Unusual LED Behaviour

  • Having run through and set up Hyperion I managed to get it running for about an hour, after much trial and error. Unfortunately after unplugging the strip to re-locate it, it no longer works. Occasionally I'll have the first LED green, if I unplug and plug in the data line it will sometimes change to white or have 1-4 LED's light up, and it alternates between these or different colours.

    I am getting a consistent 5.4V along the entire strip, with 70 Ohms of resistance across each LED. After removing about 1/3 of the strip 1 LED at a time, to test if I had killed the 1st LED, I would occasionally get a lower resistance across the first. Very occasionally would it have an open circuit.

    After having it up and running for an hour I find it hard to think I'm killing the strip with 5.4V, but I get the impression I might be killing the data line. I've done some digging and read I might have to install a resistor from the GPIO pin to the data line, is this necessary? Willing to provide logs, although I'm unable to see anything unusual.

    Any help would be greatly appreciated.

  • 5.4 volts is too much, re-alter PSU to 4.9 / 5 volts under load.

    A resistor directly connected between GPIO and first led can prevent burnt leds ( to high currents)

    If I can make a suggestion, to power the ledstrip from beginning and end will prevent this.

    So +5 volts and GND

    Or you look at my topic where i explain

  • Unfortunately I'm using the not so great "power brick" to run the LED's, so lowering the output voltage is a no go. For now.

    I'm always managing to have the 1st to 4th LED light up, with no voltage change along any of the LED's. Although I am occasionally seeing differing resistance along the Data line, sometimes showing an open circuit. Should I be seeing a change in voltage if I'm killing them through over voltage? Using a multimeter it appears I'm only damaging the data line.

  • What‘s a power brick?

    its a black power brick like the same as your laptop, outcoming is only DC on a jack and you can't alternate the powerline lower or higher.

    most of the times these bricks sucks for the use of small sensible electronics. ;)

    sometimes even this type of PSU will have a "rimple" over DC, if you measure AC over it and you have a result...... :O

    delicate DC electronics really hate AC rimples.

  • you can't kill them by measuring parallel voltage with a GOOD quality multimeter.

    Data line you can't measure with a multimeter, only with scope.

    it will maximum put out aprox 3.3 volts between GPIO and GND.

    So I managed to run or and grab a proper power supply. Steady 5V from start to end.

    Now I'm running into this issue which I've seen posted before.


    I'm beginning to think is either an odd software issue, or I've fried the strip. Is there an easy way to test if the strip is dead?

  • did you correct start the dataline with arrow outwards? like this

    PI > dataline GPIO > ----------------> arrow direction on dataline ledstrip

    did you do ledlayout correct? it seems like the only thing you are providing to the strip is power/GND and no dataline

    what is your setup?

    like OS/ ledstrip type/ledcontroller used/settings Hyperion.NG etc

    in Hyperion is the ledcontroller section running? you can see that in Remote tab.

    and provide a Debug log while you are at it

  • The data line is correct, as I had it working briefly (Follow white cable from back of Pi), including an ad-hoc 470ohm resistor.

    Ws2812b's, running Hyperion.NG as a package from raspbian using the correct controller type.

    LED layout has changed due to cutting the strip during problem solving, which lends me to believe software issue.

    I'll try a fresh reinstall and get back to you with a debug.

  • I did notice in the list that it states:

    Device disabled, device 'ws281x' signals error: 'Failed to open. Error message: Selected GPIO not possible'

    Is there a reason GPIO 19 not being a valid output?

  • GPIO 19 is not for PWM, its for whole other things

    for PWM you can use GPIO 12/13 or 18

    see this schematics >> https://pinout.xyz/pinout/pwm

    you can mouse over and see the function what the GPIO has or can have.

    If you want to run PWM0 then you have to disable audio

    in config.txt


    and you have to make sure Hyperion runs under root and not PI

    You need to run hyperion as root with this configuration (device 'ws281x) PWM

    sudo nano /etc/systemd/system/hyperiond@.service

    Remove the User sessionline and save with CTRL+O and exit CTRL+x.

    Don't forget to reboot

    for SPI you can use SPI0 which is GPIO10

    and make sure in config.txt


    still not working?? read under the line


    most of the guys here prefer the PWM function in ledcontroller and GPIO and not SPI, but you can try both of them.

    in terminal of raspi;

    sudo systemctl disable --now hyperiond@pi

    sudo systemctl enable --now hyperiond@root

    sudo reboot now

    copy and paste this code line with ctrl/shift +V in terminal then press enter

    until last line of reboot

    after reboot

    sudo apt-get update

    sudo apt-get upgrade

    then open hyperion and post debug log

  • and.... if using SPI controller >> the only GPIO that works is SPI0 MOSI or SPI1 MOSI the O in MOSI stands for output

    MISO GPIO is an input, you dont use that one for ledstrips.

    SPI SCLK GPIO you use for 4-line ledstrips

    SPI CE connections is not used.

    just saying.

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