With or without a resistor?

  • Hi there,


    I have one question about wiring in 3-wire PWM WS2812B from wiki. There is that some people put a resistor 100 Ohm between LED data and Pi GPIO 18. I tried both cases with and without resistor but I don't see any difference.
    1.)Could you please explain me the purpose of resistor in this wiring diagram?
    2.) If I don't see any difference with and without it, is it better to use resistor or not?
    3.) What does it mean "less ringing" in the wiki?


    Many thanks for your patience with my newbie questions :)

  • 1) see 3)
    2) I'm lazy so is leave it how t is now !
    3) dining is a bit like waves bouncing off the side of a pool. This happen with high frequency signals in some depenindkng on lots of things.
    - the signal is sent from the Pi
    - travels along the wiring at about 1/3 the speed of light
    - is reflected by the 1st ws2812
    - travels back along the wire to the Pi
    - is reflected by the Pi and added to whatever the Pi is now sending
    - possibly causing corruption


    If your swimming pool had rubber sides, you'd have much weaker waves bouncing off the walls.


    The resistor is the rubber pool wall

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