## Overview of the BT817Q-R The **BT817Q-R** is a high-performance Embedded Video Engine (EVE) chip manufactured by Bridgetek (formerly FTDI Chip). It is part of the EVE4 generation, designed to simplify the creation of advanced Human Machine Interfaces (HMI) by offloading graphics processing from a system microcontroller (MCU). --- ### Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Generation** | EVE4 | | **Max Resolution** | 1280 x 800 pixels | | **Video Interface** | RGB (up to 24-bit parallel) | | **Host Interface** | SPI, Dual SPI, or Quad SPI (up to 30MHz) | | **On-chip RAM** | 1 MB (Graphics RAM) | | **Flash Support** | Dedicated SPI Master for external Flash (up to 256MB) | | **Audio Support** | Built-in sound synthesizer + mono audio output | | **Package** | VQFN-64 | --- ### Core Functional Blocks #### 1. Graphics Engine The BT817Q-R treats graphics as a "Display List." Instead of the MCU calculating every pixel, the MCU sends high-level commands (e.g., `DRAW_CIRCLE`), and the BT817 renders it line-by-line. * **ASTC Compression:** Supports Adaptive Scalable Texture Compression, allowing for high-quality images with low memory footprints. * **Animation Support:** Built-in support for video playback (MJPEG). #### 2. Touch Controller Interface The "Q" in BT817Q-R signifies **Capacitive Touch** support. * It acts as an I2C master to communicate directly with external capacitive touch screen controllers (like those from Goodix or FocalTech). * It tracks up to 5 simultaneous touch points. #### 3. Flash Memory Interface Unlike previous generations, EVE4 chips include a dedicated high-speed SPI port to fetch assets (images, fonts, animations) directly from external Flash memory, bypassing the MCU to ensure smooth performance at higher resolutions. --- ### Comparison: BT817 vs. Previous Generations | Feature | BT815/816 (EVE3) | BT817/818 (EVE4) | | :--- | :--- | :--- | | **Max Pixels** | 800 x 600 | 1280 x 800 | | **Large Font Support** | Limited | Extended (Unicode) | | **Clock Speed** | 60 MHz | 72 MHz | | **Video Output** | 18-bit | 24-bit | --- ### Typical Application Circuitry To implement the BT817Q-R in a design, you generally need the following external components: ```c // High-level Block Diagram [MCU] <---(QSPI)---> [BT817Q-R] <---(RGB)---> [LCD Panel] | | [External Flash] [Touch IC] ``` 1. **Oscillator:** Requires a 12MHz crystal or external clock. 2. **Power Supply:** Operates at 3.3V, but internal cores often require 1.2V (usually generated by an internal LDO with external decoupling capacitors). 3. **Backlight Driver:** An external PWM-controlled LED driver is typically needed to power the LCD backlight.