Re: [Gumstix-users] LCD Specs

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Hmmm - you may want to look a little closer at the LED configuration on the
display - they are eight (8) White LED's connected in series in each of the
three strings, not a single LED per string connection (grin).

So what does this mean for your project - not too much as long as you
remember there is a forward voltage drop per LED and the eight white LED's
will have around a 22 - 25 VDC voltage drop across the string.  This is
still well under the maximum voltage rating of the MIC2297 boost LED drive
IC on the Palo-43 board.  You will need to do two things to light up all the
strings (getting past the connector issue does not count)... 1.  Connect the
three LED strings in parallel with a ballist resistor in series with each
string and 2. - Change the current set resistor on the Palo-43 board from
10-ohms to around 4 or 5 ohms to set the MIC2297 current output up enough to
power the LED strings.

You will need to get the touch-pad connections over to the Palo-43 board as
well but they will be simple - since they are separate on the LCD display
all you will need to do is connect the appropriate connections to the palo
board's connector from the LCD display touch-pad.

Most all of the rest of the signals are the same as the Samsung board used
for the Palo-43 so there should be minimal issue there...

Just a thought or two..

Now - I get around all of the above AND have a remote display in my car
using a mobile touch-screen LCD display and DVI to VGA converter running the
Overo Fire on a Summit board (grin)... gets away from all the circuit
conversions, construction of sub-atomic sized components (the eyes are not
what they used to be) and the frustrations that can go along with building
from scratch what already exists in finished form (grin).

gm...

Joe2 wrote:
> 
> Ok I hunted those down, they are under the WB4245 package name and info
> can be found here: http://focus.ti.com/lit/ds/symlink/sn74avcb164245.pdf
> they are a transceiver with level shifting. I've read a lot of people
> trying to find level shifters from the 1.8 to higher, this one will goto
> 3.3v. Any how this means the signal is coming directly form the overo com
> and is basically buffered by the level shifter. This basically goes for
> all of the signals including the touch screen. The controller for the back
> light is S142 (u11 on the board) info can be found here:
> http://www.micrel.com/_PDF/mic2297.pdf It is the MIC2297-42YML. It is
> capable of around 1~1.5 Amps. If you assume each LED string pulls 20mA by
> three parallel equaling 60mA. This is far below the current capability of
> the IC, Even if boosting to 10V roughly doubling the current draw the IC
> should be fine.
> For my application I was hoping for a 10" screen but the 7" will do. I
> would like to use two but I think that will require setting the display
> mode for a screen double in size and then splitting it with hardware. Then
> in the software controlling what gets displayed where. Thats the only way
> I see doing it at least. Now I just need to see if the summit board uses
> the same signals for the display output. Also considering that the signal
> going to the LCD is 8bits for each color it seems it would be relatively
> easy to get analog red/green/blue, Component and/or also composite output. 
> Looking at and comparing the pinout for LTE430WQ-F0C and the LMS700KF07
> they seem to be the same up to pin 34, after pin 34 the LTE430 gets the
> touch screen and the LED, the LMS700 has a pair of gronds and the rest are
> no-connects. Pin 31 is or maybe different on the two. For the LTE430 it is
> the display on/off and for the LMS700 it is Display mode which seems to be
> the power on/off but in a timed method. 
> 
> 
> Joe2 wrote:
>> 
>> Ok looking at the schematics 45 and 44 are not connected to anything. A
>> pair of flying wires could deal with that. So long as the current can be
>> handled. I'm trying to determine what U$2 and U$1 are TI.com does not
>> seem to have items 87CF3KK or 86ET79K. Knowing what they are may help to
>> understand what the signals are from the uPC are and what the signals
>> going to the display. I'm hoping to make a board if Gumstix doesn't, that
>> has both a screen interface and DVI output, so knowing what these IC's do
>> and their signals would help.
>> 
>> Joe2 wrote:
>>> 
>>> Ok looking at my 43 screen the touch screen is 4wire all the way to the
>>> palo43 board. I think the LED is pins 45, 44, 43, 42. 45 and 44 is LED 2
>>> and 43 and 42 is LED 1. 41 is a ground (I'm guessing from the layout).
>>> 40, 39, 38, 37 are the touch screen interface. 36 is ground again. 
>>> 
>>> Omer Cohen-2 wrote:
>>>> 
>>>> If you'll look a bit more, you'll find that the new model they have is
>>>> called LMS700KF07 and specs can be found here:
>>>> http://www.samsung.com/global/business/lcdpanel/productInfo.do?partnum=LMS700KF07
>>>> www.beyondinfinite.com/lcd/Library/Samsung/LMS700KF07.pdf
>>>> 
>>>> it has a the sam 40 pin spec, and two more cables, one for the back
>>>> light unit (6 pins, 2 for each led) , and a 4 pin cable for the touch
>>>> panel screen (TSP).
>>>> 
>>>> All this time I was trying to look for a screen with a 45pin, but
>>>> perhaps it's a good idea to simply build a converter to fit the 45
>>>> pin, and even use a potentiometer to control the two other leds (this
>>>> unit will eventually sit in my car)
>>>> 
>>>> Omer Cohen
>>>> www.omerc.net
>>>> ome...@gm...
>>>> 
>>>> 
>>>> 
>>>> On Tue, Aug 4, 2009 at 12:14 AM, Joe2<joe...@ho...> wrote:
>>>>>
>>>>> Ya I just dug in a little deeper and found this:
>>>>> http://www.samsung.com/global/business/semiconductor/support/brochures/downloads/lcd/brochure_psg_tftlcd_200708.pdf
>>>>> At the bottom there is the 7" and 12" screens. I found the spec sheet
>>>>> for
>>>>> the LTP700WV-F01 and I saw the same, 40 pin connector plus the led
>>>>> one. It
>>>>> does specify the connector for the 40 pin, so a adapter board could be
>>>>> made
>>>>> up easy. Comparing the 4.8 screen and the 7" The interface is the same
>>>>> 24
>>>>> bit RGB IF. Of course these are not touch screens necessarily either,
>>>>> it
>>>>> could be a easy adaptation to use a USB type on top unless we can
>>>>> figure out
>>>>> the interface via the 45 pin connector. If it is 4-wire then an
>>>>> interface
>>>>> board could combine the 40 pin and the 4-wire, but I'm not sure, I
>>>>> haven't
>>>>> looked at the palo43 spec sheet yet.
>>>>>
>>>>> Omer Cohen-2 wrote:
>>>>>>
>>>>>> I read that similar post on your blog, it gave me a lot of
>>>>>> information
>>>>>> regarding the pin spec
>>>>>>
>>>>>> I found a screen that might do the trick, LMS700KF07 by samsung, the
>>>>>> only problem I see is these new screens come with a 40 pin connector
>>>>>> for the LCD and a different 6 pin connector for the back light unit
>>>>>>
>>>>>> from what I read on the LTE430WQ spec, it has the back light
>>>>>> connectors as part of the 45 pin spec
>>>>>>
>>>>>> do you know anything about this ?
>>>>>>
>>>>>> thanks,
>>>>>> Omer Cohen
>>>>>> www.omerc.net
>>>>>> ome...@gm...
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Aug 3, 2009 at 10:57 PM, Joe2<joe...@ho...> wrote:
>>>>>>>
>>>>>>> Did you read this thread?
>>>>>>> http://www.nabble.com/Using-Samsung-800X480-LCD-with-Palo-43-td24299045.html#a24440475
>>>>>>> The touch interface is via the 45 pin connector. There are others on
>>>>>>> that
>>>>>>> ebay store that may work. I think the key would be to check samsung
>>>>>>> for
>>>>>>> the
>>>>>>> size and model screen that works for your app then find it for sell.
>>>>>>> You
>>>>>>> just need to match up the samsung pin spec to the gumstix ones.
>>>>>>>
>>>>>>> Omer Cohen-2 wrote:
>>>>>>>>
>>>>>>>> Hello everyone,
>>>>>>>>
>>>>>>>> I'm sure this question was asked before, though I failed to find a
>>>>>>>> good answer on the archive.
>>>>>>>>
>>>>>>>> I want to use a bigger touchscreen than the one offered in the lcd
>>>>>>>> pack, I need a 7"-8" one that I can fit in my car, I started
>>>>>>>> looking
>>>>>>>> online but I'm not sure how to tell if the screen I get would work
>>>>>>>> with the overo fire + palo 43 modules.
>>>>>>>>
>>>>>>>> from the docs on the site I learned that I need a 45-pin connector,
>>>>>>>> would that also control the touchscreen? anything else I need to
>>>>>>>> look
>>>>>>>> for?
>>>>>>>>
>>>>>>>> Omer Cohen
>>>>>>>> www.omerc.net
>>>>>>>> ome...@gm...
>>>>>>>>
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>>>>>>>
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>>> 
>>> 
>> 
>> 
> 
> 

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