A TFT LCD Display module consists of a TFT LCD panel, one or more COG (chip-on-glass) or COB (chip-on-board) driver ICs, a backlight, and an interface. Several TFT display interface technologies exist today. Picking the right interface depends on specific end-product concerns. There are several types of TFT display interfaces which have been designed in the last number of years for various screen sizes, including LVDS, (Low-Voltage Differential Signaling) parallel, SPI (Serial Peripheral Interface) RGB and so on. Here is an overview of these display interfaces to give you a better idea of the variety of TFT LCD displays that are taking center stage.
TFT LCD Interfaces – The Technical
Typically, TFT interfaces are determined by the particular TFT panel size, its resolution.
SPI LCD Interface: Serial Peripheral Interface allows serial (one bit at a time) exchange of data between two devices. It has an advantage over parallel ones, that of simpler wiring. SPI also can have longer cables, since there is much less interaction or crosstalk in the cable. The downside of SPI is that you can’t read from the TFT LCD display, you can only write on it and it is slow. That’s why you normally see smaller TFT LCD screens use SPI.
MCU Parallel Interface: Many modern MCUs have built-in LCD controller function. There are two types that are commonly used, 6800 and 8080. Generally, MCU/Parallel interface consist of data signal(4/8/9/16 bits) and control signal. MCU interface is simple, but requires display RAM.
RGB Interface: RGB interface is a special kind of parallel interface. It requires no display RAM. MCU directly updates the TFT screen, sending Red Green & Blue sub-pixel data (16/18/24 bits) and timing signals. RGB interface provides high speed communication to TFT LCD, but it needs more data wires and controlling is more complex.
LVDS Interface: Low-voltage differential signaling is an electrical digital signaling standard. Devices with LVDS interface can communicate at very high speeds over inexpensive twisted-pair copper cables. It is much less susceptible to EMI and crosstalk issues, allowing the transmitting device to be located farther from TFT LCD display.
UART/RS232/RS485: These serial interfaces are used in Topway’s Smart TFT LCD display module. Universal Asynchronous Receiver/Transmitter (UART) is a block of circuitry responsible for implementing serial communication. Essentially, the UART acts as an intermediary between parallel and serial interfaces. On one end of UART is a bus of eight-or-so data lines (plus some control pins), on the other is the two serial wires – RX and TX.
HDMI Interface: High Definition Multimedia Interface is a connector and cable definition that supports high-quality and high-bandwidth streams of video and audio between devices.
MIPI DSI: MIPI Display Serial Interface defines a high-speed serial interface bewteen host processor and display module. The interface facilitates a high performance, low power and low EMI way to render brilliant color for the most dempanding image and video scenes.