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Bug Hardware Hacking

Xenon Flashes Can Make New Raspberry Pi 2 Freeze and Reboot 192

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.
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Xenon Flashes Can Make New Raspberry Pi 2 Freeze and Reboot

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  • by SuricouRaven ( 1897204 ) on Sunday February 08, 2015 @06:48AM (#49009831)

    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.

    • by Anonymous Coward on Sunday February 08, 2015 @07:51AM (#49009943)

      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

      • by Enry ( 630 ) <enry @ w a> on Sunday February 08, 2015 @08:13AM (#49009989) Journal

        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.

        • by Anonymous Coward

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

          • by mgscheue ( 21096 )

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

          • Yep, early motorola and nokia here too.

            • 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 th

              • 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)
                • 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.
          • 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.

            • 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).
          • 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 "

        • 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.

          • by Enry ( 630 )

            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.

            • 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

            • by dougmc ( 70836 )

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

            • 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 inte

        • by Nyder ( 754090 )

          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

        • that still happens with some phone signals in cars today
        • That is a feature. Auto speaker mute when you have a call. :)

      • by Anonymous Coward on Sunday February 08, 2015 @08:28AM (#49010011)

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

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

      • by An dochasac ( 591582 ) on Sunday February 08, 2015 @10:47AM (#49010379)
        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: (Score:2, Informative)

        by 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 feed

      • by Andy Dodd ( 701 )

        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?

    • OMG! (Score:2, Funny)

      by Anonymous Coward

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

  • by Wierdy1024 ( 902573 ) on Sunday February 08, 2015 @06:50AM (#49009835)

    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.

    • by itzly ( 3699663 ) on Sunday February 08, 2015 @06:59AM (#49009849)

      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.

    • by Mal-2 ( 675116 ) on Sunday February 08, 2015 @07:17AM (#49009881) Homepage Journal

      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 [].)

      • by Megane ( 129182 )

        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 t

        • 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.

          • by cdrudge ( 68377 )

            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.

        • 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.

    • by Anonymous Coward on Sunday February 08, 2015 @07:35AM (#49009901)

      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.

  • by thue ( 121682 ) on Sunday February 08, 2015 @07:31AM (#49009897) Homepage

    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.

    • by Anonymous Coward

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

    • by 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.

      • by towermac ( 752159 ) on Sunday February 08, 2015 @10:56AM (#49010427)

        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...

      • Tin foil is easier to solder onto the board.

      • 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 vi

  • That means I can't play Space Quest and Leisure Suit Larry at the same time.

  • by Trax3001BBS ( 2368736 ) on Sunday February 08, 2015 @08:08AM (#49009967) Homepage Journal

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

  • So put it in a case (Score:5, Informative)

    by newsdee ( 629448 ) on Sunday February 08, 2015 @08:49AM (#49010065) Homepage Journal

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

    • Similarly .... (Score:5, Interesting)

      by ankhank ( 756164 ) * on Sunday February 08, 2015 @12:08PM (#49010733) Journal

      "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 ...." []

      • Re:Similarly .... (Score:4, Informative)

        by itzly ( 3699663 ) on Sunday February 08, 2015 @01:28PM (#49011179)

        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.

        • by ankhank ( 756164 ) *

          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.


        • 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.

    • by 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

  • Enough! (Score:5, Funny)

    by Anonymous Coward on Sunday February 08, 2015 @09:13AM (#49010109)

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

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

      • 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"?

  • a de facto EMP / light sensitivity torture test!
    • by newsdee ( 629448 )

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

    • 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.

  • by inflex ( 123318 ) on Sunday February 08, 2015 @10:28AM (#49010293) Homepage Journal

    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 :)

    • by VAXcat ( 674775 )
      "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 z
    • 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! :-)

  • by 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.

  • 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.

  • 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
    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 .....

  • 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 starin
    • 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.
  • 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.

  • 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...

    • 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.)

Make it myself? But I'm a physical organic chemist!