Control led strip WS2812B

Other Hardware LEDs and Multiplexing
1

Hello everyone, I have bought a led strip: WS2812B bur I can't make it work.

Following some online tutorials I have wired it to an Arduino Uno as follows:

Power supply: AC adapter: Output 19V - 6.3 A
The power supply is connected to a buck converter. I brought the voltage down to 5V.

On the LED strip there are 3 connections: -; +5V; Di.
However, there are 5 wires connected:

Img1 Led to buck converter
Image 2 Led to buck converter
Image3 Led to buck converter
Image 4 Led connections

As I saw from the internet (for instance how to connect example) I connected the +5v to the positive side of the 5V buck converter, the ground to the negative side of the buck converter. Then, I connected the green wire (Di) to pin 7 of the Arduino (the yellow wire in my picture). Finally, I have also connected the gnd from the buck converter to the gnd on the Arduino (purple jumper in the picture).

Then, just to try whether this was working, I have downloaded the fastLED library.

Then, I have uploaded this code that I found from internet:

#include <FastLED.h>
#define LED_PIN     7
#define NUM_LEDS    20
CRGB leds[NUM_LEDS];
void setup() {
  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
}
void loop() {
  for (int i = 0; i <= 19; i++) {
    leds[i] = CRGB ( 0, 0, 255);
    FastLED.show();
    delay(40);
  }
  for (int i = 19; i >= 0; i--) {
    leds[i] = CRGB ( 255, 0, 0);
    FastLED.show();
    delay(40);
  }
}

I will try to also add a fritzing scheme, but this should be quite clear I think...

Does anyone have any idea why this is not working?

Thank you in advance for your time and comments.

2

Update:
it works now. I think there was simply a problem with the connectors. There are connectors on both sides of the LED strip. I was trying all possible ways on the connections on one side and it was not working.
Finally, I tried the wires on the other side of the LED strip and immediately worked.
I guess we could even delete this post.
Thank you anyways.

3

You mean to say you were trying to feed data into the "OUT" side of the WS2812 chain instead of into the "IN" side. :roll_eyes:

That is not going to get you anywhere!

4

OH...I see..I thought I read somewhere that they were both the same and it didn't matter which side you used...

5

Gluce:
OH...I see..I thought I read somewhere that they were both the same and it didn't matter which side you used...

That only applies to power not the data signal. Also it is best to supply the power to both ends, to minimise any voltage drop along the strip.

6

Gluce:
OH...I see..I thought I read somewhere that they were both the same and it didn't matter which side you used...

After a WS28112 receives its data, it will re-transmit any further data sent to its IN pin on its OUT pin.
In that sense, IN and OUT will show the same data, but IN is a receive only and OUT is transmit only

7

Grumpy, boolrules, thank you both for your suggestions and info.
I will do as you said.