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Thread: OctoWS2811 Teensy 3.1 Flickers madly, Teensy 3.0 doesn't.

  1. #1
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    OctoWS2811 Teensy 3.1 Flickers madly, Teensy 3.0 doesn't.

    It has been a long road dealing with flickering LEDS. The same exact setup flickers madly with a Teensy 3.1, but runs smoothly with the Teensy 3.0.

    I got my project to a good state and dealt with the power issues with filter caps close to the strips, adequate power supply & thick enough wire distributing power. Power levels measure well on the multi-meter and oscilloscope.

    I let the smoke out of my original Teensy 3.0 several months ago by accident.
    By this time Teensy 3.1 was out. I ordered a Teensy 3.1 and an OctoWS2811 adapter board. My custom boards worked fine, but I liked the compactness of the ethernet & the twisted pair connections limiting any noise and trusted the produced boards more than my soldering skills.

    I ran into a significant flicker with the Teensy 3.1 that wasn't there with my Teensy 3.0. Since I fried my original 3.0 I didn't have the ability to test it. I ended up ordering a second Teensy 3.1 and a second OctoWS2811 board just to make sure. They both had the same issue. When I recently ordered a Teensy 3.0 and uploaded the same exact sketch, it ran smoothly.

    This is what my Project looks like with the Teensy 3.0 with the stock PlasmaAnimation example
    https://www.youtube.com/watch?v=nW4s1taxhrg

    This is what it looks like with the Teensy 3.1 with the stock PlasmaAnimation example
    https://www.youtube.com/watch?v=3jkspH_u5HA

    I'm going to do more testing, but the jitter in the data-line is way more with the Teesny 3.1 than the 3.0 or the NeoPixel library running on an Arduino Uno.

    Looking at the jitter on the oscilloscope I suspected that maybe an interrupt priority is off or something. You'll see in the video that there is a downstream effect that pixels later in the chain have more issues than than those early in the chain.

    The variance on the data line exists even on the breadboard not hooked up to any of the LEDs. I noted that if I put a
    Code:
    delayMicroseconds(3600)
    after the
    Code:
    leds.show()
    the flicker and jitter is considerably less but still present.

    Details:
    60A Power supply

    16x 1m WS2812B strips with IP65 coating at 60px per meter.
    120pixels per OctoWS2811 channel.
    power connected at the base of each of the 60px strips.
    Filter caps on the strips on +5 and GND at the first pixel of each strand.

    This issue has persisted through many Teensyduino updates and is still present with Teensyduino 1.20 rc3.

    64bit Linux
    Arduino 1.0.5 and Arduino 1.0.6

    $java -version
    java version "1.7.0_65"

    I'd like to use the Teensy 3.1s that I have but need some help getting to the bottom of this issue.

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Maybe you have a very old copy of OctoWS2811 sitting in your sketchbook folder?

  3. #3
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    Quote Originally Posted by PaulStoffregen View Post
    Maybe you have a very old copy of OctoWS2811 sitting in your sketchbook folder?
    There aren't any other copies of OctoWS2811 in my ~/sketchbook/

    $ locate OctoWS2811.h
    /home/<username>/Downloads/OctoWS2811/OctoWS2811.h
    /home/<username>/apps/arduino-1.0.5/libraries/OctoWS2811/OctoWS2811.h
    /home/<username>/apps/arduino-1.0.5-linux64/libraries/OctoWS2811/OctoWS2811.h
    /home/<username>/apps/arduino-1.0.5-old/libraries/OctoWS2811/OctoWS2811.h
    /home/<username>/apps/arduino-1.0.6/libraries/OctoWS2811/OctoWS2811.h
    /home/<username>/workspace/OctoWS2811/OctoWS2811.h


    I've also tried using a brand new Ubuntu OS just to be sure a couple weeks ago.

    I just searched through my files and didn't find anything unexpected redeclaring OctoWS2811

    This is my arduino install: https://github.com/ColinHarrington/a...duino-1.20-rc3
    It should be using the latest OctoWS2811 included in 1.20 rc3

    https://github.com/ColinHarrington/a...es/OctoWS2811/

  4. #4
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    FYI, the latest OctoWS2811 included in teensyduino isn't the latest on github:

    This version was included with teensyduino 1.20-rc3
    https://github.com/PaulStoffregen/Oc...d4f3f663b8023b

    I'm still seeing the flicker with the latest OctoWS2811 library from github:
    https://github.com/ColinHarrington/a...testOctoWS2811

  5. #5
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    I've been looking at the waveforms generated by a few different libraries on an Oscilloscope and this is what I have found:
    https://www.youtube.com/watch?v=juHn...MgUdBRK5nxJqHl

    The NeoPixel Library is very tightly timed - this makes sense given that you are only driving one strip.
    https://www.youtube.com/watch?v=juHncOeou84


    The OctoWS2811 library running on the Teensy 3.0 has just a little bit of jitter in the signal with the PlasmaAnimation.
    https://www.youtube.com/watch?v=FGF_5PvYVMM

    The OctoWS2811 library running on the Teeny 3.1 has a bit more jitter in the signal with the PlasmaAnimation.
    https://www.youtube.com/watch?v=pXDK5juorB4

    I had a friend reproduce this on his own last night with a fresh 64bit Ubuntu 14.04 install so there is absolutely no way the library was changed locally.

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