duration_t.h"
 #endif
@@ -373,6 +378,9 @@ static void lcd_implementation_init() {
 
 // The kill screen is displayed for unrecoverable conditions
 void lcd_kill_screen() {
+  #if ENABLED(USE_ST7920_LIGHTWEIGHT_UI)
+    ST7920_Lite_Status_Screen::clear_text_buffer();
+  #endif
   const uint8_t h4 = u8g.getHeight() / 4;
   u8g.firstPage();
   do {
@@ -498,6 +506,7 @@ inline void lcd_implementation_status_message(const bool blink) {
   #endif
 }
 
+#if !ENABLED(USE_ST7920_LIGHTWEIGHT_UI)
 static void lcd_implementation_status_screen() {
 
   const bool blink = lcd_blink();
@@ -803,6 +812,7 @@ static void lcd_implementation_status_screen() {
     #endif
   }
 }
+#endif
 
 #if ENABLED(ULTIPANEL)