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Thread: MultiWS2811 - Simultaneously Control 128 WS2811/Neopixel LED strips

  1. #1
    Junior Member
    Join Date
    Sep 2015
    Posts
    19

    MultiWS2811 - Simultaneously Control 128 WS2811/Neopixel LED strips

    After having done multiple projects using an increasing number of WS2811-based LEDs, I hit a point where more channels were needed than OctoWS2811 could provide.
    That's why I created a library and an adaptor board for the Teensy 3.6 that allows 128 channels of WS2811-based LEDs to be controlled simultaneously.

    The library is based on OctoWS2811 and uses DMA and FTM timers to control a series of shift register and multiplexer ICs to construct 128 WS2811 data signals.
    This means that like OctoWS2811, there is minimal CPU impact, which allows the CPU to prepare the next frame while the current frame is sent out to the LEDs.

    The board uses 16 74AHCT595 shift registers, to which the data from memory is copied in parallel using DMA transfers.
    32 74AHC157 multiplexers are used to switch the outputs between the data from the shift registers and a temporally aligned PWM signal to construct the constant high and low parts of the WS2811 protocol.
    Also, 2 74AHCT245 buffers are used to buffer the data clock, latch clock and the high low signal for the multiplexers, as I wasn't sure if the outputs on the Teensy are able to drive that many IC's directly (better safe than sorry).

    The maximum amount of LEDs is currently limited to around 42240 by the amount of RAM on the Teensy 3.6.
    The advantage of having 128 channels as opposed to 8 (max that OctoWS2811 allows), is the ability to achieve higher frame rates when using a lot of LEDs. For example; if you want at least 60 Hz, with 8 channels you're limited to 4416 LEDs, with 128 channels you can push it to the limit of 42240 LEDs and still achieve a frame rate of 100 Hz.

    The library can be found here: MultiWS2811
    Some pictures of the board:
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    If anybody is interested in this board, let me know; I still got a couple of unpopulated ones lying around.
    Also, if anyone is interested in more details on how this works, I can try to extend this post with a more technical explanation.
    Last edited by emiel.h; 06-07-2018 at 04:55 PM.

  2. #2
    Yes Please more technical information.
    Schematic?
    GeckospotNixie

  3. #3
    Junior Member
    Join Date
    Sep 2015
    Posts
    19
    The schematic can now be found here.
    I'll soon make some pictures with the oscilloscope and explain it in more detail.

  4. #4
    Thank you
    Looking Forward to next post.
    GeckospotNixie

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