Tinue
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Pi Zero: What gets damaged by a broken USB device?

Fri May 13, 2016 1:25 pm

My Pi Zero stopped working all of a sudden. When I connect it to power the SOC gets hot quickly, but nothing else happens.

To test, I connected the USB WLAN Stick that I was using on the Pi Zero to a Pi 2: The Pi 2 reported that a USB device uses too much power, and the WLAN stick got very hot. Obviously the stick is broken.

Apparently the Zero has no protection against a USB device that draws too much power (or possible even has a shortcut).

Is there a chance to resurrect the Pi Zero? What could have been broken? Visually, there is nothing wrong.

Usually I wouldn't bother about 5$ worth of equipment, but it's a bit difficult to find a replacement these days...

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RaTTuS
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Re: Pi Zero: What gets damaged by a broken USB device?

Fri May 13, 2016 1:38 pm

monday is replacement day
you have shorted some gpio or put >3.3V onto GPIO or done some other badness involving metal and the board

no chance to rescue it it,it is now an ExPi
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hippy
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Re: Pi Zero: What gets damaged by a broken USB device?

Fri May 13, 2016 1:42 pm

Tinue wrote:Is there a chance to resurrect the Pi Zero? What could have been broken?
As full circuit diagrams are not available it is hard to say.

Drawing too much current through USB or a short of the power rails in the USB device should not cause a failure of the SoC. Some other fault could affect the SoC pins which connect to the USB data or OTG signalling pins; I am not sure if there are any current limiting resistors fitted to mitigate against that or not. Even if there they might not protect against a short to 5V.

If the SoC pins have been damaged or destroyed it's probably 'a gonner'.

Tinue
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Re: Pi Zero: What gets damaged by a broken USB device?

Fri May 13, 2016 2:38 pm

I was hoping the thing is just stunned. I'd love to replace it, and I am sure one day I will be able to. For now, I'll have to continue my little project with a Pi 3.

When I measure the resistance between 5V and Ground it's close to zero (I think 1-2 Ohm), so apparently something shorted out.

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RaTTuS
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Re: Pi Zero: What gets damaged by a broken USB device?

Fri May 13, 2016 2:44 pm

what had you plugged into it ?
could you have shorted the board out on something ?
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Tinue
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Re: Pi Zero: What gets damaged by a broken USB device?

Fri May 13, 2016 7:24 pm

The exact wiring and the board itself is documented here: https://github.com/tinue/APA102_Pi. This worked fine many times. Today I wanted to upgrade to the new Jessie version and plugged the power supply in, and nothing worked anymore.

After the Pi stopped working I checked the power supply, but there is nothing wrong. The level shifter is fine as well, I checked everything there. It does appear as if the USB WLAN Adapter spontaneously blew up, and killed the Pi Zero along the way. Maybe the adapter from USB-Micro-B to USB-A female used to connect the WLAN stick was not 100% plugged in to the Pi Zero, but I can't check this anymore.

The WLAN Stick does work (i.e. it does connect to WLAN), but it uses way too much power, and it gets very hot very quickly. I've thrown it away now, of course.

masa-aud
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Re: Pi Zero: What gets damaged by a broken USB device?

Sat May 14, 2016 9:35 am

reply to tinue on Pi Zero:What
I think that simply a set of volt-meter and ampere-meter knows the answer and you will well be guided to a good next step.

masa

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