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Thread: Teensy 3.2 Octows2811 fastled flickering problem

  1. #1
    Junior Member
    Join Date
    Feb 2016

    Teensy 3.2 Octows2811 fastled flickering problem

    Hi - I am having a flickering problem with the fastled library. I am using Teensy 3.2 and fastled 3.1.6.

    I'm not doing anything complicated - just getting the hardware set up and tested. The teensy is connected to a 5m, 12v, 100 pixel WS2811 strip through a 74HCT245 (Vcc at 5v) and a 100ohm resistor. I am using the DemoReel100 from the fastled examples folder, using pin 2 as the output pin. The strip flickers dramatically regardless of brightness level.

    I have tried decreasing the clock speed of the teensy from 96 Mhz to 48 and 72Mhz without any difference.

    I have also added the line: #define FASTLED_ALLOW_INTERRUPTS 0, but that doesn't help either.

    When I run the "rainbow" example from the octows2811 example folder - without any change in hardware - the rainbow works perfectly with no flickering. So, I know that the hardware is connected correctly.

    Any ideas?

  2. #2
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    I have the OctoWS2811 test board right here, 240 LEDs per pin.

    If you post the code, I'll copy & paste into Arduino and run it here on the known-good test hardware. Should be easy to see what it does on the first 100 LEDs. But I don't have a lot of time for guesswork, so please post the exact code I should copy & paste into Arduino.

  3. #3
    Junior Member
    Join Date
    Feb 2016
    Hi Paul!

    Here is the code for the DemoReel100. The Octows2811 library seems to be working fine. I would use it, but I need to do 12 strips in parallel. The only thing I added to this example is "#define FASTLED_ALLOW_INTERRUPTS 0
    ", which didn't make any difference

    #include "FastLED.h"
    // FastLED "100-lines-of-code" demo reel, showing just a few 
    // of the kinds of animation patterns you can quickly and easily 
    // compose using FastLED.  
    // This example also shows one easy way to define multiple 
    // animations patterns and have them automatically rotate.
    // -Mark Kriegsman, December 2014
    #if defined(FASTLED_VERSION) && (FASTLED_VERSION < 3001000)
    #warning "Requires FastLED 3.1 or later; check github for latest code."
    #define DATA_PIN    2
    //#define CLK_PIN   4
    #define LED_TYPE    WS2811
    #define COLOR_ORDER RGB
    #define NUM_LEDS    100
    CRGB leds[NUM_LEDS];
    #define BRIGHTNESS          255
    #define FRAMES_PER_SECOND  120
    void setup() {
      delay(3000); // 3 second delay for recovery
      // tell FastLED about the LED strip configuration
      FastLED.addLeds<LED_TYPE,DATA_PIN,COLOR_ORDER>(leds, NUM_LEDS).setCorrection(TypicalLEDStrip);
      //FastLED.addLeds<LED_TYPE,DATA_PIN,CLK_PIN,COLOR_ORDER>(leds, NUM_LEDS).setCorrection(TypicalLEDStrip);
      // set master brightness control
    // List of patterns to cycle through.  Each is defined as a separate function below.
    typedef void (*SimplePatternList[])();
    SimplePatternList gPatterns = { rainbow, rainbowWithGlitter, confetti, sinelon, juggle, bpm };
    uint8_t gCurrentPatternNumber = 0; // Index number of which pattern is current
    uint8_t gHue = 0; // rotating "base color" used by many of the patterns
    void loop()
      // Call the current pattern function once, updating the 'leds' array
      // send the 'leds' array out to the actual LED strip;  
      // insert a delay to keep the framerate modest
      // do some periodic updates
      EVERY_N_MILLISECONDS( 20 ) { gHue++; } // slowly cycle the "base color" through the rainbow
      EVERY_N_SECONDS( 10 ) { nextPattern(); } // change patterns periodically
    #define ARRAY_SIZE(A) (sizeof(A) / sizeof((A)[0]))
    void nextPattern()
      // add one to the current pattern number, and wrap around at the end
      gCurrentPatternNumber = (gCurrentPatternNumber + 1) % ARRAY_SIZE( gPatterns);
    void rainbow() 
      // FastLED's built-in rainbow generator
      fill_rainbow( leds, NUM_LEDS, gHue, 7);
    void rainbowWithGlitter() 
      // built-in FastLED rainbow, plus some random sparkly glitter
    void addGlitter( fract8 chanceOfGlitter) 
      if( random8() < chanceOfGlitter) {
        leds[ random16(NUM_LEDS) ] += CRGB::White;
    void confetti() 
      // random colored speckles that blink in and fade smoothly
      fadeToBlackBy( leds, NUM_LEDS, 10);
      int pos = random16(NUM_LEDS);
      leds[pos] += CHSV( gHue + random8(64), 200, 255);
    void sinelon()
      // a colored dot sweeping back and forth, with fading trails
      fadeToBlackBy( leds, NUM_LEDS, 20);
      int pos = beatsin16(13,0,NUM_LEDS);
      leds[pos] += CHSV( gHue, 255, 192);
    void bpm()
      // colored stripes pulsing at a defined Beats-Per-Minute (BPM)
      uint8_t BeatsPerMinute = 62;
      CRGBPalette16 palette = PartyColors_p;
      uint8_t beat = beatsin8( BeatsPerMinute, 64, 255);
      for( int i = 0; i < NUM_LEDS; i++) { //9948
        leds[i] = ColorFromPalette(palette, gHue+(i*2), beat-gHue+(i*10));
    void juggle() {
      // eight colored dots, weaving in and out of sync with each other
      fadeToBlackBy( leds, NUM_LEDS, 20);
      byte dothue = 0;
      for( int i = 0; i < 8; i++) {
        leds[beatsin16(i+7,0,NUM_LEDS)] |= CHSV(dothue, 200, 255);
        dothue += 32;

  4. #4
    Junior Member
    Join Date
    Feb 2016
    Hi again - Switching from LED_TYPE WS2811 to WS2812 appears to have resolved this problem.

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