USB drawing too much power?

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saarahs
 
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USB drawing too much power?

Post by saarahs »

Hello,

I've been working on a neopixel project. I soldered three neopixels together in a chain, and when I plugged in the USB, my macbook gave me an alert that said the USB was drawing too much power. I've tried on different computers and the serial port just doesn't show up. The Arduino's power light comes on, but the neopixels stay off and I can't upload any code. I checked the soldering and wiring and it looks ok. While prototyping before soldering, everything was working fine, so I'm not sure what the problem is.

Thanks!
Saarah

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adafruit_support_mike
 
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Re: USB drawing too much power?

Post by adafruit_support_mike »

Post a photo of your hardware and connections and we'll take a look.

Three NeoPixels should have an upper limit of 180mA, which is well below the level a USB port can handle.

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saarahs
 
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Re: USB drawing too much power?

Post by saarahs »

Thanks for the quick reply! Here are some photos. I have them on a board, so the wiring and connections are on the back. Let me know if you need more.
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adafruit_support_bill
 
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Re: USB drawing too much power?

Post by adafruit_support_bill »

Can you post some close-ups of the front of the rings? I suspect you may have a solder-bridge between one of the power or ground connections and a pin from an adjacent pixel.

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Franklin97355
 
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Re: USB drawing too much power?

Post by Franklin97355 »

3 rings x 16 pixels x 3 LED per pixel x .02 amp per LED = 2.88A well more than a USB port can provide.

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saarahs
 
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Re: USB drawing too much power?

Post by saarahs »

Here are some closeups. Also, the Arduino's USB serial port is not showing up, even when I've disconnected everything.
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adafruit_support_bill
 
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Re: USB drawing too much power?

Post by adafruit_support_bill »

In your third photo, it looks like a possible solder bridge between the VCC connection and the pixel to the left of it.
Also, the Arduino's USB serial port is not showing up, even when I've disconnected everything.
An overloaded port USB might take a few minutes before the polyfuse resets. The 2.88A calculation is for worst-case (all pixels full intensity white). Typical usage is 1/2 to 1/3 of that, but still more than the 500mA most ports can provide.

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saarahs
 
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Re: USB drawing too much power?

Post by saarahs »

Good to know that my USB port should be ok!
How would I go about fixing the solder bridge? I've only soldered a few times before, so I'm very new at this!

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adafruit_support_bill
 
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Re: USB drawing too much power?

Post by adafruit_support_bill »

That looks like a fairly small one bridge. You can probably just take a clean, hot soldering iron and drag the tip between the pixel and the VCC joint. Often that will pull enough solder away to break the bridge.

If not, you can use some solder wick or a 'solder sucker' to remove the excess.
https://www.adafruit.com/product/149
https://www.adafruit.com/products/148

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saarahs
 
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Re: USB drawing too much power?

Post by saarahs »

Ok, I will try that and see if it works.
Would you mind looking over my soldering for my other project as well? It's a motorshield, and I just want to make sure I don't ruin it when I plug in the power.

Thanks for your help!!
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adafruit_support_bill
 
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Re: USB drawing too much power?

Post by adafruit_support_bill »

That looks pretty good. I don't see any solder bridges or anything that might cause damage. There are a couple of possible 'cold joints' which can cause problems communicating with the shield. On the upper right side of your photo, there is a row of pins labeled 8 through SCL. Some of these have a 'frosted' appearance which can indicate a cold joint. This guide has tips on identifying and fixing such problems: http://learn.adafruit.com/adafruit-guid ... n-problems

Note that for the Motor Shield, the important pins for motors are: +5v, GND, SDA and SCL. Pins 9 and 10 are important if you are using the Servo connections.

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Nebulus
 
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Re: USB drawing too much power?

Post by Nebulus »

Hey,

I experienced this problem on my neopixel strip setup as well. MacBooks just can't handle the awesomeness of neopixel power. If you are looking for a quick not super technical fix:

1. Obtain external power supply for arduino. 9v battery will work or I am using 12DVC 500mA adapter
2. Restart computer if you haven't already.
3. Sync all necessary code to Arduino from computer.
4. Unplug Arduino from computer.
5. WARNING: Whatever you do dont plug in power before everything is connected. Minimally to ground on your Arduino and pixel strip.
6. Power it up. The strip and arduino will run on separate power supply and will run whatever code you last put on there.

The inconvenience of this method having to unplug and recode every time you want to change the pixel display as well as having to locate external power. But yeah, Ive crushed my MacBook Pro too many times using arduino and honestly arduino programs have been the only thing that causes my mac any trouble. Its worth it in my opinion to code everything first to an unplugged arduino and then wire it up and power it separately. Trust me on this, my mac has shut down, disabled the USB drive and I couldnt turn it on for nearly a week. Power it up separately ;)

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