Comprehensive Guide to LCD Monitor Pin Interfaces

LCD (Liquid Crystal Display): also known as liquid crystal display. Widely used in embedded, mobile, and PC applications.

This article mainly introduces common LCD classifications.

LCD classifications are as follows

Divided into several categories based on signal type: TTL/LVDS/EDP/MIPI
Classified by material (for TFT-LCD): TFT-TN/TFT-IPS/TFT-VA.
Interface types include: RGB mode, SPI mode, MDDI mode, VSYNC mode, DSI mode, MCU mode, etc.

Scan the QR code to join the embedded group

▼

Comprehensive Guide to LCD Monitor Pin Interfaces

Common LCD interface modes introduction

RGB mode

RGB mode refers to the RGB screen we commonly talk about, which transmits data via RGB (TTL signal) parallel data lines, widely used in TFT-LCDs of 5 inches and above. Serial/Parallel: Serial; Pins: RGB data + clock + control pins; Data formats include: RGB565, RGB666, RGB888.

SPI mode

Standard SPI interface. It is divided into two categories: SPI control signals + RGB data lines and SPI control/DATA. Specifics depend on the manufacturer’s manual. The former SPI only transmits control signals, while the latter transmits both control and data.

Due to transmission speed limitations, if data is transmitted directly through SPI, it can be seen that the screen cannot be made particularly large.

MDDI mode

An interface launched by Qualcomm in 2004. Pins include host_data/strobe, client_data/strobe, etc. Generally, it is not widely used in embedded systems.

MIPI-DSI mode

MIPI-DSI mode, commonly referred to as MIPI screen. Differential signal. Suitable for high-speed applications.

MCU mode

MCU mode refers to what we commonly call MCU screens, with the standard name I80 (I8080), named due to its widespread use in microcontroller fields. There is also M6800 (Motorola 6800).

Advantages: Simple control, no clock synchronization required. Disadvantages: Limited by internal GRAM, making it difficult to achieve large screens (over 3.8 inches). Display rate is slow, requiring control commands to refresh the display.

80808080, also known as the Intel bus, is a commonly used bus in MCU mode, consisting of data and control buses. Control pins are as follows:

Timing diagram:

6800

M6800, also known as Motorola bus, has the same design philosophy as I8080. The main difference is that in this mode, the read/write control bit is on a WR pin, and an additional latch signal (E) is added. Control pins are as follows:

Timing diagram:

VSYNC mode

This mode adds a VSYNC signal based on the MCU mode, used for animation updates. In this mode, internal display operations are synchronized with external VSYNC, allowing for higher-speed animation display than internal operations. However, this mode has speed limitations, meaning that the internal SRAM write speed must be greater than the read speed of SRAM.

Summary

The following diagram is extracted from a datasheet, basically containing common interface screens in embedded systems. In fact, for developers, what we are often more concerned about is the external interface.

RGB: (DPI) RGB565/RGB666/RGB888

MCU:I8080/M6800 (8/9/16/18/24bit)

SPI: 3line/4line

MIPI-DSI: Data_N/P, Clock_P/N

Limited by interface pins, speed, and cost, we will choose the appropriate screen, only needing to care about what kind of interface and protocol, and then write the driver accordingly.

Scan the QR code to join the embedded group

▼

Related posts

Leave a Comment Cancel reply