LCD interface mode

LCD interface mode

There are many LCD hardware interface modes, mainly including MCU mode, RGB mode, SPI mode, VSYNC mode, MDDI mode, etc.

1. MCU mode: One of the most commonly used connection modes at present, including 8080 mode and 6800 mode. Generally, the LCD DRIVER in this mode has a GRAM, and the data can be stored in the internal GRAM of the IC before writing to the screen. The connections are generally: #CS, RS (register selection), #RD, #WR, and then the data line. The advantage is: the control is simple and convenient, without clock and synchronization signal. The disadvantage is that it consumes GRAM. LCD 8080 mode and 6800 mode 8080/6800 are two level interface protocols for parallel data transmission. Specifically: 8080 uses two control lines of "read enable (RE)" and "write enable (WE)" respectively For read and write operations, the 6800 uses a combination of two control lines "total enable (E)" and "read and write selection (W/R)" for read and write operations

2. RGB mode LCD adopts one of more modes. Connections generally include: VSYNC, HSYNC, DOTCLK, ENABLE, RGB data lines, etc. Its advantages and disadvantages are just the opposite of MCU mode. The RGB connection method requires three clock lines, DOTCLK, HSYNC and VSYNC to ensure that RGB data is transmitted from the CPU to the LCD in the correct timing. DOTCLK is the system clock and provides a stable square wave clock, HSYNC is the line synchronization signal, and VSYNC is the field synchronization signal. . In addition, most of the current LCMs have a controller, which requires SPI to send control commands, and the initialization (setting window) commands are transmitted to the LCD controller through the SPI interface. Because the display data in RGB mode does not need to be written into GRAM, it can be written directly to the screen, and the speed is often used to display videos and animations.

3. SPI mode: Use less, the connection is CS/, SLK, SDI, SDO four lines, the connection is few but the software control is more complicated.

4. VSYNC mode: In this mode, a VSYNC (frame synchronization) signal line is added in MCU mode, and it is used for moving picture updates.

5. MDDI mode: The MDDI (Mobile Display Digital Interface) interface proposed by Qualcomm in 2004 can improve the reliability of mobile phones and reduce power consumption by reducing connections. This will replace the SPI mode and become a high-speed serial in the mobile field. interface.