Arduino Uno/Mega + WS2812B = random flicker/flash

Other Hardware LEDs and Multiplexing
1

Hi guys!

I've been searching all day for a solution to my problem and I'm now desperate enough to kindly ask you guys what I'm missing here.

I bought some sticks with 8 WS2812B leds on them. Not from adafruit, but another company.

However I hooked one of them up to a 5V 10A power supply (which actually supplies 5,3V btw) using a 1000µF cap which bridges between the positive output and ground.
Next was a 470Ohm resistor on the data line running from the Arduino Uno/Mega (tried both) to the actual LED stick.

Then I loaded several example programs which come with Adafruit's NeoPixel library and a few of the FastLED-lib's examples but the output stays the same.
A few LED's are changing color all the time whereas others flicker and flash randomly with no pattern at all. Then it settles back to the actual sketch I loaded and a few moments later the first LED ignores every brightness setting and shines to its fullest.
Just a few examples of what is going on when the LEDs are connected :frowning:

However as of now two of the three sticks I tried won't turn on anymore.
I tried hooking them up to a LiPo with 3,7V which didn't change anything.

Was reading that I maybe would need a level shifter when using voltage below 3,7V to increase the strenght of the actual data signal.

I found a video on reddit where a guy had exactly the same problem and uploaded it to youtube: ws2812b / arduino issue - YouTube

What exactly am I doing wrong? I read many times that the WS2812B are kinda sensitive but I don't want to wait for a specific moon phase for them to actually work properly and reliably... :slight_smile:

Do you guys have any suggestions of what I could be doing wrong?!

Cheers and thank you ever so much!
Mario

2

Did you connect the grounds?

The guy in the video made the mistake of trying to use a 470K instead of 470R.

3

PaulRB:
Did you connect the grounds?

The behaviour described absolutely sounds as if he did not.

4

PaulRB:
Did you connect the grounds?

The guy in the video made the mistake of trying to use a 470K instead of 470R.

Paul__B:
The behaviour described absolutely sounds as if he did not.

I didn't. Now it works and I feel stupid!
Guys thank you so much!!!

Can you tell why the first sticks won't turn on anymore?! Did I blow up something?!

5

Not sure. Failing to connect the grounds should not, by itself, have damaged anything. Getting the power and/or data connections wrong might have done... or maybe they are just poor quality. Maybe you made some dry joints, or broke a pcb track by bending?

6

Failing to connect the grounds should not, by itself, have damaged anything.

Yes it could. It means that the signal level when a zero tries to parasitically power the chip.

It is likely that only the first LED in the strip is blown, these chips are not very robust against abuse.

7

Grumpy_Mike:
Yes it could. It means that the signal level when a zero tries to parasitically power the chip.

Fair enough, I stand corrected.