Author Topic: 24-bit RGB LDC screen capture?  (Read 406 times)

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Offline Sudo_apt-get_install_yumTopic starter

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24-bit RGB LDC screen capture?
« on: May 22, 2024, 09:20:07 am »
Hello everyone!

I need to capture the screen of a board ive designed. The board outputs data through a regular parallel LCD screen.
Is there a conversion/emulation device one could use?

Idea 1:
Would be to convert the RGB data to some other format like HDMI and use a capture card to record the display data.
The problem is that I’m unable to find such a device, there are plenty of HDMI to RGB converters but none for the other way around.
I’m aware that pinouts can differ between LCD's and creating an intermediate/pinout conversion board is no issue.

Idea 2:
I made a similar device a few years ago that emulated and decoded the display signals to a "controller" screen and then sent the frame buffer to a computer that then recreated the screen.
It worked very well, signal speed was moderately fast and all data was sent over an 8-bit bus with some control lines. Everything was done in software with a few interrupts and some optimization.

I could do something similar for the RGB screen but it feels like i would be reinventing the wheel again. I'm pretty sure id have to dust of the old FPGA hat so id rather avoid this approach.

The screen data is generated during runtime so i can't "extract" compiled data for the screen grab.

Do any of you guys know of a device for this or any somewhat simple approach to grab the signals sent to an RGB LCD?

This is an very similar screen to the one i'm using, it is basically a drop in replacement. The difference being the FFC shape, pitch is the same.
https://www.digikey.com/en/products/detail/orient-display/afy480272a0-4-3inth/22531855
 

Offline aliarifat794

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Re: 24-bit RGB LDC screen capture?
« Reply #1 on: May 22, 2024, 11:13:54 am »
One possible approach is to use an FPGA-based solution that converts the RGB signals to HDMI. You can consider Terasic DE10-Nano for this purpose.
 

Offline NiHaoMike

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Re: 24-bit RGB LDC screen capture?
« Reply #2 on: May 22, 2024, 01:53:24 pm »
What sort of bitrate are you dealing with? A Cypress FX3 might work.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline coromonadalix

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Offline ajb

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Re: 24-bit RGB LDC screen capture?
« Reply #4 on: May 22, 2024, 02:16:38 pm »
Do you need to capture video, or just stills?  If you have control over the device software, what about dumping the frame buffer to a PC?  A basic USB-UART bridge can do 2-3Mbps, so about 1s to transfer an uncompressed image, wouldn't be too bad for stills.  Something like an FT2232H in FIFO mode can do up to 320Mbps, at your resolution you could do 100fps video over that  :P.
 

Offline Scrts

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Re: 24-bit RGB LDC screen capture?
« Reply #5 on: May 22, 2024, 04:18:40 pm »
Idea 1:
Would be to convert the RGB data to some other format like HDMI and use a capture card to record the display data.

It's RGB data as parallel bus? TFP410 would work then.
 

Offline Sudo_apt-get_install_yumTopic starter

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Re: 24-bit RGB LDC screen capture?
« Reply #6 on: May 23, 2024, 06:11:22 am »
Do you need to capture video, or just stills?  If you have control over the device software, what about dumping the frame buffer to a PC?  A basic USB-UART bridge can do 2-3Mbps, so about 1s to transfer an uncompressed image, wouldn't be too bad for stills.  Something like an FT2232H in FIFO mode can do up to 320Mbps, at your resolution you could do 100fps video over that  :P.

I've thought of this approach, there are no technical limitations but i don't want to create and maintain two separate firmware versions simply for capturing the screen. In my mind the best approach is to capture the data going to the screen, would make things easier down the line :)

Idea 1:
Would be to convert the RGB data to some other format like HDMI and use a capture card to record the display data.

It's RGB data as parallel bus? TFP410 would work then.

This seems like the type of device im looking for. It is a bit unclear with all the sales mumbo jumbo.
This does convert a 24-bit RGB input to a DVI output right?

Thanks for the help everybody, it's much appreciated!




 


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