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Only First Led Works
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Only First Led Works

by zachtaylor on Tue Sep 10, 2019 10:34 am

Did I smoke my led strip? Only the first light works.

https://imgur.com/a/7vCdBJm

I was following the first diagram here with a 5V 10A power supply on a 4 meter strip. If so, oof and what did I do wrong?

https://learn.adafruit.com/neopixels-on ... -pi-wiring

Code: Select all | TOGGLE FULL SIZE
import time
import board
import neopixel
pixels = neopixel.NeoPixel(board.D18, 240)

pixels.fill((0, 0, 40))


pixel wiring.jpg
pixel wiring.jpg (231.54 KiB) Viewed 120 times

pixel.jpg
pixel.jpg (1003.9 KiB) Viewed 120 times
Last edited by zachtaylor on Tue Sep 10, 2019 11:25 am, edited 1 time in total.

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Re: Only First Led Works

by dastels on Tue Sep 10, 2019 11:21 am

It would help to see your code. Please click the code tage above and paste your code between the inserted tags.

Dave

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Re: Only First Led Works

by zachtaylor on Tue Sep 10, 2019 11:27 am

Good point. This is all new to me, so the issue very well could be the script. Right now it's just a sample script using fill. The first post is updated with the script.

Also, pay no mind to the +- on my board. The one in the wiring diagram is reversed from mine and to keep from screwing things up I treated the connections the same on my breadboard.

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Re: Only First Led Works

by dastels on Tue Sep 10, 2019 12:26 pm

Hmm. The code is fine.

As for the +/- rails. Rotate the breadboard 180 degrees. That happened to me... really messed me up until someone pointed it out.

The next ting I'd do is verify all the wiring. You could try connecting the strip's power and ground directly yo the screw terminals. That's a lot of LEDs, which means lots of power, which need heavy wiring.

Also, in the image the LED looks green, whereas the code is setting it to blue.

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Re: Only First Led Works

by adafruit_support_bill on Tue Sep 10, 2019 12:37 pm

Another thing to check: Make sure that you are connected to the right end of the strip. The arrows on the strip should be pointing away from your connections.

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Re: Only First Led Works

by zachtaylor on Tue Sep 10, 2019 12:47 pm

Rotate the board....doh.

I've played around with RGB values, thus, the discrepancy. Color is matching whatever the script is set for.

I tried direct wiring as shown below. GPIO connections are going in the right direction, but for testing purposes I've tried both ends. I've also powered from both ends. Still just getting the first light.

Also, I just measured the voltage coming out of the power supply, 5 volts.

pixel simplified wiring.JPG
pixel simplified wiring.JPG (156.08 KiB) Viewed 89 times

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Re: Only First Led Works

by zachtaylor on Tue Sep 10, 2019 4:24 pm

I am now noticing that the first pixel won't cycle colors unless it is slightly pinched at the wiring.

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Re: Only First Led Works

by dastels on Tue Sep 10, 2019 5:02 pm

Sounds like a bad connection.

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Re: Only First Led Works

by staticsan on Wed Sep 11, 2019 11:55 pm

Are you signalling at 5V or 3.3V? It should be the same as what you're powering the strip with.

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Re: Only First Led Works

by adafruit_support_bill on Thu Sep 12, 2019 6:07 am

Are you signalling at 5V or 3.3V?

Good point. Looks like you are controlling with a Pi, so the signal level will be 3.3v. The Neopixel spec for the logic HIGH threshold is 0.7*VCC. If you are powering the pixels from 5v, that translates to 3.5v. So a 3.3v signal is not guaranteed to be recognized by the pixels.

The two choices are:
1) use a level shifter such as the 74ACHT125 https://www.adafruit.com/product/1787
2) Power the pixels from a 3.7v LiPo cell or a 3xAA alkaline pack (4.5v)

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Re: Only First Led Works

by zachtaylor on Thu Sep 12, 2019 8:40 am

In my initial wiring this was the configuration. A level shifter was in place. Customer Service set me up for an exchange, but didn't request a return on this one.

I'll probably experiment with this one a bit. Get an Arduino, cut it up, resolder, etc. and see what I can do with it.

led_strips_raspi_NeoPixel_Level_Shifted_bb.png
led_strips_raspi_NeoPixel_Level_Shifted_bb.png (159.51 KiB) Viewed 22 times

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Please be positive and constructive with your questions and comments.