A20 + LCD screen flickering

Started by mcffeyel, November 11, 2013, 01:53:45 pm

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mcffeyel

Hi,

I have an A20 with the LCD-7-TS from Olimex connected to it.

The LCD is flickering a bit when only the desktop is shown. When a terminal window (for instance, but it's the same with other apps) is open, the whole screen is dramatically flickering, making it totally unreadable.

Does someone have a fix for this problem ?

I'm using linux (debian) on it. The system is powered by a 12V 2.5A power supply. To connect the display to the board I'm using a standard 40 pins ribbon cable.

Thanks !

Linux4sbc

Hi,

I have same problem.
Think, that is hardware problem in LCD or voltage converter.

I send LCD back to Olimex for replace.

tlhingan

Try turning the brightness down.
That fixed mine.

bubi

Hi,

I have the same problem too, but only in desktop environment and only from the last release.
It can be due to a setting in script.fex or in a configuration file of XFCE? (or maybe are the mali drivers?)

Thanks
Renato

bubi

I tried to install android on the nand and I don't have any problems with LCD (so it works properly).

I discover that if I move mouse pointer along the edges of the LCD it stops flickering (in xfce).

I unistalled both xfce4 and lightdm, so i can work only in shell, and the LCD continue flickering in some pseudo-graphical intefaces (like the one in sysv-rc-conf), but no in others (like one in dpkg-reconfigure locales).

I tried to change some parameters in the fex file but nothing changes.

Does anyone have a solution?

ivolkov

February 05, 2014, 07:34:37 pm #5 Last Edit: February 05, 2014, 07:37:32 pm by ivolkov
I had exactly the same problem with A13-WIFI. I noticed that flickering changes when I bend LCD cable or even when I put my hand next to it. I suggested that something wrong with cable and shortened it to about 2.5 inches. And guess what, flickering stops and display works perfect now.

Weird, isn't it? In android display work fine. Seems to me that some settings in linux image is "almost wrong" or "at the edge of failure", so the length and quality of cable starts to be important.

In case someone want to try this solution, keep in mind that it's difficult to disassemble the cable without breaking it. I managed to broke clamps that keep connector in place, but it works fine anyway after reassembling. Just had to be a little more carefully with it now.




bubi

Hi ivolkov,
Good idea, i'll try it!
Infact I noted that if I touch the board of the LCD near the connector, the LCD stops flickering.
Nevertheless I resolved modifying the script.bin in according with this solution: https://www.olimex.com/forum/index.php?topic=1942.msg10886#msg10886