LED raspberry Pi Software wall help!
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LED raspberry Pi Software wall help!

by winterpeg on Sat Feb 23, 2013 2:57 pm

I have a large number of Ada fruit RGB square LED strings.. I would like like 2 build a Addressable sign matrix 4x8 foot and 4x16.. I also hope 2 use Raspberry PI and PMW16 boars 2 control sign (text and animation)
Have a bench top setup as per projects posted... however have hit a wall with what can do for software 2 address this type of array..
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Re: LED raspberry Pi Software wall help!

by paulstoffregen on Thu Feb 28, 2013 3:02 pm

For a really large LED wall, you're probably going to need to stream the data over USB from the Raspberry Pi to another board (or multiple boards using USB hubs) that can output the data fast enough for so many LEDs. The USB is designed to efficiently move lots of data... and you're going to need the Pi working on processing the video and converting it to LED bitstreams.

I've written 2 of these applications, which work with 2 types of addressable LEDs Adafruit sells.

If you have the LPD8806 strips, you'll probably want to look at this:


Here's a project where that code that used it for a video wall:

http://www.dorkbotpdx.org/blog/armatron ... video_wall

Buried on that page is a link to the source code on github... the code which reads the video and send out the USB port. I believe they used a small form-factor PC and a USB-based video capture device, so it read the video in, converted the data for LEDs, and streamed it right back out another USB cable to the board driving that LED wall.

If you're using NeoPixel, you'll probably want to use my new OctoWS2811 library:

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Re: LED raspberry Pi Software wall help!

by pburgess on Thu Feb 28, 2013 10:58 pm

If you're using the WS2811 square LEDs, the 'ledstream' sketch for Arduino is already written to handle large displays, though for transfer speed I'd recommend a USB-native board like the Teensy 2.0 or Arduino Micro. For the host-side software, download the code for the Adalight project and look at the examples written in Processing (there's a simple C example as well).
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