Miniature WiFi Weirdness
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Miniature WiFi Weirdness

by robreeves49 on Sat Mar 09, 2013 3:01 pm

For several weeks, everything worked fine. Then I left the RPi powered on for several days, and lost wireless connectivity.

I had a webcam and the wireless adapter in the two USB ports, no powered hub, both had been working fine.

Tried a powered hub, still does not work.

I have two of the wireless adapters, they both work elsewhere, and I have swapped both into the RPi

The strange thing is that the wireless adapter now gets VERY hot when plugged into the PI, it does not when used elsewhere.

The webcam still works.

USB blown?
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Re: Miniature WiFi Weirdness

by adafruit_support_rick on Sat Mar 09, 2013 3:51 pm

You really don't want to plug anything that requires a lot of juice directly into the Pi. WiFi dongles and webcams aren't a good idea. Even some keyboards draw too much power.

The RPi Verified Peripherals page lists various types of peripherals which are either known to work or are known to cause problems.

You might want to have a look at this discussion of power supplies and power problems.
Here is another page which discusses what the blinking LEDs indicate, and offers some tips on diagnosing power problems.
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Re: Miniature WiFi Weirdness

by robreeves49 on Sat Mar 09, 2013 6:22 pm

I don't see the OurLink Wireless USB adapter that Adafruit sells on either list.

I appreciate your perspective, but I'm still hung up on "worked fine for a few weeks, and not does not" and the fact the the adapter gets extremely hot.
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Re: Miniature WiFi Weirdness

by adafruit_support_rick on Sun Mar 10, 2013 11:16 am

How about the USB chip on the Pi? Does it get warm? It's the large chip directly adjacent to the USB jacks.
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Re: Miniature WiFi Weirdness

by robreeves49 on Tue Mar 12, 2013 7:13 pm

Good question.

I was going to re-flash the SD card, I suspect something is pinning the adapter "on" (but I'm a software guy, so that's the way I think) . It's recognized, but does not pull an IP address.

But I'll check the temps on the adapter and on the USB chip before I do that. Might have to wait until the weekend.

Remember, the adapter works fine elsewhere, and the camera still works fine on the Pi. So I don't think any hardware is blown (yet).
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Re: Miniature WiFi Weirdness

by adafruit_support_rick on Wed Mar 13, 2013 9:45 am

Apparently, it's normal for the USB/network chip to get really hot. I'm wondering maybe, if it's blown, the chip doesn't get hot but the dongle does.

What are the LEDs on the Pi doing? On/off/blinking?
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Re: Miniature WiFi Weirdness

by robreeves49 on Wed Mar 13, 2013 8:12 pm

Ambient temp 72F
Camera and WiFi Adapter plugged in
Camera working
USB Chip 110F and climbing
Wi Fi Adapter 150F !! and climbing

After removing Wi Fi Adapter
Camera working (in either USB port)
USB chip 110F - about the same.

Wi Fi adapter works elsewhere, not blown. Temp about 112F

RaspPi LEDs nicking and nacking as you would expect with a wired network connection.
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Re: Miniature WiFi Weirdness

by adafruit_support_mike on Wed Mar 13, 2013 9:22 pm

Tagging in to get a second set of eyes on the issue..

I think we all agree that something is wrong. A WiFi dongle in normal operating conditions shouldn't be able to brew a mean cup of tea. The fact that the dongles work elsewhere isolates the problem to this specific RasPi.

My question is whether the voltage across the USB supply pins has gotten reversed, and the heat is a sign of input protection diodes pumping a lot more current than they really want to. That's peripheral to the question of whether the device is (pardon the term) toast though.

My vote is to swap that one for another and hoist the thing up on a tiny grease rack to see what's going on.
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Re: Miniature WiFi Weirdness

by robreeves49 on Thu Mar 14, 2013 4:51 am

I'll check the USB supply voltage, but the Pi just spent the night running with the camera plugged into the USB port, and it's happy as clam this morning.
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Re: Miniature WiFi Weirdness

by adafruit_support_mike on Thu Mar 14, 2013 3:22 pm

Paraphrasing to make sure I understand:

- The Pi works fine with a webcam plugged into the USB socket
- The wifi dongle works fine when plugged into another device
- Putting the wifi dongle in the Pi's USB socket makes the dongle heat up

You said you tried a powered hub. Again, to avoid tripping over the obvious, I take that to mean you plugged a powered hub into the Pi's USB port and plugged the webcam/wifi dongle into the hub. Webcam worked, wifi didn't.

If all those statements are correct, this is starting to sound like an integration problem (only shows up when you put things together).
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Re: Miniature WiFi Weirdness

by robreeves49 on Thu Mar 14, 2013 3:49 pm

All true - except that the dongle does not work/heats up even with the camera removed.
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Re: Miniature WiFi Weirdness

by adafruit_support_mike on Fri Mar 15, 2013 1:03 am

Follow-up question: does the dongle get hot when it's plugged into a powered hub, physically remote from the RasPi, when the hub is plugged into the RasPi's USB port?

If so, we've eliminated the RasPi, the dongle, and the RasPi's USB jack as obvious sources of failure. The list of remaining sources includes voodoo, deep magic, and gremlins.
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Re: Miniature WiFi Weirdness

by robreeves49 on Fri Mar 15, 2013 5:55 am

voodoo, deep magic and gremlins it is, because the dongle gets hot in a powered hub also.

This weekend's project will be to check a few more voltages and then re-flash the software. I just have this weird feeling that something is a few bits off.
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Re: Miniature WiFi Weirdness

by lucentminds on Fri Mar 15, 2013 10:08 am

I have the same device. I just got around to testing it with my pi today. If you put it in as the only usb item, the entire pi dies. If you take it out the pi works fine. If I try and use the dongle in my PC, Windows doesn't even show it in the device manager. Take the dongle out of the PC and it burns to the touch. I hope it's still useful for something.
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Re: Miniature WiFi Weirdness

by adafruit_support_rick on Fri Mar 15, 2013 10:51 am

@lucentminds - did you purchase the dongle here?
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