Brief Introduction to the Types of LCD Interface
LCD interface is an important connection between the controller and LCM, and the controller can transmit the required information to the LCD to display through the interface. This article will briefly introduce some interfaces that are commonly used: MCU, SPI, MIPI, and IIC.
MCU (Micro controller Unit) is one of the most commonly used interface, which is named because it is widely used in the field of microcontroller. One of the distinctive features of MCU is to transmit data in parallel. Compared with serial interfaces, parallel interfaces can transmit multiple data bits at the same moment, thus realizing the rapid transmission of display data, commands and other information to the control IC of the display. However, since parallel transmission requires more pins, as the transmission distance increases, the problems of signal synchronization and interference will gradually become apparent, which also limits its application in long-distance transmission scenarios. The transmission of MCU is simple and direct, and it’s design is concise and easy to understand and implement, so it is suitable for some simple displays, such as segment code LCD or low-resolution dot matrix display, as well as for some cost-sensitive display with less requirements.
SPI (Serial Peripheral Interface) is a conventional high-speed, full-duplex serial communication interface, only a few pins can realize data transmission, which makes it be highly favored in some space-limited equipment. It can adjust the clock frequency flexibly to optimize the transfer speed for different device requirements and data transfer volumes. However, there is usually only one host, and it does not support multiple hosts to communicate at the same time in the SPI system. SPI is commonly used in some small OLED displays or other low-power, small-size display.
MIPI (Mobile Industry Processor Interface) is a synchronous serial interface designed specifically for high performance applications such as mobile devices. Its features of low power consumption, high-speed transmission and a small number of pins make it perfect to meet the mobile devices with requirements of long lifespan, thinness and lightness, as well as high-resolution displays and high-quality image and video processing. It adopts advanced differential signaling technology, which can effectively reduce signal interference and noise while transmitting data at high speed. However, this kind of interface requires high technical level and professional knowledge in designing and realizing, which makes it relatively difficult to develop and the transmission distance is relatively short. MIPI is widely used in many fields such as smart phones, tablet PCs, digital cameras, automotive electronics, and so on.
IIC (Inter- Integrated Circuit), also known as I2C, is a two-wire serial bus structure that transmits information through a clock line and a data line. The most important feature is that multiple devices can be connected to a bus to realize the centralized control and management of multiple followers by the leader, which is convenient for building a small distributed system for communication between multiple devices. However, as IIC uses level signal to transmit, the transmission distance is limited by the level signal attenuation and noise interference. Therefore, the communication distance should generally not be too long, usually within a few meters. IIC is often used in the control of some auxiliary equipment, such as display brightness adjustment, contrast adjustment and other control circuits.
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