The **CFAG1602A-RFF-JP** is a specific character LCD module manufactured by Crystalfontz. This model belongs to the 16x2 character display family, characterized by its high-contrast Red-on-Black appearance. Below is a detailed breakdown of its electronic components and specifications. --- ### 1. General Specifications This display is a **STN (Super-Twisted Nematic)** negative display, meaning the pixels are transparent/lit while the background remains dark. | Feature | Specification | | :--- | :--- | | **Display Format** | 16 Characters x 2 Lines | | **LCD Type** | FSTN Negative, Transmissive | | **Backlight** | Red LED | | **Viewing Direction** | 6:00 | | **Interface** | 4-bit or 8-bit Parallel | | **Controller IC** | Sitronix ST7066U (or equivalent) | --- ### 2. Key Electronic Components #### A. The Controller (ST7066U) The heart of the module is the **ST7066U** dot-matrix LCD controller. It is industry-standard and compatible with the classic HD44780. * **Character Generator ROM (CGROM):** Contains the standard font map (the "JP" suffix often denotes a Japanese/Katakana font set). * **Character Generator RAM (CGRAM):** Allows the user to define up to 8 custom symbols or icons. * **Display Data RAM (DDRAM):** Stores the ASCII values of the characters currently shown on screen. #### B. The Backlight System The "RFF" in the part number indicates a **Red LED** backlight. * **Voltage:** Typically requires ~3.5V to 5.0V. * **Current:** Usually draws between 15mA and 60mA depending on brightness settings. * **Note:** A current-limiting resistor is often required on the Anode (Pin 15) to prevent burning out the LEDs. #### C. Power and Contrast The module requires two primary voltages: 1. **VDD (Logic):** Typically +5V (standard) or +3.3V (version dependent). 2. **V0 (Contrast):** An analog voltage input used to adjust the visibility of the characters. This is usually controlled via a **10kΩ Potentiometer** connected between VDD and Ground. --- ### 3. Pinout Configuration (Standard 16-Pin) | Pin | Symbol | Function | | :--- | :--- | :--- | | 1 | VSS | Ground (0V) | | 2 | VDD | Supply Voltage (+5V) | | 3 | V0 | Contrast Adjustment | | 4 | RS | Register Select (Command/Data) | | 5 | R/W | Read/Write Select | | 6 | E | Enable Signal | | 7-14 | DB0-DB7 | Data Bus (8-bit) | | 15 | A/LED+ | Backlight Anode (+) | | 16 | K/LED- | Backlight Cathode (-) | --- ### 4. Technical Considerations for Integration * **Initialization:** Upon power-up, the ST7066U requires a specific software initialization sequence (Function Set, Display ON/OFF, Entry Mode) before it can display text. * **Logic Levels:** If using a 3.3V microcontroller (like an ESP32 or STM32) with a 5V CFAG1602A, level shifters may be required for stable communication, though many units tolerate 3.3V logic for inputs. ---