Olimex Support Forum

OLinuXino Android / Linux boards and System On Modules => A20 => Topic started by: herter on January 26, 2014, 11:06:34 PM

Title: LVDS signals
Post by: herter on January 26, 2014, 11:06:34 PM
Hello,

I just got my A20-OLinuXino-MICRO-4GB, I tried her last week on HDMI and it works fine.
Now, I wonder whether this board can support the LVDS, and where can I get the LVDS signals (LCD connector)?

Thank you for your help!
best regards.
Title: Re: LVDS signals
Post by: gvi70000 on January 26, 2014, 11:12:22 PM
yes, the lcd connection is designed to be used with Olimex LCD's
Title: Re: LVDS signals
Post by: ph.fouquet on January 27, 2014, 10:03:24 AM
The A20 have LVDS output. The signal are MUX with TTL on LDC_CON (see the schematic on : https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/A10-OLinuXino-MICRO/A10-A20-OLINUXINO-MICRO-4GB_Rev_D.sch )

For switch TTL output to LVSD and configure the LCD properties (size timming...) use the fex file ( for android : lichee/tools/pack/chips/sun7i/configs/android/wing-nck70/sys_config.fex) all are explaine on the file.

For me I configure a LVDS sceen : AMPIRE AM-800480R3 and it work perfectly

Philippe

Title: Re: LVDS signals
Post by: ph.fouquet on January 27, 2014, 10:45:27 AM
Great info

I find on sunix.org a good description for fex file that can help you

http://linux-sunxi.org/Fex_Guide

Philippe
Title: Re: LVDS signals
Post by: herter on January 27, 2014, 10:36:08 PM
Thank you for your replies.

I totally agree with you Philippe, it was what I thought.
Indeed I saw on this website: http://www.allwinnertech.com/en/product/A20.html (http://www.allwinnertech.com/en/product/A20.html) that the A20 can support the LVDS.
Unfortunatly, I can't open the schematic and so your link on Github.
As dave, I would like to load it into Altium.
When you mentionned TTL, you mean 3.3V?
Title: Re: LVDS signals
Post by: ph.fouquet on January 28, 2014, 09:27:15 AM
Sorry It a wrong thing I put eagle scenatic link but it's better with pdf : https://github.com/OLIMEX/OLINUXINO/blob/master/HARDWARE/A10-OLinuXino-MICRO/A10-A20-OLINUXINO-MICRO-4GB_Rev_D.pdf

TTL signal is 3.3V to ground with 8 bits by color ( red, green and blue)
LVDS signal is 4 or 5 differantial paire and the rgb data are mux in this signal
Title: Re: LVDS signals
Post by: herter on January 29, 2014, 05:25:43 PM
Ok thanks Philippe.
By the way, what kind of connector can i use behind the screen in the LVDS connector?
Indeed, I want to avoid to weld directly wire for each LVDS signal.
Title: Re: LVDS signals
Post by: ph.fouquet on January 29, 2014, 05:46:07 PM
The LVDS connector depends of your screen (one screen on connector), it's very bad.

I just can say you to use twisted pair for aech signal VPx/VNx

that my connection :

(https://doc-0o-a4-docs.googleusercontent.com/docs/securesc/9l8t6t7vpvefefj0meshfmruda2lamnu/aq9dmph1q8ut9kg6pm42argc8q28f2rv/1391004000000/10214600545988584496/10214600545988584496/0BzB_M_u_IizEbzZSX1VMc1NCaEU?h=16653014193614665626&e=download)

Hight res : https://doc-0s-a4-docs.googleusercontent.com/docs/securesc/9l8t6t7vpvefefj0meshfmruda2lamnu/fp88ho8n04igj12buog3un7l2iqcdbs3/1391004000000/10214600545988584496/10214600545988584496/0BzB_M_u_IizEVUVXWkxaTVV3TGc?e=download&h=16653014193614665626&nonce=sfbsfpq58ak4e&user=10214600545988584496&hash=nka0uqn3380ncki73ieidvlrf78nkdri

Philippe
Title: Re: LVDS signals
Post by: herter on January 30, 2014, 03:21:22 PM
Yes I agree with you but I can't open your link:-\.
How can i do that?
Title: Re: LVDS signals
Post by: ph.fouquet on January 31, 2014, 09:42:12 AM
You can at https://drive.google.com/folderview?id=0BzB_M_u_IizEemJzSmpBdmpVbWs&usp=sharing

philippe
Title: Re: LVDS signals
Post by: herter on January 31, 2014, 10:03:44 AM
Ok thank you very much Philippe.
I will find the good connector for my screen.
Title: Re: LVDS signals
Post by: SaabFAN on February 01, 2014, 02:47:36 AM
What is the maximal length of the cable that connects the screen to the board?
I am looking for a low power display and computer to build a computer for the yacht of my parents. The distance from the computer to the display would be 1Meter at max.
The environment is also not really free of EMI, as the engine instuments (analog instruments with unshielded cables connected to the engine) will sit right next to the box where the computer is housed. The engine-bay itself is separated by a bulkhead from the area where the computer is housed (boat is made of Aluminium).
Title: Re: LVDS signals
Post by: dave-at-axon on February 01, 2014, 07:04:08 AM
If your cable is only 1 meter, then just run with the HDMI output and save on the need for using and configuring LVDS. I've run this at 3M without any issues at 720p. If the monitor you have is DVI only, use an LVDS to DVI cable.