A Collection of Screen Interface Types (MCU, RGB, MIPI, LVDS, HDMI)

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1. Internal Interfaces (Onboard Interfaces for Embedded Systems)

1. Parallel Interfaces

(1) MCU Interface

The standard term for the MCU interface (Microcontroller Interface) is the 8080 bus standard proposed by Intel, so it is commonly referred to as the I8080 interface or 8080 interface. Its name originates from its early applications primarily in the microcontroller (MCU) field, such as embedded systems and mid-range mobile phones.
Two Modes of MCU Interface The MCU interface includes two timing modes:

8080 Mode (Intel Standard): Control signals are CS, RS, RD, WR, transmitting data through parallel data lines, and is the most widely used.
6800 Mode (Motorola Standard): Control signals are CS, RS, E (latch signal), with timing different from 8080, and is now rarely used.

Other Aliases

The 8080 interface has various other names, such as:

DBI (Data Bus Interface): Data bus interface;
MPU Interface: Microprocessor interface;
CPU Interface: Emphasizing direct connection to the processor.

Difference from RGB Interface

MCU Interface: Relies on the screen’s built-in GRAM (Graphics RAM), requiring commands to write data, suitable for small screens (e.g., 2.8~4.3 inches) and low refresh rate scenarios (e.g., static images), commonly using CS, RS, RD, WR signals. (e.g., screens from ZLG and Firefly development boards)
RGB Interface: Directly provides graphics memory from system memory (e.g., some SoC/MCU chips integrate DDR2/DDR3/PSRAM/nor FLASH). Transmits pixel data through synchronization signals (e.g., HSYNC, VSYNC), suitable for large screens and high refresh rate scenarios (e.g., video playback).

(2) RGB Interface (DPI Interface)

Definition: Directly transmits pixel RGB data, without GRAM, with graphics memory provided by system memory.
Characteristics:

Control signals: HSYNC (line sync), VSYNC (frame sync), DOTCLK (pixel clock).
Data width: 16/18/24 bits, supports high-speed refresh (suitable for video).

Applications: Medium-sized screens (2~10 inches), such as smart meters, in-car central control, tablets.

Comparison Item	RGB565	RGB666	RGB888
Bit Depth	16 bits (5 bits red, 6 bits green, 5 bits blue)	18 bits (6 bits each for red, green, blue)	24 bits (8 bits each for red, green, blue)
Color Count	65,536 colors	262,144 colors	16,777,216 colors
Color Accuracy and Performance	Fewer colors, complex color transitions and subtle color differences are prone to distortion	Higher color accuracy than RGB565, transitions are more natural, but still some color loss	Rich color performance, smooth transitions, can perfectly restore true colors
Data Storage and Transmission	2 bytes per pixel, small data volume, occupies fewer resources	2.25 bytes per pixel, moderate data volume	3 bytes per pixel, large data volume, high storage and transmission requirements
Application Scenarios	Embedded devices, low-resolution displays	Scenarios with certain color requirements, need to balance storage and processing costs	Computer monitors, HD TVs, digital cameras, professional image and video processing software, etc.

2. Serial Interfaces

(1) SPI Interface

Characteristics: 3/4 wire serial transmission, low speed, supports only small screens (≤2 inches).
Applications: Segment LCDs, small-sized OLEDs (e.g., wristband screens).

Three-wire SPI (SCK, SDIO, SS), four-wire (SCK, MISO, MOSI, SS).

(2) MIPI-DSI Interface

Definition: A high-speed serial interface standard in the mobile industry, transmitting differential signals.
Characteristics:

Fewer pins (e.g., D0P/D0N differential pair), strong anti-interference, supports high resolution (720P~2K).
Bidirectional communication, supports power-saving mode.

Applications: Mobile phones, tablets, small-sized laptops.

1. Note the distinction:

Upper Layer Protocol (Application Layer)

Physical Layer

Display

MIPI DSI

(Display Serial Interface)

MIPI D-PHY

Camera

MIPI CSI

(Camera Serial Interface)

MIPI C-PHY

2. What is a MIPI Lane, and what is the difference between 1 Lane MIPI and 4 Lane MIPI?

A lane can be understood as a data transmission channel. MIPI’s 1 lane, 2 lane, and 4 lane represent 1 data channel, 2 data channels, and 4 data channels respectively; the more channels, the stronger the data transmission capability, and each must also be paired with a differential clock.

Number of Lanes	Bandwidth	Number of Pins	Cost	Power Consumption	Applicable Scenarios	Number of Differential Pairs
1 Lane	Low	Few	Low	Low	Small, low-resolution screens	2 pairs
2 Lane	Medium	Moderate	Moderate	Moderate	Medium-sized, medium-resolution screens	3 pairs
4 Lane	High	Many	High	High	High-resolution, high-frame-rate screens	5 pairs

(3) LVDS Interface

Definition: Low Voltage Differential Signal interface, encodes RGB data into differential signals for transmission.
Characteristics:

Long transmission distance (over 10 meters), strong anti-interference, suitable for large screens.
Requires dedicated chips to convert TTL/RGB signals.

Applications: In-car screens, industrial displays, large-sized tablets.

2. External Interfaces (Universal Standard Interfaces for Device Interconnection)

1. VGA (D-Sub)

Definition: An analog signal interface that transmits RGB primary colors and line/frame sync signals.
Characteristics: Strong compatibility but prone to interference, gradually being replaced by digital interfaces.
Applications: Old computers, projectors.

2. DVI

Definition: A digital interface, divided into DVI-D (pure digital) and DVI-I (compatible with analog).
Characteristics: Supports HD (1080P), no signal conversion loss.
Applications: Computer monitors, graphics cards.

3. HDMI

Definition: High-Definition Multimedia Interface, transmits audio and video simultaneously.
Characteristics:

High bandwidth (HDMI 2.1 reaches 48Gbps), supports 4K/8K, HDR.
Supports HDCP copyright protection.

Applications: TVs, set-top boxes, game consoles.

4. EDP

Definition: Embedded DisplayPort, high-speed serial interface.
Characteristics: Fewer pins, high bandwidth, supports 2K/4K large screens.
Applications: Laptops, monitors, all-in-ones.

Supplement:EDP interface is different from EPD (commonly refers to Electronic Paper Display, Electronic Paper Display) which are two completely different concepts.

3. Interface Comparison and Selection Recommendations

Interface Type	Transmission Method	Graphics Memory Location	Typical Size	Scenarios
MCU/8080	Parallel	Built-in GRAM	2~4.3 inches	Microcontrollers, low-end devices
RGB	Parallel	System Memory	2~10 inches	Smart hardware, in-car central control
MIPI-DSI	Serial Differential	System Memory	3~10 inches	Mobile phones, tablets
LVDS	Serial Differential	System Memory	Over 7 inches	In-car, industrial displays
HDMI/DVI	External Standard	Host Memory	Over 10 inches	TVs, external computer monitors

Conclusion

Small Screens (≤4.3 inches): Prefer MCU/8080 Interface (e.g., screens driven by STM32).
Medium Screens (2~10 inches): RGB Interface is cost-effective, for high speed choose MIPI-DSI. (e.g., ITE, Sigmastar, etc.)
Large Screens (>7 inches): LVDS or EDP, for long-distance transmission prefer LVDS.
External Connections: HDMI is mainstream, use VGA for older devices.

Disclaimer

Note: This article only represents the author’s views, readers should verify its authenticity and legality. If you find any errors in the content or it infringes your rights, please contact (WeChat haizililiang), and this public account will promptly modify or delete it.

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