This is a simple tutorial on how to reuse old LCD boards from Ender 3's with a microcontroller such as arduino or teensy
The entire board can be controlled via the EXP3 10-pin connector The pinout on the EXP3 is as follows
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BEEPER |10 9 | ENC
EN1 | 8 7 | LCD_CS0(?)
EN2 6 5 | LCD_SCK
LCD_CS | 4 3 | LCD_MOSI
GND | 2 1 | 5V
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Note that pins 6, 8, and 9 are floating when true, so use a pullup resistor to get a clean input
The rotary encoder is standard incremental button/encoder and can be controlled with a library such as Encoder.h
The ENC
pin (9) is for the built-in encoder button
The Ender 3 LCD uses an ST7920 128x64 or equivalent driver.
A library, such as u8g2, can be used to control this
The LCD_SCK
(5) is used for clock, LCD_MOSI
(3) is used for data In/Out, and LCD_CS
(4) is for Chip Select/Register Select