Hi, I have a question regarding startup behavior of RGB LED strips. I have two kinds of strips, WS2812 based and APA102 based. In my application the strips shall start showing some animations after being powered up. But most of the times the strips do not start with all ‘black’ pixels. I am using an arduino board for controlling. I added a 1s delay after startup to be able to see the effect and in this timeframe some of the pixels are already lit up. If power is only interrupted for a short time the LEDs will light up in the color they had before switching of the power. Is this behavior known and expected? And how can this be avoided?
I would like to add that apart from the described issue the FastLED lib is of course working as a charm. I only post it here because so many experienced users are hanging around here.
@Lars_Haack Do you have a resistor on your data line? I have a similar thing happen with some LEDs lighting up random colors when power is first applied to the strips if a resistor is not used with WS2812. With my APA102 strips this will have if my clock line doesn’t have a good connection to my board.
Thank you very much for your fast answer. I have a resistor in the data line of the WS2812 strip. Also a capacitor between 5V and GND. I will have to check with my APA102 strip if i can improve the clock connection/signal quality.
@Lars_Haack What board are you using to run the strips and have you checked your voltages? I have a pair of shoes that I added LEDs to that fail to work correctly if the voltage is above 4V since the board is 3.3V logic.
Other than that I don’t have any suggestions and would defer to the more experienced people here.
I have seen this problem with APA102. Its annoying as hell. One of my biggest projects to date has 2300 pixels, and i had to build in a staggered power feed system. If i applied power to all the LEDs at once, they would randomly light up no matter what i did! I suspect the more you have strung together the worse the random behavior is. I posted about this previously here https://plus.google.com/102639486677013343669/posts/1d3G9ddZoHL