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Topic: WS2811 driving (supposed) 5050RGB will only light up red (Read 949 times) previous topic - next topic

Stov

Hi there. A while back I ordered a couple of these strips: http://www.ebay.com.au/itm/152266299098

I recently received my new 5V 40A power supply to drive these and was doing some preliminary testing tonight.

Unfortunately, using both FastLED and the Adafruit Neopixel library I can only get the LEDs to light up red. Attempting green or blue just leaves them off. For example, the Neopixel "strand test" example sketch runs through just fine but only with the red "channel".

Now, some thoughts on what may be going wrong:

- These strips actually need 12V DC instead of 5V (i.e. title of the listing was incorrect about input power) and given red has the lowest voltage requirement it's the only one that CAN light up. I do have two strips and technically only need one so I can try to track down a 12V power supply to do some basic testing, potentially blowing out one of the strips. The strip itself does have "12V" on the +V line (see last image in listing)
- Both the strips are busted in exactly the same way (seems unlikely)
- I actually got sold 5050 red LEDs, not RGB

I'm just looking for some insight from those more experienced with these things before I damage anything and/or for tips on further troubleshooting. I've attached a photo of how everything is wired together, it's pretty simple. That's a 220 ohm resistor plugged into the breadboard.

Much appreciated.

Stov

After some more quick testing it looks like the "individually addressable" portion of the title is also a bit of a lie. Looks like only three LEDs at a time can be addressed. This code:

  strip.setPixelColor(0, strip.Color(255,0,0));
  strip.show();
  strip.setPixelColor(1, strip.Color(255,0,0));
  strip.show();

will light up the first six LEDs.

Grumpy_Mike

Yes that is right it is what those strips do.

You need to power them with 12V and 5V. The 12V is the LED power supply and provides the current to light up the LEDs. The 5V supplies power to drive the WS2811 control chip. Each chip controls three series LEDs for each colour. There is an example of the circuit it uses in the WS2811 data sheet.

As you said if you only supply 5V to the 12V supply there is not enough voltage to turn on three blue or green LEDs.

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