Olimex Support Forum

OLinuXino Android / Linux boards and System On Modules => A20 => Topic started by: mcffeyel on November 11, 2013, 01:53:45 PM

Title: A20 + LCD screen flickering
Post by: mcffeyel on November 11, 2013, 01:53:45 PM
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 !
Title: Re: A20 + LCD screen flickering
Post by: Linux4sbc on November 11, 2013, 10:08:43 PM
Hi,

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

I send LCD back to Olimex for replace.
Title: Re: A20 + LCD screen flickering
Post by: tlhingan on November 13, 2013, 01:03:10 AM
Try turning the brightness down.
That fixed mine.
Title: Re: A20 + LCD screen flickering
Post by: bubi on November 14, 2013, 01:53:50 AM
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
Title: Re: A20 + LCD screen flickering
Post by: bubi on November 19, 2013, 08:51:42 PM
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?
Title: Re: A20 + LCD screen flickering
Post by: ivolkov on February 05, 2014, 07:34:37 PM
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.

(http://i57.tinypic.com/2rx9le9.jpg)

(http://i58.tinypic.com/30i9lzk.jpg)
Title: Re: A20 + LCD screen flickering
Post by: bubi on February 06, 2014, 01:20:59 PM
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