🩹 Fix ST7565 LCD contrast init (MarlinFirmware#24457)

Author: strnk

Marlin/Configuration.h

@@ -2631,6 +2631,12 @@
 //
 //#define SILVER_GATE_GLCD_CONTROLLER
 
+//
+// eMotion Tech LCD with SD
+// https://www.reprap-france.com/produit/1234568748-ecran-graphique-128-x-64-points-2-1
+//
+//#define EMOTION_TECH_LCD
+
 //=============================================================================
 //==============================  OLED Displays  ==============================
 //=============================================================================

Marlin/src/inc/Conditionals_LCD.h

@@ -99,7 +99,7 @@
   #define IS_ULTIPANEL 1
   #define STD_ENCODER_PULSES_PER_STEP 2
 
-#elif ANY(miniVIKI, VIKI2, WYH_L12864, ELB_FULL_GRAPHIC_CONTROLLER, AZSMZ_12864)
+#elif ANY(miniVIKI, VIKI2, WYH_L12864, ELB_FULL_GRAPHIC_CONTROLLER, AZSMZ_12864, EMOTION_TECH_LCD)
 
   #define DOGLCD
   #define IS_DOGM_12864 1
@@ -116,6 +116,9 @@
     #define IS_U8GLIB_LM6059_AF 1
   #elif ENABLED(AZSMZ_12864)
     #define IS_U8GLIB_ST7565_64128N 1
+  #elif ENABLED(EMOTION_TECH_LCD)
+    #define IS_U8GLIB_ST7565_64128N 1
+    #define ST7565_VOLTAGE_DIVIDER_VALUE 0x07
   #endif
 
 #elif ENABLED(OLED_PANEL_TINYBOY2)

Marlin/src/lcd/dogm/u8g_dev_st7565_64128n_HAL.cpp

@@ -74,7 +74,6 @@
 #define ST7565_ON(N)             ((N) ? 0xAF : 0xAE)
 #define ST7565_OUT_MODE(N)       ((N) ? 0xC8 : 0xC0)
 #define ST7565_POWER_CONTROL(N)  (0x28 | (N))
-#define ST7565_V0_RATIO(N)       (0x10 | ((N) & 0x7))
 #define ST7565_V5_RATIO(N)       (0x20 | ((N) & 0x7))
 #define ST7565_CONTRAST(N)       (0x81), (N)
 
@@ -106,11 +105,14 @@ static const uint8_t u8g_dev_st7565_64128n_HAL_init_seq[] PROGMEM = {
   ST7565_POWER_CONTROL(0x7),  // power control: turn on voltage follower
   U8G_ESC_DLY(50),            // delay 50 ms
 
-  ST7565_V0_RATIO(0),         // Set V0 voltage resistor ratio. Setting for controlling brightness of Displaytech 64128N
+  #ifdef ST7565_VOLTAGE_DIVIDER_VALUE
+                              // Set V5 voltage resistor ratio. Affects brightness of Displaytech 64128N
+    ST7565_V5_RATIO(ST7565_VOLTAGE_DIVIDER_VALUE),
+  #endif
 
   ST7565_INVERTED(0),         // display normal, bit val 0: LCD pixel off.
 
-  ST7565_CONTRAST(0x1E),      // Contrast value. Setting for controlling brightness of Displaytech 64128N
+  ST7565_CONTRAST(0x1E),      // Contrast value for Displaytech 64128N
 
   ST7565_ON(1),               // display on