I have been asked to fill a 12m by 0.4m area with an LED

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I have been asked to fill a 12m by 0.4m area with an LED matrix by a friend. So I have been looking at the Octo DMA library but have just noticed the multi strip additions to FastLED. I am thinking about 24 strips of 720 leds. My question is about what appears to be 2 different systems. I presume OCTOWS2811 uses DMA and that WS2811_PORTD does not, has anybody used these? Is the non DMA’d type much slower than driving a single clockless strip?

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Hi Aaron,

what kind of content will the matrix be displaying?

What sort of refresh rate are you hoping to achieve?

Which pixels are you planning to use?

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Scrolling text, sprite animations and patterns. Was thinking about WS2812’s hence my questions about the Octo stuff. Have previously run 800 off a single wire with a Teensy 3, which just about managed an acceptable refresh rate. But if the multi output works well I could drive all the strips/LEDs off just 2 Synced Teensy’s. I should really just deconstruct one of my Matrixes and hook it up to do some timings, just hoped someone here may have already tried the code out :slight_smile:

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I asked, because I didn’t want to give you a bum steer, if you came back with, “oh great, this video wall will be awesome”.

Have a read of:

https://github.com/FastLED/FastLED/wiki/Parallel-Output

I haven’t tried the OCTO driver yet its sat here looking at me, but looking at the timings on that page 720 LEDs is fine.

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SO, 24 strips * 720 LEDS = 17,280 LEDs.

That means your Teensy3.1 will be running 8 lines of 2,160 LEDs in parallel. With my calculations, it would take 7,992us to write 8 lines.

And, 51,780 bytes of space will be needed for your leds[] array.

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Thanks Stuart Taylor for the RTFM :slight_smile:
First used FastLED a year ago and have got used to scanning the source code for help due to the limited instructions but now I see the guys have made a massive effort to get the documentation updated!
Hi Jon, I am actually thinking about using 3 Teensy 3.1’s so would only drive 8 strings of 720 off each one and would just need to sync the Teensy’s using a single data line. From what I can see the Octo code requires 6 bytes for each LED only (4320) and FastLED is 1 per LED (5760). So only 10K LED RAM per Teensy.
TBH The bit that worries me is the power, 300w 5v supplies I can get at a good price, but will need 24 of them!

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Hi Aaron
I tried all of your example in RGBLEDS, with FastLED 3.1
All of examples have the same error:
Arduino: 1.0.6 (Windows Board: “Arduino Uno”
MatrixExample1:15: error: expected constructor, destructor, or type conversion before ‘<’ token
MatrixExample1:15: error: expected unqualified-id before ‘>’ token
MatrixExample1.ino: In function ‘void setup()’:
MatrixExample1:22: error: ‘leds’ was not declared in this scope
Thanks for help me out.

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Hi,
I use v1.0.5.r2 with Teensyduino addon, I couldn’t find 1.0.6 on the Arduino website.
Having said that it seems to be failing with the template aspect of the Matrix class which is standard ‘C’. I would try reinstalling the Arduino software or even upgrading to V1.5.8 as you are using an Arduino board. Sorry I can’t be more help but I don’t have an Uno only a Due which requires 1.5 and above.

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Thanks
I’ll try 1.0.5r2