The Most Common Interfaces Seen on TFT Displays
A TFT, or Thin-Film Transistor, utilizes a display that allows for each pixel to be controlled by a transistor and separately address each position. The components of a TFT LCD module are a TFT LCD panel, one or more COG or COB driver ICs, a backlight, and an interface. An interface is a shared boundary across which two separate components of a computer system exchange information. As TFT displays have started being mass produced, production has improved, and the price has become more affordable.
There are now a number of TFT display interface technologies. The best interface to choose relies on particular end-product considerations. The last several years have seen the development of numerous TFT display interfaces, including LVDS (Low-Voltage Differential Signaling), parallel, SPI (Serial Peripheral Interface), and I2C or I2C (also known as I squared C) display, and others.
An SPI or Serial Peripheral Interface enables data exchange between two devices. Compared to parallel ones, it has the benefit of more intuitive and simple wiring. Since there is substantially less contact or crosstalk in the cable, SPI also allows for longer cables. The disadvantage of SPI is that it is slow and only allows for writing to the TFT LCD panel. SPI is typically used in smaller TFT LCD screens because of this. But perhaps your project might require a built-in LCD controller, for which an MCU Parallel interface might be a good fit.
An MCUPI or an MCU Parallel interface is usually pretty simple and usually requires display RAM. There are two common types that are found; the first is 6800, and the other is 8080. 8080 is nRD and nWR, 6800 is RD/nWR and E. A unique sort of parallel interface is the RGB interface. There is no need for display RAM. The MCU directly updates the TFT screen by delivering Red, Green, and Blue sub-pixel data (16/18/24 bits) and timing signals. The RGB interface offers a high-speed connection but requires more data cables and has more complicated controls.
A high-speed serial interface between a host CPU and a display module called MIPI Display Serial Interface allows for the integration of displays to provide high performance, low power, and low electromagnetic interference (EMI) while also lowering the number of pins and retaining vendor compatibility. Designers can use MIPI DSI to provide transmission of stereoscopic content and to enable excellent color rendering for the most demanding picture and video situations.
Low-voltage differential signaling, or LVDS, is a high-speed, long-distance digital interface that transmits serial data (one bit at a time) through two copper wires that are 180 degrees apart from one another. This setup makes the noise easier to identify and filter, which lowers noise emissions. Focus LCDs offers a versatile display that uses this technology, E70RA-HW520-C. The monitor in question is a 7.0″ TFT with 1024×600 pixels and a maximum color depth of 16.7M. The inbuilt gate and source driver ICs in this display can be programmed using a typical graphics controller.
HDMI is one that many consumers may already be familiar with. High Definition Media Interface provides a connector and cable definition that supports high-bandwidth video and audio streams. HDMI is an almost direct replacement for analog video standards.
There are then a diverse set of interfaces that can be considered for your display project; whether you decide to go with HDMI, LVDS, MIPI DSI, or the others mentioned, or simply can’t decide, feel free to contact Focus LCDs, where we can address use-case specific questions and provide additional details.