na1pir
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Re: LVDS Interface

Sun Oct 30, 2011 9:14 am

This is harsh world for software developer in need of hardware knowledge and expertises... I think that I could manage one sided PCB with some help of course, but 2 sided PCB is too much for me. Almost all similar projects ended up in my drawer.
Now I see it would be cheaper to buy second hand 17" LCD with DVI in on-line flee market, they come as low as 30€.

gsh
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Re: LVDS Interface

Sun Oct 30, 2011 12:07 pm

The best solution would be a standard LVDS transmitter hooked up to the DPI output...
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jmg123
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Re: LVDS Interface

Sun Oct 30, 2011 12:10 pm

If the person who designed the board doesn't mind, and it will fit in a 5cm*5cm square, then seeedstudio would be able to produce them for $9.90 for 10 pcbs ( volume prices of 50, 100 will be even cheaper) this is for 2 layer silkscreened pcbs, i have used them before, the boards look great.

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abishur
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Re: LVDS Interface

Sun Oct 30, 2011 2:21 pm

@gsh do you know how to do this? I tried to google it a while back and came up pretty empty for my efforts.

@jmg, I don't think he'd mind, but the board is 5.7 cm wide and 3.7 cm tall
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Skygod
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Re: LVDS Interface

Wed Nov 02, 2011 12:23 pm

My understanding is that a MIPI DSI output is to be available, so the TC358764/5 DISPLAY BRIDGE MIPI® DSI to LVDS from Toshiba might be an alternative to the TI chip

http://www.toshiba-components......65XBGA.pdf

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abishur
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Re: LVDS Interface

Wed Nov 02, 2011 8:02 pm

I saw that one too, but I can't find any place that actually sells it. It might also be an issue that its BGA. (i.e. you'd need special equipment to solder it)
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Skygod
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Re: LVDS Interface

Fri Nov 04, 2011 5:50 am

I've been thinking of an alternative approach. Maybe just have a small screen for 'mobile' use and use the HDMI / Analog interface back at 'home'.

As there is a MIPI DSI output, do you think it would be feasible to connect up something like a 3.5" 800 x 480 screen directly?

http://www.sii-components.com/.....VF0H_E.pdf

The Driver IC for this is an LG4573 which appears to take a MIPI DSI input.

I so badly want a screen solution for the Raspberry Pi, I'm trying as many alternatives as I can.

tidalwave
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Re: LVDS Interface

Sat Nov 05, 2011 2:46 am

So the TFP401A converts the DVI/HDMI signal into TTL and then the SN75LVDS84A converts that TTL signal into LVDS for LCD consumption. This would be perfect for both groups of users in that some smaller LCD panels have TTL input i.e. a PSP LCD and laptop LCD's mostly have LVDS input.

I think I am definitely gonna look into this and if it seems plausible I might try and get a few boards assembled.

nullstring
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Re: LVDS Interface

Tue Nov 29, 2011 4:49 pm

Any update on this topic?
Also do we know if the MIPI DSI was scrapped or not?

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glenn66
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Re: LVDS Interface

Tue Nov 29, 2011 11:26 pm

For the cheapskates out there...

http://rgwni.blogspot.com/2011.....nough.html

Just last week I got 2 7" monitors for roughly $20 on eBay that were part of a dead in-car DVD system and I have a 7" resistive touchpanel (complete with USB interface) I got for about $15 so that's about $25 for a basic 7" touch monitor that should work with the RPi.

It tests out beautifully with TinyCore (running on a netbook) at 400 x 300 px resolution as a dashboard head unit for a car computer. Nice big icons for tapping on the move.

roguethunder
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Re: LVDS Interface

Wed Nov 30, 2011 9:29 pm

Quote from abishur on November 2, 2011, 20:02
I saw that one too, but I can't find any place that actually sells it. It might also be an issue that its BGA. (i.e. you'd need special equipment to solder it)
http://avnetexpress.avnet.com/ seems to have it listed, but not in stock or priced(a get-a-quote-for-price note...) Albeit I'm USA so I was poking through their USA site.
http://www.arrow.com/components/ also lists it, and even gives a price of a smidge over 5$ USD. Though they don't note having it in stock.
(This is all for the TC358765XBG, not the lesser TC358764XBG. Which is probably cheaper.)

There are some tricks for handling BGA in a less-than-professional setup. Its pretty much just reflow following a set thermal curve--and anyone who has followed hack-a-day for long enough should know some hardware-hacker methods for said ^.^' Though how sensitive a specific module is and how fine its BGA pitch is does effect how easy it is.
... unfortunately the TC358765XBG and TC358764XBG look to be *extreamly* fine pitch...

^.^ Oh well. One step forward, one step back. Progress but in an odd tangent.

On an odd tangent, anyone have any idea what interface the Iphone 4's screen uses? The LCD's themselves are rather cheap. But unlike the 3gs no-one I can find has figured out it's interface(or put much effort into it)...

Skygod
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Re: LVDS Interface

Thu Dec 01, 2011 11:48 am

Quote from roguethunder on November 30, 2011, 21:29
On an odd tangent, anyone have any idea what interface the Iphone 4's screen uses? The LCD's themselves are rather cheap. But unlike the 3gs no-one I can find has figured out it's interface(or put much effort into it)...

Being that it's Apple we're taliking about, it's probably going to be something 'different'.

Could well be 'DisplayPort Embedded' or eDB.

Anyhow, it looks like the days are numbered for LVDS.

http://www.brightsideofnews.co.....p-v13.aspx
eDP is primarily geared towards embedded applications, most notably in very thin displays. As displays get thinner and more power saving, things like eDP will become more attractive. The benefits of eDP have been detailed in the past, including stuff like less wires needed to transmit a higher bandwidth signal while still consuming less power than Low-voltage differential signaling (LVDS) technology.

eDP can be seen as a mobile standard, but in reality its benefits are easily utilized across the computing spectrum and as such will not only improve mobile computing, but almost any type of computing that uses a display today. We might even see an eDP in some embedded computers that are integrated into displays, such as all-in-ones. As stated in the past, all of the obvious benefits of eDP have driven many people to expect eDP to replace LVDS in the coming years.

Last December, Intel and AMD announced that in the next three years the two companies would no longer support LVDS, but rather focus on lower power digital signal interfaces like eDP. As a result of this announcement, vendors like Dell, Lenovo, LG, Phillips and Samsung have promised to follow the same timeframe of phasing out LVDS. The slow but gradual shift away from LVDS will benefit consumers in ways that they are not likely to see, but yet again will help manufacturers create higher quality products at lower prices.

Overall, these announcements are ones that we expected VESA to be making regarding DisplayPort. We're glad to see that VESA is constantly improving as the technology develops, making sure there are no weak links in the chain (like LVDS). We look forward to hearing more developments regarding DisplayPort in the future and expect to see more adoption as 2011 and 2012 roll by.

bobdvb
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Re: LVDS Interface

Fri Dec 02, 2011 4:26 pm

I have access to a few 'spare' LVDS panels and in particular a nice 32in HD panel with no processor board which I wanted for a home brew project. I've been looking around and I found a converter from DiamondPoint http://www.dpie.com/lcd/ but their price is higher than NYTouch so I might see if I can get one from NYTouch if they are cheaper.

roguethunder
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Re: LVDS Interface

Sat Dec 03, 2011 5:44 am

Quote from Skygod on December 1, 2011, 11:48
Quote from roguethunder on November 30, 2011, 21:29
On an odd tangent, anyone have any idea what interface the Iphone 4's screen uses? The LCD's themselves are rather cheap. But unlike the 3gs no-one I can find has figured out it's interface(or put much effort into it)...

Being that it's Apple we're taliking about, it's probably going to be something 'different'.

Could well be 'DisplayPort Embedded' or eDB.

*shrug* The iPhone 3gs used a *Very* standard interface, MPL I think it was... though the folks playing with them have been a bit buried in the depths of the internet, but they had them working with a project usable interface board. And I would suspect its nothing apple special since its *Samsungs* chips really with hardly any modification to them themselves.
Only reason I perkulate the thought is that the Iphone 4's screen is *unusually* affordable for a VGA+ small screen and could be great for projects if someone figured out how to interface it. (Often under 50$ with touch layer included. Sometimes as little as 30$. Scarily good for a 960x640 3.5in screen.)

MystX
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Re: LVDS Interface

Tue Dec 06, 2011 3:24 am

@abishur
Would you be able to get the NC drilling file for your friend's PCB, or some more info on the components on the board other than the two chips?
I think I might get some of those boards made at batchpcb.com for a few LCDs I have laying around.

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abishur
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Re: LVDS Interface

Tue Dec 06, 2011 4:43 am

Unfortunately I've uploaded all the files I have available. If you can find some way to use portel then it has a fairly extensive listing of components I believe.
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MystX
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Re: LVDS Interface

Thu Dec 08, 2011 10:30 pm

OH I see what- wow now I feel silly.
I have Altium 10 at home (which I think used to be Protel), but I've been trying to open the autocad file. Was in too much of a rush.
Ok, I'll try opening the Protel file when I get home.

MystX
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Re: LVDS Interface

Sat Dec 10, 2011 12:43 am

@abishur
I get the impression that the EEPROM your friend used requires programming =(
It'd be great if you could ask him / get the code off him. This circuit is a little too complex for me =(

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abishur
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Re: LVDS Interface

Sun Dec 11, 2011 5:50 am

I'll shoot him an e-mail in the morning it might take a while for him to respond.
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abishur
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Re: LVDS Interface

Sun Dec 11, 2011 4:56 pm

Sent off the e-mail, I'll repost when he responds
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abishur
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Re: LVDS Interface

Mon Dec 12, 2011 12:22 am

Here's the e-mail I got back from him

I used two programs to create and then write the EDID data to the EEPROM.
I used Phoenix EDID Designer to create the EDID data file. It's just a nice intuitive GUI for creating the data file. Piece of advice, you always need at least one of the 'standard' display resolutions (640x480, 800x600 etc). I just chose the one that was closest to my resolution, ie my panel was 1024x600 so I chose 800x600.
I then used EnTech PowerStrip to write the file to the eeprom. This is a bit of a fiddly process as you have to be super careful not to overwrite the EDID to your main monitor. So what I did first was check what searching for EEPROMs and reading the EDID info did without my homemade panel plugged in, as this then lets you know what location/address your actual monitor is on. Then I plugged in my homemade panel in and did it all again, this time PowerStrip found two devices (one blank), which all makes sense. Having found the ID for the homemade one I then pushed the EDID data file out to it, and it worked! You may have to unplug it and plug it back in or even reboot once you've written the EDID data to it to get windows to recognise it.
Good luck!
/End of his response

I hate to admit this, but I understood very little of what he was just responded so I can't offer too much in the way of further assistance, but if anyone does use this method and work it all out, I hope you doing a lot of documentation so others like myself can replicate your results.
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MystX
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Re: LVDS Interface

Mon Dec 12, 2011 3:35 am

Aaaaah ok.
I was under the impression that the EDID was on the screen, and was all handled internally. From what I gather from his email, he stores the EDID on the EEPROM, and whatever device is trying to access the screen (R-Pi in this case) talks to that to get the screen info.
I could be wrong though =\

bobdvb
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Re: LVDS Interface

Mon Dec 12, 2011 10:39 am

'Source' devices like PCs or STBs interrogate the EDID of a 'sink' device (monitor) and because the panel itself is dumb the interface used with it can take the EDID config from the EEPROM and use it to define the settings for the panel. Its actually quite a cunning design, you don't need to write the EDID with the RPi, you only need do it once on a PC running the above mentioned software. After storing the configuration values for the scaler it will use the EDID to feed the panel.

MystX
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Re: LVDS Interface

Mon Dec 12, 2011 9:13 pm

Ah. I realised late last night that you only had to plug in the finished board to program the EEPROM. I thought that I'd have to make up a programming cable + board and wasn't too keen =P

Awesome! It sounds like I'll definitely be able to pull this off. I've ordered 5 of the boards from batchpcb.com - it ended up costing around $50USD + shipping, not bad.
Soldering those ICs is going to be fun!

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abishur
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Re: LVDS Interface

Tue Dec 13, 2011 1:50 am

Could you explain that please? EEPROMs are outside my knowledge realm and I admit I don't understand the process for getting that part working :)
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