学习DSP外设之LCDC的配置和应用

最新推荐文章于 2024-04-07 15:42:32 发布

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这篇博客详细介绍了LCDC的两个控制器——同步Raster Controller和异步LIDD Controller，包括它们的功能和工作原理。同时，讲解了Pixel Clock、Horizontal Clock、Vertical Clock的计算和作用。此外，还讨论了在使用Raster Controller和LIDD Controller时，DMA的工作方式，并强调了正确配置LIDD_CTRL或RASTER_CTRL寄存器以及所有定时寄存器的重要性，以启用DMA传输。

看了这个外设的说明，发现没有initialion。。。那就从头介绍吧

一、介绍说明

LCDC有两个独立的控制器，同步Raster Controller 和异步LCD InterfaceDisplay Driver (LIDD) controller。

同步Raster Controller：It supports a wide variety of monochrome and full-color displaytypes and sizes by use of programmable timing controls, a built-in palette, and a gray-scale/serializer.Graphics data is processed and stored in frame

异步LIDD controller：The LIDD Controller supports the asynchronous LCD interface. It provides full-timing programmabilityof control signals and output data.

二、clock

1.Pixel Clock 计算如下：where CLKDIV is a field in the LCD_CTRL register and should not be 0 or 1.

Passive (STN：STN的每个点只有点亮和熄灭两种状态，可以通过“抖动算法”来实现灰度或彩色显示。STN属于无源Passive型LCD，一般最高能显示65536种色彩) mode.LCD_PCLK only transitions when valid data is available for output. It does nottransition when the horizontal clock is asserted or during wait state insertion.
Active (TFT：液晶为每个像素都设有一个半导体开关，其加工工艺类似于大规模集成电路) mode.LCD_PCLK continuously toggles as long as the Raster Controller is enabled.

2.Horizontal Clock (LCD_HSYNC) ：每行结束clock

3.Vertical Clock (LCD_VSYNC) ：all lines in a frame have been transmitted to the LCD 帧结束clock

三、DMA

When the Raster Controller is used, the DMA engine reads data from a frame buffer and writes it to theinput FIFO (如上第一幅图所示). The Raster Controller requests data from the FIFO for framerefresh; as a result, the DMA’s job is to ensure that the FIFO is always kept full.

When the LIDD Controller is used, the DMA engine accesses the LIDD Controller's address and/or dataregisters.

In addition, the LIDD_CTRL register (for LIDD Controller) or the RASTER_CTRL register (for RasterController) should also be configured appropriately, along with all the timing registers.

To enable DMA transfers, the LIDD_DMA_EN bit (in the LIDD_CTRL register) or the LCDEN bit (in theRASTER_CTRL register) should be written with 1.