16 leds Neopixel ring

EL Wire/Tape/Panels, LEDs, pixels and strips, LCDs and TFTs, etc products from Adafruit

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
ftondini
 
Posts: 3
Joined: Fri Mar 21, 2014 1:23 pm

16 leds Neopixel ring

Post by ftondini »

I purchased two Neopixel rings (16 leds).
One of the rings works flawlessly, but the second has a weird behavior: when I address led n.0, led 14 lights too, if I address led n.1, led 15 lights too.
If I address led 14 or led 15 nothing happens.
Leds 0 and 14 seem coupled together and so leds 1 and 15.

User avatar
adafruit_support_mike
 
Posts: 67454
Joined: Thu Feb 11, 2010 2:51 pm

Re: 16 leds Neopixel ring

Post by adafruit_support_mike »

That's definitely unusual. Could you post a photo of the front and back of the ring please?

ftondini
 
Posts: 3
Joined: Fri Mar 21, 2014 1:23 pm

Re: 16 leds Neopixel ring

Post by ftondini »

here are pictures:
Led 0 and 14 light
Led 0 and 14 light
P1100693.JPG (276.49 KiB) Viewed 238 times
Rear view
Rear view
P1100691.JPG (342.19 KiB) Viewed 238 times
Front view
Front view
P1100690.JPG (363.09 KiB) Viewed 238 times
This is the code I used to switch led 0 and 14 (or 1 and 15) on:

#include <Adafruit_NeoPixel.h>

#define PIN 2

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(16, PIN);

//uint32_t color = 0xFF0000; // Start red
void setup() {
pixels.begin();
pixels.setBrightness(20);
// switch on led 0, color pale red
pixels.setPixelColor(0, 0xFF0000);
pixels.show();
}

void loop() {

}

User avatar
adafruit_support_mike
 
Posts: 67454
Joined: Thu Feb 11, 2010 2:51 pm

Re: 16 leds Neopixel ring

Post by adafruit_support_mike »

Check for a solder bridge here:
P1100690.JPG
P1100690.JPG (67.39 KiB) Viewed 229 times
Pixel 0 is actually two spaces clockwise of the IN pad, as shown. We had to backtrack the signals a little to make all the connections work.

The pin closest to the IN pad on pixel 1 is DATA-OUT, which connects to DATA-IN on pixel 2. If a bit of stray solder connected the IN pad to pixel 1's DATA-OUT, the ring would see signals entering at two places. The results would match what you're seeing.

ftondini
 
Posts: 3
Joined: Fri Mar 21, 2014 1:23 pm

Re: 16 leds Neopixel ring

Post by ftondini »

I checked leds contacts and I didn't notice any stray solder, tomorrow I'll try to remove all the solder paste with a desoldering braid.
However some weird behaviors remain.
I thought the pixel 0 was the one you call pixel 2 because:
a) when I switch on pixels 0 two pixels light (now I know be 0 and 2)
b) when I switch on pixels 14 and 15 nothing happens
c) when I switch on pixels 2, 3 to pixel 13, all of them light in the same order starting from the position now I know be 4
so I wrongly guessed that all pixels was shifted toward left by two positions.
A short summary (using correct pixels numbers):
if I switch on pixel 0, pixels 0 and 2 light;
if I switch on pixel 1, pixels 1 and 3 light;
if I switch on pixels 2 to 13, pixels 4 to 15 light
if I switch on pixel 14 or 15, nothing happens.

Is this behavior compatible with false contacts near IN pad?
Thank you for all extremely quick answers.

User avatar
adafruit_support_mike
 
Posts: 67454
Joined: Thu Feb 11, 2010 2:51 pm

Re: 16 leds Neopixel ring

Post by adafruit_support_mike »

That's exactly what I'd expect from a connection between the input line and DIN for pixel #2.

Try getting well-lit macro photos of the front and back of the ring in the area around the DIN pin. If you don't have a solder bridge, there might be a stray connection in the PBC. Those are rare but not impossible, and the black soldermask would make it hard to see one without looking for it specifically.

Locked
Please be positive and constructive with your questions and comments.

Return to “Glowy things (LCD, LED, TFT, EL) purchased at Adafruit”