Detailed Explanation of LCD Interface Types: The "Language" Behind the Screen
When we look at the vibrant images on our phones, tablets, or dashboards, few people realize the high-speed "dialogue" taking place between the screen and the main control chip. This dialogue is conducted through different "languages"—the LCD interface.
The type of interface affects the screen's refresh rate and resolution, as well as the hardware's complexity and cost.
This article will give you a quick overview of the different types of LCD interface, what they are used for, and how to choose the right one for your project.
Contents
- I. Parallel Interface
- II. RGB Interface
- III. SPI Interface
- IV. MIPI DSI Interface
- V. LVDS Interface
- VI. eDP Interface
- VII. How to Choose the Right LCD Interface?
I. Parallel Interface
This is one of the most traditional and earliest LCD communication methods, commonly used in low-resolution displays such as character displays and small-sized dot-matrix displays.
Main Types:
8080 Interface: Proposed by Intel, commonly found in TFT screens. Data is read and written via independent control lines (such as RD, WR, CS).
6800 Interface: Motorola standard, similar to the 8080, but with slightly different control signal logic.
Advantages:
Simple control, low development threshold
Suitable for low-speed, low-cost applications
Disadvantages:
Many pins (usually 20 or more), complex PCB routing
Low data rate, unsuitable for high-resolution screens
Common applications:
Industrial control panels, small home appliance displays, low-end instrument panels
II. RGB Interface (Parallel RGB)
The RGB interface is a real-time transmission method. The main control chip continuously outputs the color data of each pixel to the screen in RGB signal form.
Features:
No frame buffer required, real-time refresh
Numerous signal lines (typically 18-24 data lines + synchronization signal)
High requirements for signal timing
Advantages:
Low latency, strong real-time display capability
Stable and smooth display
Disadvantages:
Complex interface, high pin usage
Strong electromagnetic interference (EMI), high requirements for wiring
Applications:
Instruments for cars, control systems for industry, and display systems that are built into products (like STM32 + RGB LCD solutions).
III. SPI Interface (Serial Peripheral Interface)
The SPI interface is a serial communication method, very common in small-sized LCDs, such as 1.44-inch or 2.8-inch TFT screens.
Features:
Uses 4 main signal lines (SCLK, MOSI, MISO, CS)
Transmission rate is typically in the tens of MHz range
Some screens use a "command + data" communication method
Advantages:
Fewer pins, simpler wiring
Low hardware cost
Easy to be compatible with various microcontrollers
Disadvantages:
Limited bandwidth, not suitable for high-resolution displays
Relatively weak real-time performance
Applications:
Smart bracelets, small meters, IoT terminals, toy displays
IV. MIPI DSI Interface (Mobile Industry Processor Interface – Display Serial Interface)
MIPI DSI is the most common interface used in modern smartphones and tablets. It was designed for high-speed displays with a high resolution.
Features:
Uses differential signaling (similar to LVDS), data transmission rate can reach several Gbps.
Few communication lines (typically 2-4 differential pairs).
Supports multiple display modes (Command Mode, Video Mode).
Advantages:
High speed, low power consumption.
Suitable for high resolution (e.g., 1080p and above).
Strong anti-interference capability.
Disadvantages:
Complex protocol, difficult driver development.
High hardware debugging threshold.
Applications:
Smartphones, tablets, VR headsets, high-end automotive central control screens.
V. LVDS Interface (Low Voltage Differential Signaling)
The LVDS interface is often used in laptops, industrial displays, and automotive display systems. It is a high-speed differential signaling interface.
Features:
Supports high-bandwidth data transmission
Uses low-voltage differential signals (low power consumption, low interference)
Typically used for large-size, high-resolution screens
Advantages:
Stable and reliable, strong anti-interference
Can transmit signals over long distances
Performance close to MIPI DSI
Disadvantages:
Higher cost
Many interface specifications, requiring matching driver boards
Applications:
Laptop displays, automotive central control screens, industrial touch display systems
VI. eDP Interface (Embedded DisplayPort)
eDP is an embedded version of DisplayPort. It is slowly replacing LVDS as the standard interface for laptops and all-in-one PCs.
Features:
Extremely high transmission rate (up to 8.1Gbps/lane)
Supports 4K and even 8K resolutions
Strong compatibility with DisplayPort
Advantages:
Large bandwidth, low power consumption
Adaptive refresh rate (energy saving)
Lighter cables, less interference
Disadvantages:
Higher cost, mainly used in high-end devices
Applications:
Laptops, high-end monitors, VR/AR devices
VII. How to Choose the Right LCD Interface?
| Application scenarios |
Recommendation API |
Features |
| Small size, low resolution (such as smart bracelets) |
SPI |
Simple and low cost |
| Medium-sized, real-time display (such as in-vehicle instrument clusters) |
RGB |
High real-time performance |
| High speed and high resolution (such as mobile phones and tablets) |
MIPI DSI |
High speed and low power consumption |
| Industrial/Laptop Large Screen |
LVDS / eDP |
Stable, high-resolution support |
Summary
The evolution of LCD interfaces is essentially a process from parallel to serial, from low speed to high speed, and from high pin count to high integration.
Different interfaces represent different stages of display technology development and determine the performance ceiling of devices.
When selecting a chip, engineers need to consider the following:
The types of interfaces supported by the main control chip
Screen resolution and refresh rate requirements
Cost and wiring complexity
EMI immunity requirements
Understanding these interfaces is like learning different "languages," enabling your screen and main control chip to communicate seamlessly.
