With the development of technology, LCD screens have become popular among many users due to their advantages such as no battery radiation, large display capacity, and long service life. However, problems often arise when using LCD screens for extended periods. What are some common issues that LCD screens may encounter?

First: LCD image misalignment

      The LCD display experiences horizontal displacement, or displays a few pixel-wide colored, white, or black stripes at the top or bottom. Generally, this issue arises due to incorrect initialization parameter settings, related to the horizontal or vertical synchronization signals. If there is a displacement or misalignment in the display position, inspect the width, front-to-back delay, and polarity matching of the horizontal and vertical synchronization signals between the LCD module and the LCD controller on the CPU. The most probable cause is a mismatch in the front-to-back delay time of the retrace.

Second: Misalignment, overlapping, and duplication of large LCD images

      When a wide range of images appear misaligned, superimposed, or duplicated on the LCD display, this issue is generally not caused by delays in the horizontal sync or vertical sync signals, and these factors can be basically ruled out. You can check whether the parameters of functions such as sampling are normal. Another possible reason is that due to differences in the hardware platforms of the LCD screens, there may be discrepancies in timing or clock frequency. In such cases, the first step is to carefully calculate the DMA transmission parameters. For other situations, specific analysis should be conducted based on the specific problem.

 Third: There is a screen flicker when the LCD lights up at startup

      This issue typically arises when the backlight is already on before the LCD has fully prepared to refresh its first image after initialization. The solution is to increase the delay before turning on the backlight during UBOOT accordingly.

 Point 4: The LCD does not light up

      There are many reasons why an LCD might not light up, but when this issue arises, the first step should be to determine whether the LCD has properly completed initialization. The simplest method to do this is by measuring the voltage across the capacitor on the LCM's FPC.