2

I was trying to follow this project and I fried my Pi, (it started smoking and shut off).

I'm hoping you guys can help me identify why it fried so i don't keep trying things and cooking Pi's.

In this image I have spliced a 5V 10A power supply and soldered it to 2 of the wires on the neopixel strip. Note that brown is hot and blue is ground.

enter image description here

You can see in this image that my brown wire is connected to the power on my breadboard and the blue is connected to the ground on my breadboard.

enter image description here

You can see in this image that there are 4 wires coming out of the neopixel strip - 2 black, 1 red, and 1 white. One of the blacks and the red are what I soldered to the power supply. The other black and the white I haven't done anything with yet.

enter image description here

Is there anything obvious that I did wrong here? Some possibilities that I'm thinking could have caused me to fry my raspberry pi:

  1. I accidentally connected the 5V from the power supply to the 3V3 pin on my raspberry pi instead of the 5V

  2. I have the wrong side of the neopixel strip?

Any other ideas?

  • I think you don't want the brown wire anywhere near your pi. You want both the neopixels blue wire attached to the Pi ground and the Neopixel data line (white?) attached to a GPIO. The Neopixel data line is input (to the Neopixel) only. The Neopixels will draw power from your 10Amp power supply while the Pi will be powered by its own USB input. All that wants to be sent from the Pi to the Neopixels is data and that needs a common ground. – Kolban May 10 '16 at 5:27
  • 1
    What connections have you made from the breadboard to the Pi? – TomG May 10 '16 at 10:58
  • @TomG The orange wire is connected to the MOSI pin and the gray wire is connected to the SCLK pin as in this diagram learn.adafruit.com/assets/13630 – Catfish May 10 '16 at 14:11
  • @Kolban I connected the brown wire to the 3V3 pin on my pi as is shown in this diagram learn.adafruit.com/assets/13630. I wasn't really sure why it shows that power be connected to the power supply as well as the 5V pin on the pi so I did that and poof! – Catfish May 10 '16 at 14:13
  • 1
    @Catfish WAIT! ... I just re-read what you said. You said you connected the brown wire to 3.3V. Isn't the brown wire the output of your power supply? Isn't that 5V!!! The diagram shows that the "brown" wire should be wired to 5V input ... NOT 3.3V. If you had connected to 3.3V ... then yes, your Pi would die horribly. – Kolban May 10 '16 at 15:21
3

The LED strip has two ground cables. It's hinting at building two circuits, as spotted in the comments; a power circuit and a data circuit. These should be kept separate.

Connect the power supply to Red and Black of the LED strip, as you have done. Do make sure to use a DC power supply though. Remove your Raspberry Pi connections from this power circuit.

For the data connection, use the White and Black of the LED strip. The white cable may accept 5V or 3.3V data input and will draw a minimal amount of current from the Pi itself. By sharing ground between power and data circuits you are making them "safe" to interact - as long as they are both DC circuits.

The result

neopixel strip to raspberry pi

Sorry for the crude drawing!

I would power the Raspberry Pi from a separate USB power supply (not from an expensive laptop during testing, though!) Were the LED strip, cat, hampster or Roomba misbehave and short the 10A supply then the Pi would keep running. With other types of load you could also experience line noise, interference or dangerous spikes. Rule of thumb; keep them apart.

Also some possible reasons for the Rasplosion;

  • Using an AC power supply (a possibility based on your colours)
  • Connecting a 5v supply to the 3.3v GPIO pin (from the comments :) )
  • Connecting two power supplies (something I would do)
  • Drawing 10A from GPIO (not likely from your photos)
  • So why does this diagram learn.adafruit.com/assets/13630 show connecting the power from the 5V 10amp power supply to both the power on the LED strip and the 5V power on the led? Is it because in that diagram that are not powering their pi independently? In my case I was powering my pi independently so I take it it's unnecessary to connect the power and ground from the power supply to my pi in my case. – Catfish May 10 '16 at 20:05
  • 2
    @Catfish ... ouch ... you are correct that in the image their thinking is to power the Pi AND the Neopixel strip from the external 5V power supply and as NoChecksum suggests, two sources are safer. However ... you just said something important ... look again at the web page you are showing from Adafruit ... notice it says "Don't use the Micro USB connector for power". You must NEVER connect an external source AND a USB power source to power the Pi. Smoke will ensue. – Kolban May 10 '16 at 20:13
  • @Kolban See that statement confuses me a lot b/c it also says "Connect to LED strip AND Pi". It seemed odd to me, but i did it anyways and poof! So you're saying that the statement "Don't use the micro usb for power" means not to power the LED strip from the micro USB port on the pi? – Catfish May 10 '16 at 20:48
  • 1
    I think what I'm saying is that you can power BOTH The Pi and the LED strip from an external 5V source (make sure you connect to the 5V line and not the 3.3V line). However.... if you do THIS ... then DO NOT ALSO try and power the Pi using an external USB to the Pi power input. – Kolban May 10 '16 at 20:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.