📺 Melzi v4 with BTT SKR Mini E3 (MarlinFirmware#25321)

Author: kg333

Marlin/src/pins/stm32f1/pins_BTT_SKR_MINI_E3_common.h

@@ -163,15 +163,46 @@
   #if ENABLED(CR10_STOCKDISPLAY)
 
     #define BEEPER_PIN               EXP1_01_PIN
-    #define BTN_ENC                  EXP1_02_PIN
 
+    #define BTN_ENC                  EXP1_02_PIN
     #define BTN_EN1                  EXP1_03_PIN
     #define BTN_EN2                  EXP1_05_PIN
 
     #define LCD_PINS_RS              EXP1_07_PIN
     #define LCD_PINS_ENABLE          EXP1_08_PIN
     #define LCD_PINS_D4              EXP1_06_PIN
 
+  #elif ENABLED(LCD_FOR_MELZI)
+
+    #ifndef NO_CONTROLLER_CUSTOM_WIRING_WARNING
+      #error "CAUTION! LCD for Melzi v4 display requires a custom cable. See 'pins_BTT_SKR_MINI_E3_common.h' for details. (Define NO_CONTROLLER_CUSTOM_WIRING_WARNING to suppress this warning.)"
+    #endif
+
+    /**
+     * LCD for Melzi v4 needs a custom cable with reversed GND/5V pins; plugging in a standard cable may damage the board or LCD!
+     *  1. Swap the LCD's +5V (Pin2) and GND (Pin1) wires. (This is the critical part!)
+     *  2. Swap pin 4 on the Melzi LCD to pin 7 on the SKR Mini E3 EXP1 connector (pin 4 on the SKR is a RESET and cannot be used)
+     *
+     *       LCD for Melzi V4         SKR Mini E3 V2.0
+     *            ------                   ------
+     *    LCD RS | 1  2 | EN1      LCD RS | 1  2 | EN1
+     *    LCD EN | 3  4 | EN2      LCD EN | 3  4 | OPEN (RESET)
+     *    LCD D4 | 5  6 | ENC      LCD D4 | 5  6 | ENC
+     *    E-Stop | 7  8 | BEEP        EN2 | 7  8 | BEEP
+     *        5V | 9 10 | GND         GND | 9 10 | 5V
+     *            ------                   ------
+     *             EXP1                     EXP1
+     */
+    #define BEEPER_PIN               EXP1_08_PIN
+
+    #define BTN_ENC                  EXP1_06_PIN
+    #define BTN_EN1                  EXP1_02_PIN
+    #define BTN_EN2                  EXP1_07_PIN
+
+    #define LCD_PINS_RS              EXP1_01_PIN
+    #define LCD_PINS_ENABLE          EXP1_03_PIN
+    #define LCD_PINS_D4              EXP1_05_PIN
+
   #elif ENABLED(ZONESTAR_LCD)                     // ANET A8 LCD Controller - Must convert to 3.3V - CONNECTING TO 5V WILL DAMAGE THE BOARD!
 
     #ifndef NO_CONTROLLER_CUSTOM_WIRING_WARNING
@@ -306,7 +337,7 @@
     #define FORCE_SOFT_SPI
 
   #else
-    #error "Only CR10_STOCKDISPLAY, ZONESTAR_LCD, ENDER2_STOCKDISPLAY, MKS_MINI_12864, TFTGLCD_PANEL_(SPI|I2C), FYSETC_MINI_12864_2_1, MKS_MINI_12864_V3, and BTT_MINI_12864_V1 are currently supported on the BIGTREE_SKR_MINI_E3."
+    #error "Only CR10_STOCKDISPLAY, LCD_FOR_MELZI, ZONESTAR_LCD, ENDER2_STOCKDISPLAY, MKS_MINI_12864, TFTGLCD_PANEL_(SPI|I2C), FYSETC_MINI_12864_2_1, MKS_MINI_12864_V3, and BTT_MINI_12864_V1 are currently supported on the BIGTREE_SKR_MINI_E3."
   #endif
 
 #endif // HAS_WIRED_LCD