[HACK] LVDS on Rev B Beagleboard

Hello,

I thought I'd share a little hack I put together back at the end of
September for a Rev B Beagleboard, in case anyone's interested. I
hadn't got round to uploading the pictures at the time (and forgot
since then) but I think LVDS-on-Beagleboard will get get more topical
again this month with the release of the excellent RevC update with
the OMAP3 LCD outputs available.

So....

The aim of the project was to drive an LVDS TFT panel directly from
the Beagleboard, *without* first going to DVI, then externally
converting to LVDS (IMHO icky). The LCD panel was an AUO B089AW01,
which is the 1024x600 18-bit colour TFT featured on several of the
netbooks available (e.g. Acer Aspire One).

General plan:

o Remove TFP410 DVI serialiser.

o Use buffers to step the 1.8V OMAP3 LCD outputs up to 3.3V.

o Use a NatSemi DS90C363 LVDS serialiser to drive three LVDS pairs
(plus one clock) to the TFT panel.

Total cost: about 10UKP of parts (3xSN74AVC8T245 octal buffers (dual
power rails), 1xDS90C363, misc connectors/passives) plus a small PCB
(homemade in kitchen with Iron-On(TM) toner transfer technology) plus
time. (A lot of time. You'll see the soldering below; it was
enormously enormously time-consuming.)

So, it's not pretty but it works, as the saying goes.... >:-) Anyone
want to see?

Here's the board:

  http://axio.ms/photos/BeagleBoardLVDS/LVDSBoard.jpg

Here's the space once occupied by the TFP410, with 33 gauge wirewrap
wires being soldered on (apologies for the crappy picture quality).
The flux is making it look a little messy, but it cleaned up.

  http://axio.ms/photos/BeagleBoardLVDS/Loupe.jpg

The umbilical wires in place:

  http://axio.ms/photos/BeagleBoardLVDS/Wires.jpg

Finally, the two welded together:

  http://axio.ms/photos/BeagleBoardLVDS/AttachedToBB.jpg

Naturally I forgot to take a final shot before it got whisked away
abroad (d'oh! :slight_smile: ), but it worked splendidly. I believe the prototype
photos of a certain OMAP3-based device announced this week are it in
action.....

Am looking forward to (I think Keith Williams's) revC daughterboard.
One thing to note is that most LCDs will require a lot of current on
the 3.3V rail and will require an extra 3.3V power supply/regulator
from the BB's 5V supply; software side of things was easy, and it was
a lot of fun. :slight_smile:

Hope that is of some interest,

Matt

Thanks Matt. This is a very interesting contribution!

What kind of connector do the B089AW01 screens come with? Actually, do
they come with a connector or just an FPC cable?

Hi Andi,

The B089AW01 has an IPEX 20347-340E-12 connector on it; I hacked
apart a cable from an Aspire One, which appeared to be custom-made (by
Foxconn IIRC). It was composed of a set of insanely tiny coaxial
cables (I'd guess near 30AWG!), with hair-thin conductors :
( (Soldered onto 2mm pinheader connector at 'my' end.)

If I had just the raw panel, I would've desoldered the connector &
soldered wires onto the board direct; I remember having trouble
finding the matching connector/plug from the usual sources (e.g.
Digikey, Farnell, RS, etc.).

Matt

As stated in the datasheet of the screen, it's an IPEX connector.
Unfortunately, unless you are a manufacturer in Taiwan or Shenzhen,
it's very difficult (=almost impossible) to get it,

Grégoire

What are the two smaller cables with little plastic connectors
branching out of the main Aspire
one cable?

If anyone has some kind of data sheet or pinouts for this cable
(either the DD0ZG5TH100 or
the DD0ZG5TH300) *please* email it to me. I really need this info
because I already have this
particular panel and I can't buy another one with widely available
components...