Xenon Flashes Can Make New Raspberry Pi 2 Freeze and Reboot

An anonymous reader writes Unfortunately for Raspberry Pi 2 owners who are trying to photograph their devices, ... the Raspberry Pi 2 has been found to be Xenon flash sensitive. Any camera with a Xenon flash aimed at the device is causing the device to freeze for a few seconds before rebooting. The forum thread about the bug is an interesting play-by-play of how the problem was narrowed down.

Comments

SMPS?

[SuricouRaven]

Cool. The linear reg on the previous models worked perfectly, but was rather less than ideally efficient - 5V power in, but almost all the power consumed goes via the 3.3V rail.

Maybe not the power supply?

[Wierdy1024]

Reports are saying the power supply is causing this fault.

That might not be the case. Bright UV light will create electron hole pairs in the gate of transistors turning them all *on*, which will cause the chip to use much much more power since push pull output stages of logic gates will now be shorting the power supply.

Hence, even though it looks like the power supply is failing, it could simply be the power supply is turning off due to overcurrent.

Re:Maybe not the power supply?

[itzly]

Hence, even though it looks like the power supply is failing, it could simply be the power supply is turning off due to overcurrent.

No. Covering the regulator chip solves the problem. That means that it is the culprit.

Re:Maybe not the power supply?

[Mal-2]

If that was the case, putting a blob of material on the power supply chip (and nothing else) wouldn't remedy the problem – but it does (see the last post on this page.)

Re:Maybe not the power supply?

[Anonymous Coward]

This thread shows a quick experiment which confirms it's directly the light which is the cause, not the EM pulse from the capacitor discharge in the flashgun. Chip U16 apparently, which is part of the power regulator.

Re:Maybe not the power supply?

[Megane]

Interesting. That thread has reached a point where they're trying to confirm that it's just the edges of the chip that are light senstive.

A while back I took apart a scrap HD-DVD player and I noticed black epoxy around the edges of some chips. I thought it was just an attempt to prevent hacking the player, but I think those were the same type of flip-chip packaging, with nothing but mirror silicon on top.

Also I seem to recall that CPUs and other chips with a mirror silicon chip in the middle always have the silicon's edges covered.

Re:Maybe not the power supply?

[Aighearach]

I heard that if you color the edges of the chip with a blue sharpie, then your RPi mp3 player will have cleaner sound. /s

I was recently working with some LED lighting modules with the bottom of the PCB exposed (and holding the LEDs) and the constant current controller had a big blob of epoxy on it. The other model where the LEDs were mounted on a different board, with the controller inside a metal housing, didn't have that.

Re:Maybe not the power supply?

[cdrudge]

I don't know about cleaner sound, but if you use a red sharpie the sound will be warmer.

I can't seem to find it now, but I remember seeing a product review I think on Amazon that was exclaiming how awesome some ridiculously priced optical cable was for a audio system because the fiber optic cable had a red tint to it imparting a warmer sound for the listener.

Re:Maybe not the power supply?

[marcansoft]

Usually, "epoxy" around the edges of a BGA chip is neither an anti-hacking attempt nor a light-proofing attempt. It's called underfill, and its chief purpose is to increase mechanical strength and make the bond more durable than tiny bare solder balls would be on their own.

Re:Maybe not the power supply?

[Muad'Dave]

Not all plastic or glass that's opaque to visible light is opaque to UV.

Bring out the tinfoil

[thue]

I am guessing that wrapping it in tinfoil would fix it? I know it works great for stopping the mind-control waves from getting into my head.

Re:Bring out the tinfoil

[Anonymous Coward]

The trick is to filter out the government / nwo mind control waves while still allowing youself to recieve signals from the cosmos.

Re:Bring out the tinfoil

[Anonymous Coward]

Aluminum foil is cheaper, more available, and has better conductivity fo EMI shielding. Only a complete asshat would use a foil made from Tin.

Re:Bring out the tinfoil

[towermac]

AC is a coverup minion for them. Every good consipiracy buff knows that tin indeed blocks the mind control rays, as opposed to aluminum. Which is why they did away with tin foil, and replaced it with aluminum. Go ahead, try to find some tin foil nowadays...

Re:Bring out the tinfoil

[Kaenneth]

"human"

Found the lizard person.

Re:Bring out the tinfoil

[kenai_alpenglow]

Took a while, but I found some for you. http://www.alibaba.com/product...

Re:Bring out the tinfoil

[Aighearach]

Tin foil is easier to solder onto the board.

Re:Bring out the tinfoil

[bobbied]

You need a full head covering there, not just a hat to avoid the mind control fields..

You need to make sure to cover all the way down, well past the neck with foil, making sure it is air tight with no holes and tightly sealed at the bottom. It doesn't need to be tight fitting, just 100% sealed...

You will know you are doing it right if you start to feel light headed and out of breath. That's just the mind control waves wearing off and your brain returning to it's normal state.

When you do this, take a video and pictures and leave a note for your friends to upload them to the Darwin Awards site...

Re:Xenon? Should have used a Xeon.

[Anonymous Coward]

They should have used Silverlight instead of Flash.

The new power supplies may be sensitve to EMP

[Anonymous Coward]

Years ago when I visited an aquarium I encountered a very strange situation

I was in front of a tank which has 3 electric eels, and in front of the tank there was a 'meter' measuring the power the electric eels were discharging

So I took out my camera (real camera, with powerful Xenon flash light module attached)

Before I pressed the button the Xenon flash was charging (as I said, powerful flash light) and all of a sudden the 'electric meter' in front of the tank indicated that there was an electric discharge from the electric eels

At first I thought it was a coincidence. Then I wanted to take another picture. Again, my Xenon flash light module was charging, and again, there was a jump in the 'electric meter' reading. This second time around I started to suspect that there was a connection in between my Xenon flash light module and the electric eels

The third time around I only use the Xenon flash module. Again I hold it close to the tank, and charge it, and again, the 'electric meter' got another 'shock'. I repeated the experiment the fourth time, fifth time, .... every single time while my Xenon flash module was charging up,. the electric eels inside the tank somehow 'felt' something and gave an electric discharge

I never know the exact reason. My suspicion is that there might be some EMP effect, some wave or some magnetic field, or something like that

What I described happened years ago. I never get the chance to test out my theory

Perhaps someone can test if Xenon flash emits EMP, or not

Re:The new power supplies may be sensitve to EMP

[Enry]

Back in the earliyish days of cell phones (1994ish) I had a cell phone that would cause my computer speakers to power off about a half second before the phone would ring.

Re:The new power supplies may be sensitve to EMP

[Anonymous Coward]

Or maybe the glorious eels didn't give a shit about your puny human flash, but your device was interfering with the meter.

Re:The new power supplies may be sensitve to EMP

[mark_reh]

I think it is more likely that your flash unit was disturbing the sensor than the eels.

Re:The new power supplies may be sensitve to EMP

[Anonymous Coward]

My cellphone would make any nearby speaker go "chik chika chik chika chik wrrrrr" just before the phone rang.

Re:The new power supplies may be sensitve to EMP

[mgscheue]

Yep, I remember mine (Motorola? Nokia?) did that, too.

Re:The new power supplies may be sensitve to EMP

[CronoCloud]

Yep, early motorola and nokia here too.

Re:The new power supplies may be sensitve to EMP

[An dochasac]

Put your electronic flash next to an AM radio (you might find one in an antique shop ;-) You'll find considerable EMF comes from the electronic flash circuit as it charges the big capacitor. For fun we used to heterodyne this against the EMF from an LED pocket calculator for some very bizarre spacy effects.

Re:The new power supplies may be sensitve to EMP

[thegarbz]

I still have on my desk now a modern 3watt UHF digital 2-way which causes a lot of monitors to turn off when I key it up.

There's nothing really about this phenomenon which links it to age. Modern equipment and old equipment can be affected.

Re:The new power supplies may be sensitve to EMP

[Anonymous Coward]

I've worked with Nd:YAG lasers that had large xenon flashlamps in them (in principle like a camera's flashlamp, but much bigger, 100s of kW for a sizable fraction of a second), and pretty much any voltage monitoring in the room would pick up spikes from the start and end of the flash, even with a metal cover over the laser. Any large changes in current and unshielded inductance, and you will get some mess of EMI coming off. I doubt it would be enough to damage anything, unless you had a giant antenna feeding directly into silicon that was within a 100 mV of a damage threshold and no protection scheme.

But sometimes it doesn't take much to confuse some chips and get them into a state they are not supposed to be in. I've seen plenty of driver chips that will, to the detriment of what they are connected to, latch up in noisy environments. They turn on, but don't turn off when the input signal is turned off. I would expect a SMPS to be somewhat robust to such noise considering how often they get used in half-ass designs that spew out plenty of EMI. But I've also seen some of the higher frequency ones that use rather large resistors for feedback, with a feedforward capacitor of just a couple pF, which is small enough it means if unshielded, moving your hand close to the circuit changes output voltage slightly and even the stability if poorly laid out on the board. Even then, it would take a whole mess of layout problems and things being marginal for that to affect the operation of digital logic.

Some one should use this though to run a VIC-20 emulator... then I could relive not so found memories of an experiment I once worked on that would cause the VIC-20 to reboot every time it fired.

Re:The new power supplies may be sensitve to EMP

[Electricity Likes Me]

It's the pulse rate of the radio. The radio turns on and off at audio frequencies, so the interference smears out to become the classic chirp sound.

Re:The new power supplies may be sensitve to EMP

[SScorpio]

It's related to the GSM network, if you had a CDMA phone (Verizon, Sprint) you didn't experience the issue.

The problem wasn't only over the radio, it also affected computer speakers and headphones. The expanded frequencies the networks use might help the problem, but I've been on CDMA for the past eight years, so I experienced it for a while.

Re:The new power supplies may be sensitve to EMP

[wolrahnaes]

That's because you're hearing the pulsed transmission of a TDMA radio technology.

D-AMPS (AT&T pre-Cingular), iDEN (Nextel), and any GSM 2G (up to EDGE) all use/used TDMA to share the frequency, so they're all potential causes of this.

These days you won't hear it much because D-AMPS and iDEN are both dead and most GSM phones will be attempting to connect on 3G UMTS (which uses CDMA) or 4G LTE (OFDMA).

DECT cordless phones are heavily derived from GSM so it's possible that they may be able to cause the same behavior, but due to their significantly reduced range requirements the power probably isn't there. I haven't heard it from my DECT phones.

Re: The new power supplies may be sensitve to EMP

[Anonymous Coward]

Whether they have eyelids or not doesn't matter, since the typical flash duration, 10 ms, is less than the typical time it takes humans and various animals to blink in response to an external stimulus, 20-50 ms.

Re:The new power supplies may be sensitve to EMP

[Solandri]

OP is correct about TDMA being phased out for data services on cell phones. TDMA is a terrible way to share bandwidth because you have to allocate bandwidth to devices which may not need to transmit anything during their timeslice. In CDMA and OFDMA, phones transmit simultaneously, and the bandwidth is automatically divided between them. The transmissions from other phones are just an increase in the noise floor for the orthogonal signal of your phone. So each additional phone transmitting decreases the SNR for any individual phone, thus automatically dividing up the bandwidth.

GSM voice calls are still done over TDMA though. It limits the number of and range at which phones can communicate with a single tower. But voice is low bandwidth enough that these drawbacks haven't been as limiting as for data services.

Re:The new power supplies may be sensitve to EMP

[davester666]

I believe that effect is known as "improper shielding".

Re:The new power supplies may be sensitve to EMP

[Nyder]

Back in the earliyish days of cell phones (1994ish) I had a cell phone that would cause my computer speakers to power off about a half second before the phone would ring.

Yep, same here

Re: The new power supplies may be sensitve to EMP

[jsveiga]

In the US, in medieval times, cell phones used TDMA (IS136) or CDMA (IS95/2000).
TDMA is time-division multiplex, which means the phone radio would turn on and off on a fixed cadence to allow for other phones to share the same frequency channel. At the start of a call (either to or from the cell phone), the cell network still doesn't know how attenuated the phone signal will arrive, so typically the first communication bursts from the phone would be sent with much more power than the subsequent ones, when the cell could tell the phone "whoa, you can lower your voice, I can hear you very well" (power control).
That was why the phones would interfere with other devices just when a call was about to start (before the phone rings, the cell and the network have already established comms).
Europe was right, and everybody went GSM, which then added WCDMA (UMTS, LTE, "3G", "4G").
GSM is also a TDMA technology, so when your phone is in GSM mode, it may also create the same tick-tick-tick-brrrrrz interference for the same reasons.

Re: The new power supplies may be sensitve to EMP

[jsveiga]

The radio frequencies are high, but the turning off/on of the radio transmitter, not.
It is that keying of the power amps which caused the audible buzz.

Re: The new power supplies may be sensitve to EMP

[Anonymous Coward]

A modulated high frequency signal has no low frequency components, only frequencies near the carrier wave frequency. No amount of linear filtering will convert a modulated high frequency signal into a lower frequency one, as the previous parent did. You need something nonlinear, like a rectifier. But also as already said, sources of nonlinearities in amplifier circuits and audio circuits are really common. It isn't just the power side of things doing that (otherwise your speakers would be picking up a lot other stronger sources in a typical house or office), but is the RF getting downconverted.

Re:The new power supplies may be sensitve to EMP

[Enry]

I'm sure that's the case, but I've never had a cell phone since that had that kind of an effect on other systems.

Re: The new power supplies may be sensitve to EMP

[BronsCon]

You don't understand how TDMA works, do you? Let's say the carrier is 800MHz, 100 slots. That means each TDMA radio on a channel will only transmit for 1/200 of a second, sleep for 99/200 of a second, listen for 1/200 of a second, sleep for 99/200 of a second; essentially it's active for 1/100 of a second each second, leaving the channel open for 99 other users for the remainder of that second. It is that switching on and off that you hear; the radio blasting its transmission 100 times per second, a 100Hz carrier with an 800MHz subcarrier (I know this seems wrong, since a subcarrier is typically lower in frequency than the carrier; it is wrong, but it's the best wording I have to describe how TDMA actually works).

Mind you, I'm pulling the 100 slots thing out of my ass, it's probably much closer to 1000.

As for the pulsing, it's transmitting, waiting for the tower to process and reply, then transmitting again. I'm sure you've noted that the frequency stays roughly the same, while the pulse width changes, then the pulsing stops and you are left with a solid signal, shortly before power adjustment completes and the interference fades.

Re:The new power supplies may be sensitve to EMP

[ganjadude]

that still happens with some phone signals in cars today

Re:The new power supplies may be sensitve to EMP

[Jerry Coffin]

Minor technical correction: on 4G/LTE, the tower transmits to the handset using OFDMA, but the handset transmits to the tower using SC-FDMA. Admittedly, the difference is fairly minor--mostly one extra inverse FFT step. It does, however, reduce the ratio of peak to average transmission power, which is useful on power-constrained devices (like most handsets).

Re:The new power supplies may be sensitve to EMP

[Aighearach]

My cell phone still does that if I put powered speakers near it. Pretty much only would be close enough if they are computer speakers on a desk, most other audio setups with powered speakers aren't close enough to the places in the room where cell phones get set down.

If the effect is at all reduced in modern equipment, it is probably just that shielded cables got cheaper, or computer speakers are using smaller wires that pick up less interference.

In the 90s it was common for CB radios from passing cars to "bleed over" onto televisions. The CBs are the same now as they were then, but it is very unlikely you'll still get interference, because the TVs are designed better.

Re:The new power supplies may be sensitve to EMP

[Aighearach]

Because the "systems" have evolved to be tolerant to the common frequencies of interference.

The signal strength has mostly gone up, not down, so without the improvement of the equipment receiving the interference, the problem would be worse now.

Just take a cheap powered computer speaker, remove the speaker wires, replace with the speaker wires from a 90s computer speaker, and place a cell phone next to it. You'll pick up lots of interference just off the unshielded wires.

Home stereo equipment picks up less interference in most cases because the long wires contain the fully amplified signal, which swamps most of the interference. In a powered computer speaker, the unshielded wires are at line level, and the amplification happens inside the speaker box, so the interference gets amplified along with the audio signal.

All it takes is either a shielded cable, or smaller wires, and the interference goes way down.

Re:The new power supplies may be sensitve to EMP

[cheater512]

That is a feature. Auto speaker mute when you have a call. :)

Re:The new power supplies may be sensitve to EMP

[Anonymous Coward]

This is same AC who posted the original comment

Of course I am not the eel, I can't tell if they give a shit about me or not

But what I can tell you is this, every single time my Xenon flash module was charging up, the eels (all three of them) turned to face me, as though they 'felt' something

And then, one or more of them started to discharge (sometimes 1 spike in the meter, sometime 2 spikes, and in the subsequent 'experiments' I saw multiple spikes)

I can not tell you how the multiple spikes came by --- I do not know if all three eels doing their discharges, or one eel did multiple discharge, or some combination of that

All I know is, if I did not charge that powerful Xenon flash module, the eels did what they did, swam here, there, everywhere, but once I started the charging process, all the three electric eels turned to face me, all three of them

As I mentioned in my original comment, I didn't know if it was EMP or whatever, it was just something curious that happened, and I do not have any scientific explanation for it

I just lay it bear here for all - maybe some of you have the equipment or knowledge or both, or maybe you know people who can carry out similar experiments - you guys can go out and run the tests and see if there is any connection or not

That is all I can tell you

Re: The new power supplies may be sensitve to EMP

[BronsCon]

And even if it was spewing a huge amount of low frequency components out, good look getting much of that to couple into a audio system a meter away without only a watt of power and a cell phone's antenna

The AC before me said everything I want to say, except for this: clearly that works, since my old TDMA phone used to be able to make my computer's speakers buzz when they were turned off at the power strip they were plugged in to. You can theorize incorrectly all you want, but the best test of real world physics is the real world.

Re:The new power supplies may be sensitve to EMP

[dougmc]

To be fair, most cell phones emit less than a watt of power rather than three.

Re: The new power supplies may be sensitve to EMP

[ceoyoyo]

Of course it does. Since you mentioned Fourier analysis, do you know what the Fourier transform of a delta function is? It's a constant. Yup, equal power at all frequencies. A knife edge also has power in all frequencies. If you're "turning something on and off" at 100 hz then you have a situation somewhere between a 100 hz square wave, which has power in all frequencies (less possibly a few nodes of destructive interference), and a 100 hz sine wave, with power at only 100 hz. Either way, 100 hz is present.

Re:The new power supplies may be sensitve to EMP

[JWSmythe]

I wouldn't read too much into the eel's behavior. There are too many variables that we can't confirm. They could have faced towards you out of coincidence; movement near you; your movement; changes in the sign; etc, etc, etc...

I think it's interesting that your flash set off the sensor. If you don't mind me asking, where is the aquarium?

I've noticed other odd things in the right conditions. Like there is a state park near here that has an underwater viewing area. My prescription sunglasses are polarized, so when I've gone into the tank, I could see distortions in some of the windows. Without the polarization, you can't see it.

I've only worn them in there because it's bright just outside. I wore them into the darker area because I need glasses to see, and it was still bright enough to not be stumbling around in the dark. Most people take off their sunglasses in there.

Re: The new power supplies may be sensitve to EMP

[assemblerex]

I still hear this in my 1990's era pc speakers when the police use their radios if they are nearby. Ticka ticka ticka (sometimes even the voice)

Re: The new power supplies may be sensitve to EMP

[bobbied]

Well, it's surprisingly easy to build a radio receiver. All you need is a rectifier and a bit of capacitance to convert RF into AC. Most Audio amplifiers have everything you need, except for the circuits that tune the receiver and an antenna. However, audio cables and "luck" can supply what you need for a receiver with very low sensitivity and suffer RFI from very strong RF signals nearby.

Re:The new power supplies may be sensitve to EMP

[bobbied]

Flash of genius? Blinding intellect?

Or, perhaps it was dark and the subject of the photo was not actually in the tank...

Re:The new power supplies may be sensitve to EMP

[bobbied]

Um.... No...

Technically it was the quick discharge of the capacitors that required a really high current at substantial voltage that jumped though an arc gap in the bulb. The arc and the quickly changing currents where what generated the EMF spike....

However, in the Pi2, the problem was light related. U19 isn't apparently shielded correctly from light and when the bright strobe light hits is it disrupts the 3.3v power supply regulation of the Pi2. When they block the light from hitting just that chip, all is well.

Re:The new power supplies may be sensitve to EMP

[bobbied]

Before anybody corrects me.. It's U16, not U19....

Re:The new power supplies may be sensitve to EMP

[Andy Dodd]

Are you sure the meter was registering the fish reacting to the flash unit, as opposed to simply registering whatever crap the flash was emitting as it was charging?

Re: The new power supplies may be sensitve to EMP

[Andy Dodd]

IIRC the GSM frame repetition rate was around 400-440 Hz.

Many electronics will, when exposed to RF like this, behave exactly like the legacy "crystal" radios did - these were nothing more than a basic envelope detector (diode + low pass filter) combined with a tuned resonator.

Hit a crystal radio with a lot of local RF (1/R^2 remember?) and it'll receive a "station" it's not tuned to.

Re:The new power supplies may be sensitve to EMP

[bemymonkey]

They still do this if you're on a GSM network.

Re: The new power supplies may be sensitve to EMP

[BronsCon]

Thanks for that. I understand well enough the principle by which it works, but I was unsure of the frequency and too lazy to look it up.

Re:The new power supplies may be sensitve to EMP

[p0larity]

A lot of electronic devices bleed off harmonics of their data bus as well. Many PCs with crappy audio hardware and bad voltage regulators will make noise through the sound card whenever you move the mouse or a particular program runs.

Re:The new power supplies may be sensitve to EMP

[thegarbz]

I do. Every cellphone I've had has caused interference to something at some point. Typically it has been audio electronics. The worst one was my car radio. I keep my phone (Galaxy S4 if it's of any interest) underneath the radio in a little compartment when I'm driving. I don't have a centre console in my car.

About 3-6 seconds before I get a text message I would hear a very loud clicking noise from the speakers and also lose AM radio reception.

Whenever you introduce something into the airwaves you will interfere with something. It's just a matter of how sensitive the target device is and if you're lucky enough that the frequency / power you are using will affect that device.

I built a power amplifier a few years ago as well and spent a lot of time trying to debug unstable oscillations. Turns out the bandwidth of the amplifier was set such that it was on the very edge of stability. My mobile phone at the time (Galaxy S) if it was in my pocket would drive the amplifier over the edge and start producing full wave oscillations at around 250kHz. It took a long time to debug why the system seemed to behave sometimes and not othertimes before I found the common cause was how close my phone was.

Though that can be put down to design error and a reduction in bandwidth solved the problem, interference is none the less a very real problem.

Re:Not Photosensitive

[Anonymous Coward]

A 100mW red laser pointer aimed at U16 also triggers it.
Unless you want to claim diode lasers now emit x-rays and low rise time EM pulses... it's light sensitive.
And inspecting U16 closely, it's no surprise. You're not looking at a plastic package but the laser marked underside of a bare die.

Claim to fame is important no matter how trivial..

[Trax3001BBS]

He only mentions that it crashes, everybody else answers the question yet he now goes by "Discoverer of the PI2 XENON DEATH FLASH !"

Re:Not Photosensitive

[Anonymous Coward]

Bingo, that's about what I was going to say. U16 is flip-chip bonded to the circuit board, meaning the naked die is exposed on the bottom. Even if it had a plastic or ceramic cover, it might still be photo sensitive to light getting underneath it. If the underside of the die (flipped, so topside) is really exposed, it basically becomes a silicium solar cell.

OMG!

[Anonymous Coward]

I took a picture of my Raspberry Pi 2, you'll never believe what happened next!

Re:OMG!

[MobSwatter]

And they said there was never any harm in a Japanese drive by. Raspberry Pi V2 killed by a bus load of tourists.

So put it in a case

[newsdee]

TFA found out precisely which chip it is (U16), covering it solves the problem.

Re:Claim to fame is important no matter how trivia

[jones_supa]

He is clearly overplaying it so probably just joking. :)

Enough!

[Anonymous Coward]

Stop using Flash, it's a persistent vulnerability, and Youtube has an HTML5 video player now.

Re:Enough!

[ArcadeMan]

When did Adobe sell Flash and who is this new Xenon company? Never heard of them.

Re:Enough!

[Uncle Warthog]

MOD THIS UP!!

Another good reason for OCD unboxing...

[jpellino]

a de facto EMP / light sensitivity torture test!

Re:Another good reason for OCD unboxing...

[newsdee]

Joke aside, with some many people getting one any problems are bound to pop up quite quickly (like this one).

Re:Another good reason for OCD unboxing...

[SuricouRaven]

I've had trouble before with EMP - one of the few here who can honestly say it was a true EMP, not just RFI. The device producing the EMP was a four-kilovolt capacitor bank used for creatively imploding aluminium cans and launching metal objects at quite dangerous velocities. It can put out enough of a pulse to crash a camera - all the control circuits are especially hardened against it.

Re:Xenon? Should have used a Xeon.

[allo]

ymmd

Nothing unusual really

[inflex]

There's plenty of cases of electronics misbehaving due to exposure to strong light. Glass enveloped diodes (such as signal diodes) can be notorious for it, as can the black plastic encased units if the light is strong enough.

Small bare CoG (Chip on Glass) LCD panels will crash / hang when you use the flash on the camera taking photos of them in operation ( same reason, the controller die is exposed ).

It's not EM-pulse or xrays causing the problem, just good ole silicon junctions being exposed to intense light :)

Re:Nothing unusual really

[VAXcat]

"There's plenty of cases of electronics misbehaving due to exposure to strong light"...Around a million years ago, when the earth was young and laser printing hadn't been invented yet, I was an electronics tech working on phototypesetting machines. These machines (Mergenthaler VIPs) had a large zoom lens mechanism in them for producing different size print. One afternoon, a junior tech called me over because, he reports, "the zoom lens on one of the machines is going crazy". I get there and see that the zooms are running back and forth,. full speed, at random. I noticed the tech has a trouble lamp inside the machine. I turned it off and the lenses stopped their manic dance. He hadn't realized that the zoom lens travel was controlled by optical switches - the lamp turned them all on at once, producing the crazy bahavior.

Re:Nothing unusual really

[lars_stefan_axelsson]

It's not EM-pulse or xrays causing the problem, just good ole silicon junctions being exposed to intense light :)

Yupp. Einstein for the win! :-)

Re:Crap hardware, not surprising

[thegarbz]

Really not surprising. The pi2 is pretty crappy hardware. So many better micro computers for projects, not sure why 'geeks' obsess over it.

Oh wow. Random uneducated Pi bashing. Especially considering the device causing the problem is the latest and greatest in small SMPS chip regulators and nothing at all to do with any of the parts that are typically quoted in specs and bitched about by ACs on slashdot.

Re:Crap hardware, not surprising

[Lumpy]

He is probably one of those idiots that will tout the Beaglebone Black as superior....

A Raspberry Pi 1 will blow away a Beaglebone black in video playback or GUI rendering.

Re: EMI Noisy environments

[ArcadeMan]

Maybe he meant a lower model or RPi is more than sufficient. Some people are still using ATmega328P-powered Arduinos to control their 3D printers and those move a lot of a hell faster than most CNCs.

Re:Crap hardware, not surprising

[jockm]

I use both BeathBone Black's and Raspberry Pi's each has their tradeoffs. The BeathBone is better suited complex embedded applications. It has more GPIOs, two built in 200Mhz in-order microcontrollers for real time tasks, it is faster (than the pre Pi 2's), etc. Not every application needs to play video. In fact almost every project I have done didn't need video. Most didn't need a UI.

Each has their strengths and their weaknesses. Each has its niche. There is no such thing as better for all uses.

Re:Crap hardware, not surprising

[ArchieBunker]

The Pi was never intended for video playback or a desktop replacement. The main goal was a low cost learning platform.

Military & Industrial Test Suites

[Anonymous Coward]

Military hardware for specific applications is tested for light sensitivity, but it is not a common test.
I have never seen any industrial control equipment subjected to such a test.
Betcha there's gpnna be a whole lot of "unofficial" testing done starting Monday morning, I'll betcha.

Re:Crap hardware, not surprising

[Anonymous Coward]

The SoC in the Pi was designed for digital media players. If that's not intended for video playback, what is?

Re:Crap hardware, not surprising

[itzly]

My impression is that most people are just getting them for cheap ethernet-enabled controllers, not as learning platforms. It doesn't make that great of a learning platform, anyway. Better to get a cheap PC or laptop for that.

Flash Player for Xbox 360

[tepples]

Xenon was the development codename for the Xbox 360 video game console. I was more like: Since when did Adobe port Flash Player to the version of Internet Explorer on Xbox 360? Was it Wii-nus envy to catch up with Nintendo's "Internet Channel powered by Opera"?

Re:Crap hardware, not surprising

[tepples]

And sometimes learning includes watching instructional videos.

Similarly ....

[ankhank]

"Nothing like this will be built again"

I've just had a really amazing experience: a guided tour of the nuclear reactor complex at Torness on the Scottish coast. ... Cameras were verboten -- not because of security, but as an operational precaution. For starters, some embedded controllers in racks in the auxilliary deisel generator control rooms have EPROMs which have been known to be erased by camera flashes in the past, triggering a generator trip ...."

http://www.antipope.org/charli...

Re:Similarly ....

[itzly]

For starters, some embedded controllers in racks in the auxilliary deisel generator control rooms have EPROMs which have been known to be erased by camera flashes in the past

That's why people have always put metal foil stickers on the EPROM window to protect them. Even exposure to sunlight can mess up uncovered EPROMs. And a little sticker seems easier and more reliable than making sure not a single camera makes it through security.

Re:Similarly ....

[ankhank]

Yup.
One would hope they've got a belt-and-suspenders attitude there, as stickers sometimes do dry out and fall off; people sometimes put stickers on wrong; and having one's auxiliary diesel generators fail can be embarassing.

http://sfcitizen.com/blog/wp-c...

Re:Similarly ....

[lars_stefan_axelsson]

That's why people have always put metal foil stickers on the EPROM window to protect them. Even exposure to sunlight can mess up uncovered EPROMs. And a little sticker seems easier and more reliable than making sure not a single camera makes it through security.

Another problem in power generation is that arc fault detectors also has a tendency to be tripped by camera flashes. So keeping cameras out of power plants/transformer sites/etc, is standard operating procedure since time immemorial.

And these EPROMS probably had that black gunk on them that were popular when EPROMS were used in production. Problem is that the gunk had a tendency to dry up and fall off after a couple of decades.

Re: EMI Noisy environments

[SuricouRaven]

Inefficient hardware is sometimes justified by development time.

You can spend many days hand-coding an ideal program for a PIC in ASM. Or you can use an arduino, which takes more power, more space and more money, but can be programmed in a tenth the time by anyone who knows C without needing any esoteric knowledge of harvard architecture and tables of port numbers. If you're doing things a bit more complicated like image processing or networking, the same applies to arduino vs pi: The arduino may be able to do your task if you'll put in the days of programming, but with the pi you're dealing with a familiar linux environment and all the classic libraries are there.

LED acting as a light sensor

[Revek]

I've seen it before back in the day. They are not very efficient but they could cause a critical spike if they are not isolated from a bus.

Re:Crap hardware, not surprising

[ArchieBunker]

How many PCs and laptops have GPIO pins and will run from a microSD card?

Re: EMI Noisy environments

[Anonymous Coward]

It doesn't take much to actually run most CNC setups. That hasn't stopped professional equipment, costing more than thousands of dollars, from having their share of problems and crashing on us or crapping out. More often than not it comes down to user interface stuff or fancy features not used often (I'll do geometry calculations at my desk, not standing in front of the machine) that crap out, but sometimes brings the whole system down. I've seen it even happen when a company rep was demonstrating their new controller for us. At least if we had source code instead of a crappy manual, it would be easier to see ahead of time that a particular controller can choke on a specific combinations of whitespace in the g code, or crazier stuff like splitting a command into two nonsensical ones.

On the other hand, I've seen student RPi projects come through quite often, and we have even few used to monitor equipment, and they just sit there and run 24/7.

Re:Crap hardware, not surprising

[ArchieBunker]

You are missing the point. This is a platform for hardware and software hackers. Somewhere between small microcontrollers (PIC/Atmel) and a PC.

U16 WLCSP package inherently photosensitive

[Anonymous Coward]

The device at U16 on Raspberry Pi 2 v1.1 appears to be an ON Semiconductor NCP6343 DC converter provided in a WLCSP-15 package.

Like all CSP packages, the bare die is photosensitive and needs to be protected from incident light if fault-free operation is expected. Usually such devices are embedded in closed cases like cellphones which prevent light ingress.

However, if the normal operating environment includes uncased bare boards or transparent cases (which are both common and normal for Raspberry Pi), then it is imperative that CSP-packaged dies be protected from light by other means such as opaque epoxies or caps, otherwise such devices cannot be expected to operate within specification.

It is a normal part of the engineer's job to understand their product's operating environment and the components they use, and to design accordingly.

Re:Not Photosensitive

[hankwang]

"A 100mW red laser pointer aimed"

You play around with a HAND-HELD class 3b laser? Still have eyesight in both your eyes? (And your pets/household members)

Legally, those should be operated only by trained staff and I believe they must be equipped with a key lock and interlock connection. That stuff from WickedLasers should really be banned. The laser inside a dvd writer is of similar power, but interlocked and much less dangerous due to the focusing lens.

Re: Claim to fame is important no matter how trivi

[MikeRR]

As first to coin the phrase "xenon death flash" (and do the blutack fix)
it was funny watching the story spread with the phrase intact :)

I am filing this with ...

[niftymitch]

I am blushing and filing this with "gullible is not in the dictionary".

razn1 ~ $ w
  23:14:15 up 11 min, 1 user, load average: 0.00, 0.04, 0.05
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
bob pts/0 whitechrome.wr.t 23:14 7.00s 1.29s 0.04s w
razn1 ~ $
razn1 ~ $
razn1 ~ $ # flash flash flash... must be one honking flash but mine is big.
razn1 ~ $
@razn1 ~ $ w
  23:16:14 up 13 min, 1 user, load average: 0.02, 0.04, 0.05 .....

Had a similar problem many years ago

[ctrl-alt-canc]

I was working to my thesis in nuclear physics, and I was developing a new analytical method based on beam-induced radiation spectrometry. In one of the beam lines we had an alpha particle detector (basically a large Si crystal with a gold-plated surface) that was driving me crazy. When we used the detector for measurements it worked perfectly, but when we turned the beam off and I entered the radiation facility to do some measurements, it was insanely noisy and could not be properly calibrated. I was staring at the screen of the scope looking at the huge noise floor and scratching my head, when at once the noise disappeared, then came back again. This repeated for a few times and suddendly I realized what was happening. The vacuum chamber where the detector was installed had a glass window hidden to my sight that was sometimes used for remote inspection with a TV camera. A technician was doing some maintenance work, walking back and forth in front of the window. When he was close to it the noise disappeared, and when the window glass was clear of obstacles the photoelectric effect in the detector caused the noise! During irradiation tests nobody was inside the facility, so we turned off the lights, and this explained why the detector worked without problems. A piece of duct tape on the glass window fixed the problem for ever, as always...

Re:Had a similar problem many years ago

[Vadim Makarov]

We had a single-photon detector whose electronics contained a little glass-encapsulated Zener diode. That diode was emitting a small quantity of infrared light. When an experiment used more than one detector, they were counting lots of photons from each other's electronics. We have since replaced this Zener diode with a black plastic-encapsulated version, and the problem went away.

Re:Crap hardware, not surprising

[yuhong]

In fact, the Pi2 is better at web browsing than the original.

Poor Design!

[Junior Samples]

This is a simply a case of poor hardware design. The design engineer should have known that exposed silicon is sensitive to light (Remember the glass window EPROMS) and used a packaged version of the regulator.

Xenon Flashes?

[Kizul Emeraldfire]

I must be old. It took me several minutes to realize that neither the title nor the summary for this article were talking about Flash animations that were made by an Internet user who went by the name of Xenon. (His animations were famous-ish on 4Chan for containing copious amounts of ear-rape, among other things.)

It's the UV photons

[BobJacobsen]

Xenon makes a nice flash because it's so white. And it's so white because its emission spectra is so wide, going well into the UV. Some lamps filter the UV out, some don't; there's not enough light in a typical photographic flash for the UV to have any impact. But UV photons are important for upsetting electronics because they have enough energy to pop electrons out of potential wells in silicon/silicon-oxide IC circuits. Visible and IR photons generally don't. Remember the 2708 series of NVROM memories? They had a transparent window that let you erase them with a UV lamp (and a long wait); regular visible light had no effect on them. The visible photons, for any practical flux, just didn't have enough energy.

Re:It's not the light, obviously

[BobJacobsen]

Except that covering one chip with some goop that blocks light fixed it. So it's not EMP. It's the light, probably UV.

Duh, cover off.

[hucker75]

Well stop taking pictures of live electronics with the cover off. Dumbasses. It's hardly going to affect its everyday operation is it?

EMI and computers....

[bjwest]

Maybe this will bring some sanity back into the computer world and put an end to all these windowed cases and caseless computers spewing radiation all over the place. People really have no idea that radiation is detectable and can be deciphered.

Wondering how your neighbor got your banking info? Well, you transmitted it to him...

Re:EMI and computers....

[billstewart]

I've actually seen data from my laptop showing up on a TV. It was out of sync, so it was only part of the screen, repeated multiple times and scrolling slowly. This was back in the 90s, probably a 640x480 screen, and probably the radiation was mostly emitted from the external-video-monitor port (VGA or whatever we used back then.)

UV effect

[cwsumner]

Most IC chips are very sensitive to UV light, thats why the plastic cases are usually black to stop the light.
Every now and then, a manufacturer has some personell who don't know that, and they choose the wrong material for the case.
Usually can fix it by covering with something opaque. Tinfoil works good, as long as you don't short out anything.