color lcd modification

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deepak007

Joined: 20 Sep 2007
Posts: 89

04 Jul 2008 8:32 color lcd modification

hello

can any one tell me how to modify a color lcd (taken from a cellphone or video game ) to receive and display a video camera output. that means tell me how to convert any lcd into a monitor. please help.

RossiRPI

Joined: 14 Feb 2007
Posts: 35
Helped: 2
Location: South Africa

04 Jul 2008 9:48 color lcd modification

Hi

Depends on the LCD display. The problem is that you will have a different controller for a different LCD. This means that the way the LCD accepts the image is different from LCD to LCD.
Do you have a psecific LCD in mind?

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deepak007

Joined: 20 Sep 2007
Posts: 89

04 Jul 2008 10:02 Re: color lcd modification

hello RossiRPI,

thanku very much for your help.lets take sony ericsson k750i lcd. what are the modifications to be made? or if u have any other lcd's with modifications,please name them tell me the modifications.

RossiRPI

Joined: 14 Feb 2007
Posts: 35
Helped: 2
Location: South Africa

04 Jul 2008 13:06 color lcd modification

Well, first of all check this page http://sandiding.tripod.com/lcdk750.html . It gives you information for the specific LCD and its controller. You then need to get the datasheet for the LCD controller.
After you have done the following you need to figure out how to convert the signals from the VGA source into images for the LCD display.
Then you need to decide what microcontroller you will use to controll the LCD, it must be fast enough to be able to decode the VGA signal and drive the LCD at the same time!

I beleive that it will take you ages to get this right if you have no idea what you are doing! You can get all the info you need from google.

I have only seen people drive VGA with a microcontroller, not visa versa which is what I think you want to do. Though I am sure that it will be easy enough to work backwards and drive an LCD with a VGA signal. I'm not sure if its worth it though.

Added after 2 hours 50 minutes:

Ok... basically you are going to have two units.
The first will be the camera and transmiter unit and the second will be the receiver and the LCD.
You do not have to worry about VGA signals or anything like that.
You will have to see what kind of image you get from the camera and how to display it on the LCD. you will probably have to go into compresion techniques or just figure out how to translate the camera data into an RGB image.
You also have to decide what technique to use for woreless transmition. I mean u get simple 433Mhz transmitters and then you get 2.4Ghz zig-bee and x-bee. I would say the ST CC2430 is a good choice. its a 2.4GHz zig-bee tranceiver.

You need to decide if you want full video or just pictures. If you chose to transmit video you will need a pretty powerfull processor and complicated software.

do you want the receiver and LCD unit to be moble? if so you need to get a decent batery...

This is not going to be an easy project and I am not sure that its the best thing for someone who does not have much experience with embeded systems. though if you want a chalange go for it.

deepak007

Joined: 20 Sep 2007
Posts: 89

04 Jul 2008 13:36 Re: color lcd modification

thanks once again!

i have a small doubt. suppose take the sony ericsson k750i cellphone. if we copy a video song into its memory and play it, it plays. right? it has to take the data from the storage chip and play it. there is a bus connection between the lcd and storage. there is a software which plays the music. now if we couple the cameras video signal (using a to d converters if necessary)at the storage chip leads or some where in between. i don't know where exactly. got the point? the video cameras signal will be coming out continuously and gets coupled to lcd bus, and reaches the lcd through its own compressors and processors and gets displayed. this is a general idea. forgive me if i am wrong.

RossiRPI

Joined: 14 Feb 2007
Posts: 35
Helped: 2
Location: South Africa

04 Jul 2008 13:44 color lcd modification

Hm... I wish it was that simple!!! You see the memory you are talking about only holda a single image. It does not actually contain the whole video.
The video is stored in flash memory on the selphone. The cellphone's processor then reads the video, processes the video and audio and sends the apropriate data to the LCD and speakers!

A video signal is not just one wire! you get little camera's which have a digital output. All you have to do is read the image, process it and transmit it. Then on the LCD side you have to receive it and send it to the LCD. If you can do this about 25/30 times a second you have video.