The **PC12864B-FNMSD** is a specific model of a monochrome Graphic Liquid Crystal Display (GLCD). It is widely used in industrial equipment, medical devices, and DIY electronics due to its ability to display both text and complex bitmaps. --- ## 1. Technical Specifications The part number follows a standard convention for 128x64 dot matrix displays. Below are the primary electronic characteristics: | Parameter | Specification | | :--- | :--- | | **Resolution** | 128 x 64 Pixels | | **Controller IC** | Typically **KS0108** or **ST7920** (Check datasheet for variant) | | **Logic Voltage (VDD)** | +5.0V (Standard) or +3.3V (Optional) | | **LCD Drive Voltage (V0)** | Variable (Requires a potentiometer for contrast) | | **Backlight Type** | LED (Sidelight or Bottom light) | | **Interface** | 8-bit Parallel | | **Display Mode** | STN (Super-Twisted Nematic) | --- ## 2. Pinout Configuration The PC12864B typically utilizes a 20-pin interface. Understanding these pins is crucial for hardware integration: | Pin No. | Symbol | Function | | :--- | :--- | :--- | | 1 | **VSS** | Ground (0V) | | 2 | **VDD** | Power supply for Logic (+5V) | | 3 | **V0** | Contrast Adjustment | | 4 | **D/I (RS)** | Data/Instruction Register Select | | 5 | **R/W** | Read/Write Select | | 6 | **E** | Enable Signal | | 7-14 | **DB0-DB7** | Data Bus (8-bit) | | 15 | **CS1** | Chip Select 1 (Controls left half of screen) | | 16 | **CS2** | Chip Select 2 (Controls right half of screen) | | 17 | **RST** | Reset Signal | | 18 | **VEE** | Negative Voltage Output (For contrast circuit) | | 19 | **A (LED+)** | Backlight Anode (+5V) | | 20 | **K (LED-)** | Backlight Cathode (GND) | --- ## 3. Electronic Driving Logic To operate this module, the electronic circuit must manage the following: ### A. Contrast Circuit The module includes a **VEE** pin which outputs a negative voltage (approx. -10V). To adjust the visibility of the pixels, you must connect a 10k-20k Ohm potentiometer between **VDD** and **VEE**, with the wiper connected to **V0**. ### B. Chip Selection (CS1/CS2) Because the internal controller (like the KS0108) can only handle 64x64 pixels, the 128x64 display is electronically split into two halves. - To write to the left side, **CS1** must be pulled high. - To write to the right side, **CS2** must be pulled high. ### C. Example Connection (Arduino/C++) If using an Arduino, you would typically use the `u8glib` or `U8g2` library. ```cpp // Example constructor for a KS0108-based 128x64 display // U8G2_KS0108_128X64_1(rotation, d0, d1, d2, d3, d4, d5, d6, d7, en, cs1, cs2, di, rw, reset) U8G2_KS0108_128X64_1 u8g2(U8G2_R0, 8, 9, 10, 11, 4, 5, 6, 7, 18, 14, 15, 17, 16, 19); ``` --- ## 4. Optical Characteristics * **F-N-M-S-D Suffixes:** * **F:** Usually indicates FSTN or STN-Film type (High contrast). * **N:** No Temperature Compensation circuit. * **M:** Transflective (Visible under sunlight and with backlight). * **S:** Standard Temperature range (0°C to +50°C). * **D:** Often refers to the specific LED backlight color (usually Yellow-Green or White).