Topic: LVDS 54 conductor flat cable

Has anyone come across a source for a cable to connect things to the 54 conductor LVDS header on the Novena.  It really looks like 54 is outside the range of "standard" assemblies.  I found this site that offers cable assemblies, but tops out at 50 conductors: http://www.quadrangleproducts.com/category.cfm?c=52

In looking at many other sources of cables 50 seems to be the normal cap.  Perhaps the only solution is a custom flex board?

2 (edited by projectgus 2015-01-20 04:22:45)

Re: LVDS 54 conductor flat cable

Hi GregRob,

I've noticed the same thing. I guess the expected cable to use is the custom designed FPC (Flexible Printed Circuit) for the Novena LVDS interface, rather than generic FFC (Flexible Flat Cable). Custom flex PCBs seem pretty common for modern LCDs.

To test my "Novepad" adapter board prototype I got a generic 50 pin FFC from taobao (the same are on ebay, I think). The endmost 4 pins of the 54 are just used for the resistive touchscreen signals, so as long as you place the 50 pin cable at the right end then all the important signals should still be connected. You can kind of see this in the photos on the "iPad 3" thread.

There is a chance that the generic FFC won't be good enough as all the conductors are the same width & spacing. There could be signal integrity problems with the LVDS pairs or current draw problems with the power pins. The Novena LVDS FPC has routed pairs for each LVDS signal, and thick copper sections for power/ground. I'm hoping that with a short cable things will still be OK, though.


Angus

Re: LVDS 54 conductor flat cable

Can anybody suggest a good vendor for producing small quantity FPCs?  Or Bunnie: will there be any opportunity to purchase the short FPC cable from Kosagi? 

At the moment I am using a HDMI to LVDS LCD converter board with my LCD screen, but would like to skip that and interface to the LVDS port directly.  My thought is to make a simple breakout board to expose some of the 54 conductors to a header compatible with my existing LVDS cable, and likely make the rest available for other hacking.

4 (edited by mclien 2015-02-09 23:18:15)

Re: LVDS 54 conductor flat cable

I'm relativly new/noob on this aera, but as I understand it we need a custom, flexible PCB with the correct wiring (for each LCD we come across)?
Or is the one that comes from the LCD pannel somehow standard (as in same on all LCD pannels out there)?
In any case, if someone can do the layout I can give it a try at the company my wife works... (just like the senoko boards)
The FPC that came with the "just the board" pledge is for a different purpose, or did I got something wrong?

5 (edited by GregRob 2015-02-10 01:01:26)

Re: LVDS 54 conductor flat cable

I think the FPC you are referring to, which comes with the boards, is the ROMulator Breakout Board, as described in Stretch #3 in Bunnie's blog post on the Novena Stretch goals: http://www.bunniestudios.com/blog/?p=3750

My thought on the display ribbon cable was to get from the 54 pin Molex header on the main board to another board where I could then interface to the cable which I have that plugs into my LCD panel.  From what I have seen there is not a standard for LVDS panel cables.  This kit from Digikey seems to be built around customising cables for LVDS driven LCD screens, although even there the connector width can vary, with 4 versions of the kit being available: http://www.digikey.com/us/en/ph/JAE/LVDS.html

Re: LVDS 54 conductor flat cable

Ah thanks for the enlightment to the ROMulator Breakout Board.

to the LVDS connector:
After looking a bit into it, I agree. I know that at the company my wife works for, they can produce PCBs that have a flex and a rigit part. Let's say we get a flex cable there that has the 54 Molex end and a rigit PCb, which is capable for hand soldering wires. That way we could use the mentioned digikey LVDS kit.
AND if I see it correctly these kits come with quite long cables and 2 simmilar connector. So with 2 flex cables and 1 digikey kit, we could make 2 "Novena LVDS kits" by cutting the cables in halves and use on half of the cables and one connector for each kit.
If someone can design the PCB for that I would happily co for the production (like I did for the senoko boards)

Re: LVDS 54 conductor flat cable

Found this on ebay:

http://www.ebay.com/itm/Sintech-5PC-AWM … 1677297869

Theoretically it should fit

Re: LVDS 54 conductor flat cable

In case anybody wondering - the cable fits fine.

Re: LVDS 54 conductor flat cable

I posted this previously on http://www.kosagi.com/forums/viewtopic.php?id=152 , but Toby electronics carry suitable cables here http://www.toby.co.uk/content/catalogue … xx-A-xx-xx which work fine. FFC5-54-A-46-8-4-54 in particular was OK for me.