Recently, I applied for a GD32 development board at the EEWorld Forum, and tested the use of RGB-LCD in the past two days.
1RGB-LCD
RGB-LCD is an LCD screen with RGB interface, which corresponds to MCU-LCD. The difference between the two LCDs is:
-
MCU-LCD : It was originally designed for single-chip microcomputer (MCU). Because the memory of the single-chip microcomputer is small, the video memory is built in the LCD module, and the video memory is updated through special display commands. The MCU screen cannot be made large. The MCU screen displays the image, showing that the command to draw a dot needs to be sent to modify the MCU internal RAM.
- RGB-LCD : The video memory is used by the system memory. As long as the system memory is large enough, RGB-LCD can be made in a larger size. The RGB screen displays images, only the data is organized in the video memory. After the display is started, the LCD-DMA will automatically send the video memory to the display through the RGB interface, so the refresh rate of the RGB screen is faster.
The schematic diagram of the working mode of the two screens is as follows:
2 Image layer overlay
GD32F4 MCU provides a LCD interface called TLI (Tft-Lcd Interface) , which supports two independent display layers (plus the bottom background layer is 3 layers), and supports layer mixing and transparency adjustment . The cascading display process is shown in the following figure:
In this figure, layer 0 and layer 1 are two independent display layers, and there is also a BG layer, which is the background layer.
-
The BG layer can be specified to display a certain color, and this layer is at the bottom.
-
Layer 0 is superimposed on the BG layer. By adjusting the transparency of layer 0, it can be displayed in fusion with the BG layer.
- Layer 1 is superimposed on the top, and the transparency can also be adjusted. These three layers are superimposed together, which is the effect displayed on the screen.
Similarly, STM32F4 microcontroller provides a control interface called TLDC (Lcd-Tft Display Controller), which can also implement similar functions.
3 effect test
The demonstration video and the detailed introduction of this article have been published on the EEWorld forum for the first time. You can click "Read the original text" at the bottom left corner of the article to jump to view~