HDMI->LVDS converter

36 posts   Page 1 of 2   1, 2
by godFather89 » Mon Jul 02, 2012 8:00 am
What would be the demand for an HDMI to LVDS (serial RGB + sync) converter?
I made one home, it works and I was wondering if there is a demand for such a thing.
If there is enough demand (>250 pcs), I would interest at manufactureres for cost and get a batch of them made.
I would estimate the price/piece at 40-45$.

The main advantage (over other boards of this kind) is the size. The size for the home made PCB is small. It is smaller than the Raspberry Pi board. For an industrial made one it would be a lot more smaller.

Also note that the max panel resolution is 1280x800 (1-channel LVDS) at 24 bit color depth.
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by Norefall » Mon Jul 02, 2012 8:23 am
Im intrested. Can it run on 5V?
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by mariobaldini » Fri Jul 13, 2012 6:38 pm
Dear godFather89,

I´d also be interested in your design. Could you share the schematics? So we all can check if it fits our needs?

I think that everyone would benefit to buy it from you (made in batches), than to build it single unit.

Best regards
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by kagaku » Mon Jul 23, 2012 9:18 pm
I would definitely be interested! I have two LVDS displays at home from old laptops that I'd love to utilize.
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by godFather89 » Tue Jul 24, 2012 5:44 am
The converter actually runs from 3.3V (no regulator included yet).
I will post the schematics and the PCB drawings later.
Anyways, I don't think I'll build it.
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by mariobaldini » Tue Jul 24, 2012 8:36 pm
As it´s relatively simple to find replacement LCD parts for Ipad1,2,3:


and given their features vs price (60 - 75 USD),

maybe a project to enable it´s use on Raspberry woudn´t be interesting?

I´m not precisely sure about it´s complexity, but given the datasheets I´ve found (not exact same partnumber of Ipads one, but a very similar, from the same manufacturer)


it seems to have a LVDS interface, very similar to other regular LCDs.

Would there be other people interested in such device?

Best regards
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by GxFlint » Mon Jul 30, 2012 12:12 am
I would definitely want one.
That and a 3D printed case would make a great thin client.

If it all works out, maybe I get a few hundred more ;)
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by rabidsnakemonkey » Mon Jul 30, 2012 7:53 am
I totally want one. Let us know if you end up doing this!
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by cltcprd » Tue Jul 31, 2012 1:52 am
Totally want one
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by Rekuen » Fri Aug 03, 2012 7:29 pm
+1 I would be interested , I have a couple of LVDS monitors from laptops and it's time to get them some real use.
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by onokun » Sun Aug 05, 2012 10:02 pm
I want one too. Need to drive 1280x800 single lvds panel.
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by ceteras » Wed Aug 08, 2012 8:43 am
I'd like to mention that I'm OP's first happy customer, I've bought his alpha board and it works like a charm.
I use it with an XGA lcd panel, it has a very clear picture, as you can see in the (slightly out of focus) image below.
My currently unfinished RPi rig looks like this:
I believe the RPi can be tucked inside a laptop shell, but I don't have a broken laptop right now to do it.
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by blc » Sun Aug 12, 2012 9:04 pm
If you do plan to go ahead with this, it'd be ideal - my other half has been nagging me to get rid of my old laptop screen! :)
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by centizen » Sun Aug 26, 2012 11:40 pm
Very interested. Will this be able to use the common slimline 40 pin LVDS interface? Or will it be a different one?
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by ceteras » Tue Aug 28, 2012 8:20 am
The LVDS interface of this board is 6bit, single channel.
That translates to four lvds pairs, max resolution is at 1440x900, I think, for this kind of setup.
So yes, you can connect the board to any kind of panel sporting a single channel 6bit LVDS interface, be it 20, 30, 40 pins. I've got mine without an lvds cable, so I did the soldering mysqlf.
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by recantha » Wed Aug 29, 2012 4:05 pm
Sounds like a fantastic idea - I'd be very interested in a converter like this. I have so many displays sitting around at home... Even if just one of them works I'd be happy!
My Raspberry Pi blog with all my latest projects and links to articles
http://raspberrypipod.blogspot.com. +++ Current project: PiPodTricorder - lots of sensors, lots of mini-displays, breadboarding, bit of programming.
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by godFather89 » Wed Aug 29, 2012 4:27 pm
Here is what I've made so far (actually, the last state the project was in since I had no more time for it):

Schematics and PCB are made in DipTrace (it's free). It uses an 18 bit LVDS interface. You can switch to a 24 bit lvds by changing the LVDS transmitter. Some caps need to be added on the supply rails (they are not in the schematic, as many other things, I've added them later).
Note: The HDMI connector pins are backwards. I've fixed this making my own male->male hdmi converter which I used directly with the Pi. So the PCB will need some updates to work ok with a regular hdmi cable.
The converter needs 3.3V to work.

If anyone makes an order of PCBs, I would also be interested in one piece (maybe free for the work I've done :D )

Good luck!
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by Miguel Oliveira » Fri Aug 31, 2012 2:00 pm
Hello Guys,

I've notticed hdmi interface (http://en.wikipedia.org/wiki/HDMI) enables the pin 18 with 5V(max 50mA).

Can we use the 5v pin with a 3.3V voltage regulator to power the GodFather converter?

Anyone has tried this?

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by masehyper » Sun Sep 02, 2012 10:31 am
Hi, I'm very interested in making this converter.

While looking schemetic from godFather89, I have some questions.

1. Actually, SN75LVDS83 has TSSOP-56 package, but in this schemetics it's on sop-48.
2. In TFP403 Reference Deisgn, It has AT24C04 EEPROM, but not on this schemetic. Is EEPROM unneeded?
3. May I connect HDMI connector and N-Channel Mosfet on DDC_SCL/SDA as looks like reference design? There's no HDMI connector and Mosfet on schemetic.
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by ceteras » Sun Sep 02, 2012 11:17 pm
If you want to make the board, use "HDMI TO LVDS.dip" from the archive, it's the PCB.
SN75LVDS83 is the 56pin variant, but SN75LVDS84 (48 pin) was used on the board (and in the schematics).

The TFP403 reference design clearly states: "When using the TFP403, some board components are not necessary for the functionality of the device, such as the EEPROM. The components highlighted in RED on the following page reflect those components. "
So no, you don't need eeprom and mosfets on scl/sda for TFP403.
But if you plan to use TFP501, you will need the eeprom for HDCP functionality (playback of protected content).
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by masehyper » Tue Sep 04, 2012 10:38 am
Thank you for reply, ceteras

Now I have one more question.

Can I connect 24-bit TTL LCD Panel(NOT LVDS) directly to TFP403, Not using SN75LVDS84?

I saw some 24bit LCD Panel's datasheet like Samsung LMS480KF01 (http://icbank.com/data/ICBShop/board/(SEC)LMS480KF01.pdf).
And I thought that Connecting RGB and H/VSYNC Signal to this panel will work. Is it correct?
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by godFather89 » Tue Sep 04, 2012 10:42 am
Yes, it should work.
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by ceteras » Wed Sep 05, 2012 11:01 am
I'm not sure the 800x480 resolution is supported by the hdmi port, look at dom's post here .

Only the standard modes are supported, shown here:
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by godFather89 » Wed Sep 05, 2012 11:06 am
He can use a bigger resolution with overscan enabled.
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by powerswitch » Wed Sep 19, 2012 11:50 am

I also would buy one :)
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