Weird bug alert: A simple xenon camera flash can crash a Raspberry Pi 2

Shawn Knight

TechSpot Staff
Staff member
The $35 Raspberry Pi 2 launched earlier this month sporting a wealth of upgrades and apparently, one of the most peculiar hardware bugs in recent memory.

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Scshadow

TS Evangelist
Thats great and all but isn't that why we encase all our electronics in chassis? I wouldn't just buy one of these chips without some cheapo case to cover it.
 
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Engineer

TS Rookie
Engineers of Earth your attention please!

Optosensors 101

These, quote:
"...flashes of high-intensity, long-wave light – like those emitted from a laser pointer or a xenon flash from a camera – cause the chip ... regulating the processor core power to momentarily get confused and thus, lose power...."
via PHOTOELECTRIC emissions induced by (direct) light.

Like a solar cell, this power regulator IC chip assembly -has semiconductor substrate- emits electric current under certain light -- as most semiconductors do, when light shines on them.
Seems the IC package has poor-or-nil optical insulation. Certain wavelengths may go through plastic.
...plastic shine through? pass-light package...??? (web image)

And so does ALL alpha, beta, gamma, neutron (ionizing) radiation (from space). Special packaging -non plastic- is called rad-hard.
If the IC in question is encapsulated/packaged in a plastic injection-mold package, the plastic (black? , above) package may pass certain optical wavelengths, or may even focus/lens effect/ them on the silicon IC die.
Essentially the whole package-silicon die combo acts as a photo diode, a photo sensor, a photo receiver.
Optical/laser LED computer mice use LED light to shine on the rotating/moving mice parts and use photo-diode sensors to sense the XY reflected light movement.

All under-the-microscope semiconductor die probing with needles I did was done under zero-light conditions (black hood) to prevent these always occurring photoelectric currents.
We did turn all lights off (probing all exposed silicon) to probe voltages & currents correctly, to avoid photoelectric-added contributions.
http://www.tezzaron.com/media/wafer.jpg = web image used as example of IC probing under microscope light = needle probes positioning.
TA! DA!
 
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wiyosaya

TS Evangelist
Wow.
Reminds me of what a big solar flare could do.
It is a similar effect, but not really the same.
Thats great and all but isn't that why we encase all our electronics in chassis? I wouldn't just buy one of these chips without some cheapo case to cover it.
Actually, besides physical protection, the reason most electronics are encased in a chassis is to prevent EM waves from emanating from the device and causing interference with other, nearby electronic devices. Most semiconductors have some sort of plastic or ceramic case around them and would be immune to this effect. It is too bad that the picture of the board is blurry and does not really show any detail of the chip in question.
 

VitalyT

Russ-Puss
No biggie here, placing a piece of black tape on the chip or bottom of the cover will resolve this.
 

MannerMauler

TS Addict
No biggie here, placing a piece of black tape on the chip or bottom of the cover will resolve this.
LOL! I was going to say something like this.

Well, if you have a 3D printer lying around the house and don't wan't ugly electric tape on your Raspberry PI, get the rough dimensions of the the chip in question and 3D print a cover for it.
 

lipe123

TS Evangelist
No biggie here, placing a piece of black tape on the chip or bottom of the cover will resolve this.
No biggie here, placing a piece of black tape on the chip or bottom of the cover will resolve this.
The problem is in the design. If they were that sloppy what other mistakes have they made.
They don't manufacture the chips they buy them wholesale from other electronics distributors.

So really your misguided insult is just.. misguided.
 

cliffordcooley

TS Redneck
The problem is in the design. If they were that sloppy what other mistakes have they made.
It seems some of us have forgotten the initial purpose behind the Raspberry PI. I think any and all mistakes are forgivable, in an electronics valued at only $35. Especially when the initial intended use was for hand-on training in a class room.
 
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wiyosaya

TS Evangelist
The problem is in the design. If they were that sloppy what other mistakes have they made.
It seems some of us have forgotten the initial purpose behind the Raspberry PI. I think any and all mistakes are forgivable, in an electronics valued at only $35. Especially when the initial intended use was for hand-on training in a class room.
Yes. And just because some dolt figured out that his Raspberry PI 2 needed help taking a selfie and exposed this photoelectric effect flaw does not mean that everyone who uses the PI 2 are going to provide the same assistance to theirs in its selfie taking quest since doing so would make the PI sick.