Neo Pixel Strip (30/m), connections

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sleepybrett
 
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Neo Pixel Strip (30/m), connections

Post by sleepybrett »

I've got some recent 30 Pixel per Meter Neopixel strip that I need to split into 8 17 pixel strips and connect them to each other with about 5-6 inches of wire.

On the bench my first strip lights up fine but connecting the second strip (with 24 gauge wire) produces nothing but the briefest flash (albeit with the right colors) when I apply power ( your 5v 10amp supply ).

I'm thinking possibly a timing issue. I tried two separate strips to try to isolate for a dead pixel 1 on strip 2. The code I'm using is very simple currently and should light both strips.

If it is a timing issue I assume I'd have to run each strip off a different Arduino pin, or perhaps if I could duplicate content multiple strips from a single pin?

Thanks!

Sketch code, just for completeness ( I ported rainbowparty up from the older strip, but the red fill also fails to light the second strip ):

Code: Select all

#include <Adafruit_NeoPixel.h>

#define PIN 6
#define LED 13

Adafruit_NeoPixel strip = Adafruit_NeoPixel(34, PIN);

void setup()
{
  strip.begin();
  strip.show();
}

void loop() {
  rainbowParty(120);
  //allRed();
}

void allRed() {
  uint8_t i;
  
  for (i=0; i < strip.numPixels(); i++)
  {
    strip.setPixelColor(i,255,0,0);
  }
  strip.show();
}

void rainbowParty(uint8_t wait) {
  uint8_t i, j;

  for (i=0; i< strip.numPixels(); i+=6) {
    // initialize strip with 'rainbow' of colors
    strip.setPixelColor(i, 255,0,0); //RED
    strip.setPixelColor(i+1, 255,255,0); //YELLOW
    strip.setPixelColor(i+2, 0,255,0); //GREEN
    strip.setPixelColor(i+3, 0,255,255); //TEAL
    strip.setPixelColor(i+4, 0,0,2555); //BLUE
    strip.setPixelColor(i+5, 255,0,255); //VIOLET
 
  }
  strip.show();   
  
  for (j=0; j < strip.numPixels(); j++) {

    // now set every LED to the *next* LED color (cycling)
    uint32_t savedcolor = strip.getPixelColor(0);
    for (i=1; i < strip.numPixels(); i++) {
      strip.setPixelColor(i-1, strip.getPixelColor(i));  // move the color back one.
    }
    // cycle the first LED back to the last one
    strip.setPixelColor(strip.numPixels()-1, savedcolor);
    strip.show();
    delay(wait);
  }
}

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adafruit_support_bill
 
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Re: Neo Pixel Strip (30/m), connections

Post by adafruit_support_bill »

5-6 inches should not be a problem. We usually don't see problems with interconnects shorter than a few feet. Are you sure you are wiring to the input end of the second strip?

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

All the arrows point downstream. I'll grab a photograph when I get back down to the workshop, though there is very little to see ;)

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

Here are those photos:

First the whole shebang:
Image

First the 'send' end:
Image

.. and the 'receive' end:
Image

Further data.

Bridging +5v and Gnd 'downstream' on the second strip gives me a 5.1 reading, as expected.

Bridging DOUT and grnd on the end of strip 1 gives me a variable voltage reading between like 0.00 and 0.02V and on the 'front' of strip 2 the same (at the pad) further down the strip it gives me 0.

Bridging DOUT at s2p0 and DIN s2p1 gives me nothing (but it's pretty unscientific i just took a length of jumper and touched both.

Any other readings I should take to test?

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adafruit_support_bill
 
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Re: Neo Pixel Strip (30/m), connections

Post by adafruit_support_bill »

The solder joints on the output end of the first strip look like cold joints. You should retouch those: http://learn.adafruit.com/adafruit-guid ... n-problems

Since you are getting 5v on the 2nd strip voltage rails, you might try manually running a jumper the DOUT to DIN. Maybe try it a few places along the strip to see if any of the other pixels will respond.

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

So I've forged ahead and soldered the connections onto all 8 strips (upstream), then I went ahead and tested them using a screwdown barrel connector.

4 of 4 exhibit the same 'flash but then do nothing' behavior. I'm not a bad hand with a soldering iron generally and most of the joints on some of the 'bad' strips took nearly perfect. I've never had a problem in a past with any kit or even the older types of strips. Are these neopixels really *that* picky?

What else can I check?

What could I do that would cause the first pixel to blow? Is there a way I could be bridging +5v and data? I'm still seeing Pixel 0 flash on powerup, so it's still at least partially alive.

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pburgess
 
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Re: Neo Pixel Strip (30/m), connections

Post by pburgess »

Could you try something in the constructor call? Do it like this:

Code: Select all

Adafruit_NeoPixel strip = Adafruit_NeoPixel(34, PIN, NEO_GRB + NEO_KHZ800);
It should be doing this automatically when the last parameter is left off, but I encountered strangeness on a project recently...please let me know if it makes any difference.

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

Why would that effect only half the strips (all identical in length)?

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

I think I've come to the conclusion that i've fried half these strips, and I'm trying to figure out what the damage is. It's odd though because my fluke meter has a min/max setting and I'm only seeing a max of 5.262V off the power supply when I test it directly.

I hadn't seen your warnings to use a large cap to absorb the voltage spike off the power supply, I've since added one from my bin, but I'm not sure it's appropriate. It's a 470uf 35V cap. With that cap in place I don't see any 'flashing' when I plug in the strip.

If it is appropriate what kind of damage am I looking at the power rails of course seem fine I've tried a jumper (just touching not soldering) down the strip to no effect (is there perhaps a coating on the pads that I need to burn away?) I'm just going to assume that when I plugged these stips in the voltage jump was too high and all the pixel drivers got wacked. Is there any other way to confirm that ( resistance between the pixel pads? )

I'm hesitant now to plug in the four that were working fine.

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pburgess
 
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Re: Neo Pixel Strip (30/m), connections

Post by pburgess »

It's pretty rare to pop a whole strip, but the first one in the chain can go pretty easily if mis-handled.

If connecting to a live power source, always always connect the GND pin before anything else. Otherwise it seems that power may sometimes follow a destructive route. (Or simply make all the connections first, before powering up.)

Jumpering along the strip should work...with the possible exception if the first fried pixel is actually outputting zaniness down the line and interfering. I'd suggest starting with one of the bad sections of strip, removed from anything else in the chain so you're just working with that section in isolation. Connect ground, 5V and signal (running strandtest on the Arduino or whatever). If nothing happens, try jumpering signal across the first pixel to the second, then third. If still nothing, cut off the first pixel and repeat the process.

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

well it's a barrel connector, one would hope that the ground would connect first (center positive) but *shrug*. I'll try removing a pixel and see what's up. However I did disconnect the wire soldered to the signal pin first before jumpering deeper.

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

I'm still having a lot of difficulty with this product. It just seems so much less stable than 'traditional' led strip. I've now got a strip that lights up but refuses to animate. A strip that was working fine that is now not working. It's really driving me up a wall.

I'm at a loss as to why, after repeatedly asking you can't give me any troubleshooting tips other than 'cut off a pixel and try again'?

On the arduino side I have an uno, signal wire to 6, code above. Adafruit 10A 5V psu, cap mentioned above. PSU ground to ground on the strip, ground jumpered to ground on the uno and 5v from the psu to 5v on the strip. Separate PS to the arduino (5V 2A). I generally plug the main strip power in first and then power up the arduino.

sleepybrett
 
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Re: Neo Pixel Strip (30/m), connections

Post by sleepybrett »

So still nothing from the support team other than 'cut a pixel off and see what happens' .. short answer, nothing. nothing happens.

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pburgess
 
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Re: Neo Pixel Strip (30/m), connections

Post by pburgess »

We're still trying to establish why these pixels are 'popping' for a few customers and not others. A common element has not been identified. Especially as you've got the cap on there, that's the most important thing.

A couple other things I can suggest:
- If connecting to a live power supply, always connect ground first. If 5V and DIN are connected first, it appears the 5V may take an opportunistic path and cook the first pixel. Better just to not connect when power's live.
- Try using a single power supply for the LEDs and the Arduino. Compared to the rest of the strip, the Arduino's using just a flea fart's worth of power...you can hang it off the strip with no problem. (Oh, which reminds me: you mentioned a 5V 2A supply to the Arduino...are you using the barrel jack connector on the board, or using an adaptor to connect wires to the 5V & GND pins on the Arduino?)
- Something I've seen mentioned recently is using a 150 to 300 Ohm resistor between the Arduino data pin and DIN. But I suspect this is more about controlling signal reflections on the line than popping any pixels. Still, might be worth a shot.
- Serious question: what's the weather like there? Wondering if static might be a contributing factor.

I apologize for the frustrations you're experiencing with the NeoPixel strips. This is not typical of the product. I'm sure we can arrange for a replacement (let's try to find the gremlin first) or a refund if you're simply through with it.

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