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SOLVED Black (dim) values gives "random" light

Discussion in 'Software Support' started by Martijn, 27 December 2016.

  1. Martijn

    Martijn New Member

    Messages:
    4
    Hardware:
    RPi2
    Hi all, I've got two 12 volt WS2811 strips hooked up to a RPi2 via a level converter on GPIO (18). Controll and grabbing works fine, until the light should be dimmed, then it just goes crazy. Best example is when I use the color wheel. Full brightness gives all the right colors, also sliding to white. But when I try to dim the light (even a little bit), some parts of the strips turn another color, fully on. Depending on which color I try to dim, they turn blue or green. And when the light should be completely off, they still give very dimmed red light, with some parts still blue or green. Also when using effects which should have some black parts, the lights stay very dimmed red.

    I think I looked at every configuration that could have influence, but I can't find any. And I think it's a software issue, because full brightness works fine on any color aswell as effects which give full brightness like rainbow swirl and solid police lights.

    On LibreELEC there is one screensaver however that gives correct results with parts of the LED strip turned fully off like it should.

    I added three photo's showing the results. Showing red fully on (no errors), the screen saver with some parts off and some parts on (no errors), red slided to black, but instead shows dimmed red and a part green instead. The other LED strip goes even more berserk with most parts green.

    IMG_20161223_182807.png IMG_20161223_182933.png IMG_20161223_182959.png

    Here is my hyperion configuration:
     
  2. penfold42

    penfold42 Moderator Developer

    Messages:
    595
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    What sort of level shifter do you have ?

    I've found those mosfet "bidirectional" level shifters to be pretty crap.
    A 1k pull-up on the 5v side helps but some setups will never be great.
     
  3. Martijn

    Martijn New Member

    Messages:
    4
    Hardware:
    RPi2
    Guess what level shifter I use... bidirectional mosfet. This is a hardware issue then I guess. I've got the RPi, which gives 3.3v and the LED strips, which are 12v. Should I put the resistor on the RPi side of the level shifter or on the LED strip side? You said 5v side, I'm guessing you assumed I had 5v LED.

    What is a good option to go from 3.3v to 12v?
     
  4. Martijn

    Martijn New Member

    Messages:
    4
    Hardware:
    RPi2
    Found it! I've got 10 meters of LED strip, so I calculated the power supply had to be 6A. It turned out that was too much, replaced it with a 3A and now it works like a charm.
     
  5. penfold42

    penfold42 Moderator Developer

    Messages:
    595
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Sorry I missed your reply in December.

    A proper regulated supply should be fine even if it's current rating exceeds what you need from it.
     
  6. Martijn

    Martijn New Member

    Messages:
    4
    Hardware:
    RPi2
    Strange... When I tried to dim the light, some parts went crazy, lighting up even brighter. Not limited by too much knowledge about addressable LED strips, I guessed the supply was to powerful. If that can't be the cause, than the power supply must have failed in another way. Thanks for your reaction.