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morris
f24c115f4b
Also adopt the FourCC standard to describe color format. See also https://developer.espressif.com/blog/2025/04/esp-fourcc-introduction/
63 lines
2.7 KiB
Markdown
63 lines
2.7 KiB
Markdown
# ESP Hardware Abstraction Layer for LCD Peripherals
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> [!NOTE]
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> This component is currently in beta. Its API, behavior, and compatibility may change at any time and without notice; backward compatibility is not guaranteed. Use caution when integrating into production systems.
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## Overview
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The `esp_hal_lcd` component provides a **Hardware Abstraction Layer** for LCD (Liquid Crystal Display) controllers and MIPI DSI (Display Serial Interface) peripherals across ESP-IDF supported targets. This HAL enables efficient communication with various display interfaces including I80 parallel, RGB parallel, and MIPI DSI serial interfaces.
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## Architecture
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The LCD HAL is structured in two main sub-layers:
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1. **HAL Layer (Upper)**: Defines the operational steps and data structures required to control LCD peripherals (e.g., initialization, clock configuration, data transmission).
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2. **Low-Level Layer (Bottom)**: Serves as a translation layer between the HAL and the register files defined in the `soc` component, handling target-specific register configurations.
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## Supported LCD Interfaces
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This HAL supports various LCD interface types depending on the ESP chip:
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- **I80 (Intel 8080) Parallel Interface**: 8-bit/16-bit parallel interface commonly used for MCU-based displays
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- **RGB Parallel Interface**: Direct RGB pixel data interface for high-performance displays
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- **MIPI DSI Interface**: High-speed serial interface supporting:
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- DSI Host Controller
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- DSI Bridge Controller
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- PHY layer configuration
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- DCS (Display Command Set) commands
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- Generic read/write operations
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## Features
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### LCD Common Features
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- Pixel clock (PCLK) calculation and configuration
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- Multiple color format support using FourCC standard:
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- RGB565, RGB888
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- YUV422 (YUYV, YVYU, VYUY, UYVY)
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- GRAY8 (8-bit grayscale)
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- RGB data endian configuration (MSB/LSB first)
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- Color space conversion (RGB ↔ YUV)
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- YUV conversion standards (BT.601, BT.709)
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- Color range control (Limited/Full)
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### MIPI DSI Specific Features
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- PHY PLL configuration for high-speed lanes
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- Virtual channel management
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- DCS command transmission (short/long writes)
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- Generic interface for command/data operations
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- Test pattern generation (vertical/horizontal bars, BER patterns)
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- Multi-lane data transmission support
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- DPI (Display Pixel Interface) clock configuration
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## Usage
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The HAL functions primarily serve ESP-IDF LCD peripheral drivers such as `esp_lcd` component.
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Advanced developers can use these interfaces directly when implementing custom display drivers, with the understanding that API stability is not guaranteed.
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## Dependencies
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- `soc`: Provides chip-specific register definitions and peripheral capabilities
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- `hal`: Core hardware abstraction utilities, macros, and color type definitions
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