Motherboard LVDS port type: The invisible pink unicorn.

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Motherboard LVDS port type: The invisible pink unicorn.

Postby Oddware » July 14th, 2017, 4:34 am

Hi. Sorry about the mythologically inspired sub-title, but it about sums up my experiences so far identifying the LVDS port on my Asus N3050T thin-itx motherboard.

Long story short, identifying the physical port type on my motherboard, and by extension finding the correct connector I need to buy to mate with it, has been holding me back for months.

I figured the port must have some identifying nomenclature, e.g. the humble kettle lead connector is IEC_60320#C15. But it's proven to be a double blind search, with only vaguery to guide me.

The manual only says "LVDS". The manufacturer says "Standard 40 pin LVDS", neither of which gives me decisive search results. I needed a type name. A part number. Something. Anything.

I pestered the manufacturer for more information, but that lead me a merry dance to nowhere, ping-ponging back and forth between various computer stores (which don't deal with this mythical LVDS stuff).

All roads lead here. Umm...Help?

Cheers. :)
Oddware
 
Posts: 2
Joined: June 23rd, 2017, 3:20 pm

Re: Motherboard LVDS port type: The invisible pink unicorn.

Postby bandersnatch » July 15th, 2017, 4:27 am

Hi,

Welcome to the bleeding edge of cable compatibility hell ;^)

Strictly speaking, LVDS only defines a generic differential voltage interface and not a cable pinout assignment.

As you already know, the wide range of different TFT displays has resulted in a bewildering collection of non-standard "standard" LVDS cables

The cables are specific to each series of TFT display, so you gotta first decide WHICH "LVDS" TFT display you want to connect...

IMHO, you then have problems at 2 ends:

1/ Connector type/dimensions & pinouts at the ASUS mainboard
2/ Connector type/dimensions & pinouts at the TFT display
- If you already have a TFT display then search backwards for a "Standard 40-pin LVDS cable" for this display
- Search for the display number only & check out the specs/pinouts for other systems/projects using this display

If you cannot find the right cable for your display then you are gonna have to "hack up" your own cable..

First gather information...
Good starting places are:
https://sites.google.com/site/lcd4hobby/lvds-cables
https://sites.google.com/site/lcd4hobby ... -pin-cable

G$$gle for "Standard 40-pin LVDS cable pinouts"
G$$gle for "Standard 40-pin LVDS cable images"
Search for "40-pin LVDS cable" at alibaba
- You will see that most of the cables have the same type of connector at one end (IPEX connector)

1.1 ASUS Connector type/dimensions
First step is to find SOMETHING that mechanically fits the ASUS socket
I'm only guessing, but many LVDS interfaces use IPEX connectors
Measure the dimensions of the connector/pin spacing on the mainboard
Compare with the specifications for a 40-pin IPEX connector

Whatever... you gotta start somewhere & if the mechanical dimensions seem correct then
take the plunge and just buy the cheapest 40-pin IPEX LVDS cable with the most wires coming out of it & see if it fits,
if not you can always send it back (!)

If it fits then you are 1/4 of the way there...

1.1 - ASUS Connector PINOUTS
Use a multimeter, crocodile clips and needles to identify the GND pins at the ASUS connector
Compare these with the lcd4hobby LVDS cable definition above.
If all GND pins match up, the chances are pretty high that the other pin definitions are also correct
(Yeah, I know this seems a bit micky mouse, but this is a statistically valid approach ;^)))

Identify the LVDS controller chip (probably the square IC directly next to the connection)
& search for "App notes"/projects/cables for this chip

2: TFT display
- If you are lucky, you will find an LVDS cable for this screen with an IPEX connector at one end
and matching plugs for the TFT screen at the other end.

If not, then you will have to dig up the signal specifications for your display
Match up the various pin assignments for the signals
Rewire the cheap cable you purchased above...


Search hackaday BLOG/forums for "LVDS". There are numerous postings/articles on this topic...

As usual, all these suggestions are provided without explicit or implied warranty ;^)))

I hope this helps..

STFB
bandersnatch
 
Posts: 150
Joined: September 17th, 2014, 12:06 pm

Re: Motherboard LVDS port type: The invisible pink unicorn.

Postby Oddware » July 17th, 2017, 2:11 pm

Well, I do have half the equation potentially solved. The screen I intend to use is salvaged from a laptop (complete with cable). So if there's any cable hacking needed, it's only at one end.

As for pin-out, Asus did give me a diagram for that. And so long as I can root out something for the display end, then electrically I should be golden.

Right now I have a hangover-esque headache, so if I come up with anything worth hearing, I'll be back.

Thanks bandersnatch.
Oddware
 
Posts: 2
Joined: June 23rd, 2017, 3:20 pm


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