frame buffer help

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hydronics
Posts: 4
Joined: April 27th, 2018, 7:33 pm

frame buffer help

Post by hydronics » May 1st, 2018, 1:59 pm

Hello! I need help creating the frame buffer from the decoded HDMI values and then reordering those bytes into the correct LED strips.

I am successfully bringing in HDMI data and decoding it into X,Y,R,G,B vales. I'd like to set that into a frame buffer and then write portions of the frame buffer to LED strips over SPI.

I started some basic starter libraries... one for driving APA102 LED strips and one for decoding HDMI signals.
https://github.com/hydronics2/mojo_fpga

Any help or direction? thanks!

embmicro
Site Admin
Posts: 834
Joined: March 24th, 2013, 12:45 pm

Re: frame buffer help

Post by embmicro » May 9th, 2018, 11:50 am

I'm assuming you're trying to make some RGB LEDs controllable over HDMI. How to do this really depends on how many LEDs you have.

If you don't have THAT many you can probably get everything to fit nicely in the FPGA's internal RAM. Simply make a block ram with enough space to store the colors of each LED. I wouldn't try to save the entire HDMI frame as it'll just waste a bunch of resources. Only save the pixels you are actually using.

You will also probably want to bridge the HDMI decoder clock domain to one based on the 50MHz crystal on the Mojo using an asynchronous FIFO (in the components library).

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