The LCD display has a variety of interfaces and the classification is very thin. Mainly look at the LCD drive mode and control method, currently there are several types of color LCD connection on the phone: MCU mode (also written in MPU mode), RGB mode, SPI mode, VSYNC mode, MDDI mode, DSI mode. There are TFT modules that have RGB interfaces.
More applications are MCU mode and RGB mode.
MCU interface: The command will be decoded, and the timing generator will generate timing signals to drive the COM and SEG drivers. Since the data can be stored in the internal GRAM of the IC and then written to the screen, the LCD of this mode can be directly connected to the MEMORY bus. Display data is written to DDRAM and is often used for still picture display.
RGB interface: When writing LCD register setting, there is no difference between the MCU interface and the MCU interface. The only difference is the way the image is written. There is no internal RAM, so HSYNC, VSYNC, ENABLE, CS, RESET, and RS cannot be directly connected to the GPIO port of MEMORY. The GPIO port is required to simulate the waveform. Display data is not written to DDRAM, direct write screen, fast, often used for displaying video or animation.
The MCU mode is named because it is mainly used in the field of microcontrollers. After the heavy use of low-end mobile phones, its main features are cheap. The standard terminology of the MCU-LCD interface is Intel's 8080 bus standard, so I80 is used to refer to the MCU-LCD screen in many documents. Mainly can be divided into 8080 mode and 6800 mode, the main difference between the two is timing. Data bit transmission has 8 bits, 9 bits, 16 bits, 18 bits, and 24 bits. The connection is divided into: CS/, RS (register selection), RD/, WR/, and then the data line. The advantage is that the control is simple and convenient, and no clock and synchronization signals are needed. The disadvantage is that it costs GRAM, so it is difficult to achieve a large screen (3.8 or above). For the LCM of the MPU interface, the internal chip is called the LCD driver. The main function is to transform the data/command sent by the host into RGB data of each pixel and display it on the screen. This process does not require point, line, or frame clocks. The Driver IC of the LCD of the MCU interface is equipped with GRAM. The Driver IC acts as a coprocessor of the MCU and accepts the Command/Data sent by the MCU, which can work relatively independently. For the LCM (LCD Module) of the MCU interface, the internal chip is called the LCD driver. The main function is to transform the data/command sent by the host into RGB data of each pixel and display it on the screen. This process does not require point, line, or frame clocks.
The VSYNC mode is actually adding a VSYNC signal to the MCU mode for motion picture update, which is very different from the above two interfaces. This mode supports direct animation display, which provides a minimal change to the MCU interface and an animation display solution. In this mode, the internal display operation is synchronized with the external VSYNC signal. Animated display at a higher rate than internal operations can be achieved. However, due to the different modes of operation, this mode has a limitation on the rate, that is, the write rate to the internal SRAM must be greater than the rate at which the internal SRAM is read.
RGB mode is a large screen with more modes, data bit transmission also has 6 bits, 16 bits and 18 bits, 24 bits. Connections generally include: VSYNC, HSYNC, DOTCLK, CS, RESET, and some also require RS, and the rest is the data line. Its advantages and disadvantages are exactly the opposite of the MCU mode.
The SPI mode is used less, there are 3 lines and 4 lines, the connection is CS/, SLK, SDI, SDO four lines, the connection is small but the software control is more complicated.
MDDI mode, the interface MDDI proposed by Qualcomm in 2004, can improve the reliability of mobile phones and reduce power consumption by reducing the connection, which will replace the SPI mode and become a high-speed serial interface in the mobile field. The connection is mainly a few lines of host_data, host_strobe, client_data, client_strobe, power, and GND.
DSI mode serial bidirectional high-speed command transmission mode, the connection has D0P, D0N, D1P, D1N, CLKP, CLKN.