4.3 inch LCD screen driver

1nnocent

4.3 inch LCD screen driver [Copy link]

When using a 4.3-inch LCD screen, the LCD drive frequency must be reduced due to project requirements. After the frequency is reduced, the frame rate will be reduced. The project has no requirements for the frame rate. When the frame rate is reduced to below 15MHz, the screen cannot display the image normally, and the phenomenon is a solid color backlight. There seems to be no relevant description in the relevant driver IC manual. Is this normal?

11493c6f8318465ec9cc3b3bcb8fc3ba

The following is the information of the LCD used:

http://www.openedv.com/docs/modules/lcd/4.3-TFT%20LCD-800480.html

littleshrimp

There is information here. Looking at the timing in the manual, there are no requirements except ID and FM. Can you tell me which frequency it is?
Information link: https://pan.baidu.com/s/1zjNs9DQ2JfMsk0ONYhfZhA
Extraction code: 2su6

littleshrimp

In addition, the chip manual is also in that network disk.

peiqiu

According to the speed of the refresh rate, each time the display data is refreshed, it needs to read the data from the memory and output it to the LCD display. In this case, the frame rate and the refresh rate should be the same, that is, as long as the content in the memory range pointed to by the LCD controller is changed, it can be output at the speed of the refresh rate (frame rate). Of course, this memory relationship is very close. If the memory speed (bus frequency) cannot keep up, and the refresh rate configured by the LCD is too fast, that is, the memory bandwidth is insufficient, resulting in display flicker or jitter.

秦天qintian0303

peiqiu posted on 2022-9-14 16:05 According to the refresh rate, each time the display data is refreshed, it needs to read the data from the memory and output it to the LCD display. In this case, the frame rate and refresh...

This phenomenon only occurs when the speed is slow. There must be something wrong with the program.

吾妻思萌

There seems to be a post discussing this in the forum. You can search it. I think the refresh is based on the official defined rate. I think there must be a mismatch between the internal timing and the defined rate.

1nnocent

littleshrimp posted on 2022-9-14 15:20 There is information here. Looking at the timing in the manual, there are no requirements except ID and FM. Can you tell me which frequency it is? Information link: https:/ ...

It is the pixel clock. Line field blanking and effective pixels are based on this pixel clock.

1nnocent

Qintianqintian0303 posted on 2022-9-14 21:44 This phenomenon only occurs when the speed is slow, there should be a problem with the program

The program was modified using a routine, so the pixel clock was changed. The routine was 25MHz, and then it was changed to 20MHZ or 15MHz. If it is less than 15MHZ, the problem in the video will appear.

littleshrimp

1nnocent posted on 2022-9-16 19:25 The program was modified using the routine, so the pixel clock was changed. The routine was 25MHz, and then it was changed to 20MHZ or 15MHz. If it is less than 15MHZ, the video will appear...

The information in the link on the first floor says that the screen is an I8080 interface. From your description, it sounds like an RGB interface. If it is the latter, there should be a limit on the clock frequency. For example, the minimum DCLK of my screen cannot be lower than 19.75MHz

1nnocent

littleshrimp posted on 2022-9-16 20:59 The information in the link on the first floor says that the screen is an I8080 interface. From your description, it seems to be an RGB interface. If it is the latter, there should be a limit on the clock frequency, such as mine...

Yes, it uses the RGB interface

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