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Thread: Teensy 3.2 LED spazzing

  1. #1
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    Teensy 3.2 LED spazzing

    Hi all,

    Finally got my Teensy 3.2 working with around 1000 NeoPixel LEDs. I am using the NeoPixel library, and I can change the colors of the LEDs with ease. However, when I try to continuously change the color (i.e. increasing brightness from 0 to 255), the LEDs flicker until it settles at full brightness. Has anyone else encountered this issue? If so, what was the fix? Thanks in advance!
    Last edited by The; 05-24-2017 at 07:54 PM.

  2. #2
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    What rate are you updating the leds with the new color values? My guess is you are updating before finishing writing last update.

  3. #3
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    I am updating them every 4ms. They are also flickering to other colors, so it's not just blue (which is should be).

  4. #4
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    How do you have the Teensy connected to the LEDs? Are you using a 3.3->5V level shifter?

  5. #5
    Senior Member+ MichaelMeissner's Avatar
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    It sounds like your level shifter is not up to the task. Or you are seeing voltage drops on the line.

    In terms of level shifter, the normal level shifters designed for bi-directional i2c/spi lines are just too slow for WS2812B leds. Here is an old article that explored the problem:


    This is the level shifter that is recommended by Paul and others:


    Adafruit wrote this uberguide on best practices of WS2812B LEDs:


    The uberguide does not list it, but if you are doing a large strand, you probably want to run thick power wires back to your power source, and power every n sections. You will need to keep a common ground between all of the lights, but at say every 288 LEDs (assuming you are using 144 LED strips) don't join the power lines and run a separate power/ground back to your power supply.

    Finally, when you are dealing with 1,000 LEDs, you are getting into the domain where you want to use the Octows28111 board and library. This is a board that Paul designed for the Teensy, and it uses all of the advanced features of the Teensy 3.2 and does lights in 8 parallel strands (and hence 1/8th the time to send out the light information).


    And of course verify that your power source really can provide enough power.

  6. #6
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    Thank you everyone for the responses! I am powering my LED strips using a 5V power supply for every two strips (288 LEDs). For ground, should I have the ground wire of the power supplies run back to the common ground as well? It did try adding some of the power supplies to the common ground yesterday and it seemed to improve performance. I will definitely look into Octows28111. Thank you for the tips!

  7. #7
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    Quote Originally Posted by The View Post
    For ground, should I have the ground wire of the power supplies run back to the common ground as well?
    Yes, all grounds need to be connected together.

    [edit - fixed quote]
    Last edited by potatotron; 05-26-2017 at 04:41 PM.

  8. #8
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    Thank you!

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