A20-lime2 + 15.6'' FHD

[warhawk]

Hello. I conected the a20-lime2 with the 15.6'' fhd lcd and then setup the lcd correctly with the ./change_display_olimex_A20.sh script. The lcd now works ok but it is very very wavy like the refresh rate is very "false".

Any ideas?

[JohnS]

Bad wiring, I think.  Too long / needs grounds / impedance matching / etc.

What refresh rate & screen res did you pick & are they right for the display?

John

[warhawk]

Original olimex wires used (20cm). Also tried the display on olinuxino a20 with even worse waving and weird lines.

./changedisplay script setting for the specific lcd used. 1920x1080 at 60hz.

[JohnS]

That's a big bandwidth increase, right?  Follow rules for such things...

(Find an electronics engineer if you don't know them.)

John

[dave-at-axon]

Is this an RGB or LVDS connection?

For RGB the design of the connector on the A20 is poor. The LCD CLOCK is next to a SYNC line and it can cause this to jitter if the cable is too long. It should ideally be separated by a GND line either side.

Even with my short cable on a 7" LCD I get poor display if this is just a few mm too long.

I've designed an LVDS interface for the LCD but yet to build and test the board

[warhawk]

I am using the lvds interface. I just thought the lime2 would match "plug&play" with this lcd. Olimex ltd has a specific wire and specific model of screen that sells as accessories with the lime2 (and specific ./changedisplay script for the specific lcd). I expect them to work out of the box. Am I wrong? It's like buying and paying twice the price of the usb to ethernet adapter just because it is tested end certified for olinuxino and finally on use it would have problems. It's the same thing.

I would like an official answer from olimex ltd for this.

ps. Also the lcd has about 3-4 burnt pixels out of the box. But that is another conversation.