Weirdness! I haven’t used NeoPixels since discovering APA102 but I picked up this great 32x32 NeoPixel panel that I wanted to put to use. It tested fine with the Adafruit NeoPixel library, but after switching my code over to FastLED I get this random glitch effect.
I’m running the data line through a 74HCT245 and a 480 Ohm resistor, and I’m using a Teensy 3.6 SPI pin (Pin 11). (The same glitch occurs when bypassing the buffer and resistor.)
This test animation simply moves a pixel along the string of 1024 LEDs. If I change the NUM_LEDS to 256, it moves much faster but exhibits the same glitch problem. I’ve noticed that the glitch always appears before the active LED in the sequence. Any thoughts? https://youtu.be/aTJaY1-j9cU
@Stefan_stelb_Le_Bret Thanks for the suggestion, but I’m not using anything other than the Teensy 3.6.
Also, to be clear, the glitch isn’t exactly a flicker. It moves the entire frame buffer backwards in the strip. The dots you see flickering are supposed to be a part of the consecutive sequence but they’re being rendered on the wrong LED (strip zigzags top to bottom). This is more apparent when displaying full screen animations.
But I just ran one of the examples and it works fine, so there’s a conflict with something else in my code. Odd, because the simple running dot animation above blocks everything else. Maybe an interrupt, but I don’t think I’m using any. I’ll tinker and report back.
@Jeremy_Williams - Thank you for your response. Any chance that they still are making them or do you know of anyone making a large panel like that with APA 102?
Ah - the frame being moved backwards in the strip means that the interrupt allowing code is allowing a bit too much of a time gap when an interrupt occurs. Making this more easily tunable is one of the first things on the list when I get back to working on the library.
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(from AliExpress Android)