This is an adapter to free pins 16 and 17 on the RAMPS AUX-4 connector usually used for LCDs to be used for the MMU2 serial connection. The LCD I use is the Anet 12864 LCD Smart Display Controller. Other LCDs might work but I can't guarantee for that.
To use the Anet LCD with this adapter you have to set the following configuration options in Marlin.
#define REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
At the end of the file add
// custom pins ANET LCD 12864
#undef LCD_PINS_RS
#undef LCD_PINS_ENABLE
#undef LCD_PINS_D4
#undef LCD_PINS_D5
#undef LCD_PINS_D6
#undef LCD_PINS_D7
#undef BEEPER_PIN
#define LCD_PINS_RS 25
#define LCD_PINS_ENABLE 27
#define LCD_PINS_D4 29
#define LCD_PINS_D5 -1
#define LCD_PINS_D6 -1
#define LCD_PINS_D7 -1
#define BEEPER_PIN 37
#define STD_ENCODER_PULSES_PER_STEP 4
#define STD_ENCODER_STEPS_PER_MENU_ITEM 1
//#define ST7920_DELAY_1 DELAY_1_NOP
//#define ST7920_DELAY_2 DELAY_2_NOP
//#define ST7920_DELAY_3 DELAY_3_NOP
#define ST7920_DELAY_1 DELAY_NS(0)
#define ST7920_DELAY_2 DELAY_NS(63)
#define ST7920_DELAY_3 DELAY_NS(125)
The MMU2 connector has the following pins from top to bottom (colors correspond to the original Prusa MMU2 serial cable):
- +5V (Blue)
- TX (White)
- RX (Green)
- NC
- Hardware Reset (Brown)