LCD controller functions

LCD controller's function is to display drive signal, thereby driving the LCD. Users only need to write a series of registers, to complete the configuration and the display driver. In the process of designing LCD driver first and foremost is to configure the LCD controller and LCD controller in the configuration of the most important step is the frame buffer (FrameBuffer) designation. The user to display the contents are to be read out from the buffer to display on the screen. Frame buffer size is determined by the screen resolution and number of colors displayed decision. Drive frame buffer implementation is the focus of the entire drive the development process. S3C2410 the LCD controller can support two kinds of STN and TFT LCD. For STN LCD flat panel, the LCD controller can support four pairs of scan, 4-bit single scan, and 8-bit single scan three display types, support for 4 and 16 grayscale monochrome display mode, supports 256 colors and 4096 colors display, which can be accessed multiple resolution of the serial oled display, for example, 640 × 480,320 × 240 and 160 × 160, etc., in the 256-color display mode, maximum support 4096 × 1024,2048 × 2048 and 1024 × 4096 display. TFT LCD flat panel can support 1-2-4-8bpp (bits per pixel) color palette color palette display mode and non-16bpp true color display.
Frame buffer is seen in the Linux 2.2.xx and later kernels which a driver interface, this interface will display device abstraction for the frame buffer device area. The image frame buffer hardware device provides an abstraction process, which represents the number of video hardware, allows the application software through a well-defined interface to access the graphics hardware device. Such software without knowing any thing related to the underlying hardware drivers (such as hardware registers). It allows the upper application in graphics mode to read and write directly to the display buffer and the I / O control and other operations. Through special device nodes can access the device, such as / dev / fb *. Users can use it as an image display memory, be mapped into the process address space, you can read and write operations, and read and write operations can be reflected to the mini lcd module.
Frame buffer device corresponding device file is / dev / fb *. If the system has multiple graphics cards, Linux also supports multiple frame buffer device, up to 32, that is / dev/fb0 ~ / dev/fb31. The / dev / fb then point to the current frame buffer device, under normal circumstances, the default frame buffer device is / dev/fb0.
Frame buffer device also belongs to a character device, using the "file level - driver layer" interface mode.