Sometimes LCD display is initialized half white.

[rodolfodias]

Rarely right after the startup my LCD display shows half the screen completely white, the other half shows the software without problems. The main problem here is that to see this problem I have to initialize my hardware a lot of times, I don't have the exactly figures but maybe once every one hundred initializations. Once the display is initialized with the problem the software and the touchscreen work as expected. But I see a pattern that maybe can help me to understand what goes on when the problem happens.

• The screen is always divided in half vertically with one half working and other in white. If this is a random bug, the screen would be white on diferent proportions horizontally or vertically;
• The half section that does not show the software is always white. After a couple of tests I've noticed that the white color is the color when nothing is written on the pixel;
• The bug is very rare. And even at this low probability, when this happens the problem is the same, half the screen on white color;
  
  

I am using a LPC1788 connected to a LVDS transmitter (DS90C383B) and then to my LCD (HDA700L-GHL - 7”, WVGA 800 X480 , TFT Color Graphics ,White LED Backlight).

Can someone give me some advice? Thanks.

[soledad]

Hello,

Unfortunately we don’t have test and reproduce this issue, however, for your description, this issue I may related the synchronization so you can check the below points:

1. According with the DS90C383B documentation, Asserting the PWR DOWN pin will effectively place the device in reset and disable the PLL, enabling the LVDS Transmitter into a power saving standby mode. However, it is still generally a good practice to assert the PWR DOWN pin or reset the LVDS transmitter whenever the clock/data is stopped and reapplied but it is not mandatory for the DS90C383B.
2. HSYNC, VSYNC, there are some back and front porch that required an LCD this values usually are defined in the LCD datasheet, you may be taking care of this values.

Have a great day,
Sol

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