using digital input, not analog?

If you're making a portable you probably need something to watch it on. (Unless you want to guess what's happening in the game, but I wouldn't advise that) Anyway, this forum is your "Hacking a pocket TV/screen" one-stop solution. Share your experiences and knowledge here.

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Suicicoo
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using digital input, not analog?

Post by Suicicoo » Fri Apr 23, 2010 11:21 am

i(think;) I) have to explain a bit, before asking the main question:
i plan on building a minilaptop from a dmg-case and a beagleboard(better: igepv2 board) and this screen

i've already read about the 3,5" car-lcds you recommend for modding and want to ask if it is/was possible on any of these screens to use a digital or vga input and no common video signal? i know the BB is capable of giving s-video-output, but i like the idea of using a digital/vga signal better than s-video
many thanks in advance - sui :)

tom61
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Re: using digital input, not analog?

Post by tom61 » Fri Apr 23, 2010 11:43 am

The current BeagleBoard has an integrated LCD controller, so you can run a bare LCD display, which should be cheaper.

Very odd advertising on the display linked, the inputs for it are analog. The TFT takes digital signals, but not the display as a whole.

Suicicoo
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Re: using digital input, not analog?

Post by Suicicoo » Fri Apr 23, 2010 12:06 pm

these displays are all like this, because they are meant for backwards driving cams in the first place(which only give analog signals, i think)

Suicicoo
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Re: using digital input, not analog?

Post by Suicicoo » Thu May 06, 2010 1:09 pm

i now own the screen and did take it apart to have a look at the insides...
is anybody able to help me defining the soldering points in the upper right corner?
what could i do to find out, what they are for?
Image
Image

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OMGpedobear
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Re: using digital input, not analog?

Post by OMGpedobear » Fri May 07, 2010 10:44 am

You will not be able to put vga in that screen without a convertor, your stuck with composite or you will have to buy a very expensive and big vga to composite converter (can the beagle board even output vga? Also vga isn't digital just so you know) Try it on compsite , if things are readable and its all ok stick with that, if you want more clarity look into driving a psp screen directly from the beagle board, ive heard it can be done with no extra hardware, also psp screens are a whole lot thinner. I attempted a project almost identical to this about half a year ago but i ran out of money and used the parts else where, so goo luck! And take lotsa pictures :).

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OMGpedobear
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Re: using digital input, not analog?

Post by OMGpedobear » Fri May 07, 2010 10:59 am

did some a googlin on the techwell tw8817 chip, looks as if it is the display driver chip, the data sheet says it can accept s-video, which the beagle board natively supports, so theres a little improvement in quality. Another thing it says in the data sheet is that this chip has 2 wire serial probably used for configuration so that connector top right is most likely for loading settings and or firmware over serial, you probably need to use this should you want to go down the s video route. Also, looking at those pictures, you should be able to extend wires to the caps and put them in the bottom half and keep the top half , complete with driver board nice and thin.

For a keyboard have a look at the clip on wireless usb ps3 keyboards, they are quite cheap and the buttonsand top half of case could be franken cased onto your mini laptop. Another thing you may want to consider is one of these:

http://www.sparkfun.com/commerce/produc ... ts_id=9320" onclick="window.open(this.href);return false;

touchscreens are very expensive and to be honest dont work that well on such small screens, so a rack ball would be great, a pic or similar could be the interface and you could use serial from the beagle board to control the cursor, also it has kewl rgb leds under the track ball.

Last thing, batteries, use a single cell nice n flat lipo of at least 5000 mah and a 5 v boost inverter designed for running rc cars on single cell to power everything.

and good luck again, oops double post :roll: .

tom61
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Re: using digital input, not analog?

Post by tom61 » Fri May 07, 2010 11:10 am

The upper right looks like a JTAG header, likely used to test out the chips and to program it to use the signals of the country it's bound for. If you want to drive it directly from the Beaglboard's controller, you need to create an adapter the goes from the ribbon cable (you'll need to look up the datasheet with the number on the LCD panel itself) to the Beagleboard, and then setup up the software to use it (my guess is a X11 modeline needs to be created).

OMGpedobear: IMO, touchscreens work decently well on anything smaller than 9", so long as they are calibrated.

Suicicoo
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Re: using digital input, not analog?

Post by Suicicoo » Tue May 11, 2010 11:21 am

oh, some movement here :)
thanks for the answers!
@omgpedobear: yeah, i was aware, that vga is not digital, thats why i asked if digital or vga would be possible - in the german forum i usually roam, someone told me, it would be at least possible to use s-video instead of composite(thats the 2-wire-signal, right?) to improve the image-quality
i thought about a psp-screen, but the resolution is almost half the one i now own :)
i didnt want to use a touchscreen, they are a terrible invention and should be... ...lets just say, i hate touching around at my screen
for the ps3-pads do you know if they hook up to the ps3-controller-signal and are therefore 'wired'(to the controller at least) or do they directly connect to the ps3?
the trackball is a really great addititon i could possibly make, i planned using a small usb-mouse... we will see
i didnt really intend on using some battery, as i dont like them and will mostly be using the 'laptop' at home - as a ... mediacenter like thingy and for surfing the web without having to power on the bigger devices
as for the heigth of the screen: the whole thing with case would easily fit in the top half of a dmg-screen, so there will hopefully be no need to seperate the screen and the board(but maybe i find out, if the beagleboard is able to directly input to the screen to do, what tom61 suggested)

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OMGpedobear
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Re: using digital input, not analog?

Post by OMGpedobear » Wed May 12, 2010 1:05 pm

Yeh s video is the 2 wire interface, ill post again when i have a bit more time :D.

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