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Xenon Flashes Can Make New Raspberry Pi 2 Freeze and Reboot

Posted by timothy on from the camera-shy dept.

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.

23 of 192 comments (clear)

  1. Maybe not the power supply? by Wierdy1024 · · Score: 3, Insightful

    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.

    1. Re:Maybe not the power supply? by itzly · · Score: 5, Informative

      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.

    2. Re:Maybe not the power supply? by Mal-2 · · Score: 4, Informative

      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.)

      --
      How is the Riemann zeta function like Trump rallies? Both have an endless number of trivial zeros.
    3. Re:Maybe not the power supply? by Anonymous Coward · · Score: 4, Informative

      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.

  2. Bring out the tinfoil by thue · · Score: 5, Funny

    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.

    1. Re:Bring out the tinfoil by towermac · · Score: 4, Funny

      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...

  3. The new power supplies may be sensitve to EMP by Anonymous Coward · · Score: 5, Interesting

    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

    1. Re:The new power supplies may be sensitve to EMP by Enry · · Score: 3, Interesting

      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.

    2. Re:The new power supplies may be sensitve to EMP by Anonymous Coward · · Score: 5, Insightful

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

    3. Re:The new power supplies may be sensitve to EMP by An+dochasac · · Score: 4, Interesting

      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.

    4. Re:The new power supplies may be sensitve to EMP by wolrahnaes · · Score: 5, Informative

      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.

      --
      I used to get high on life, but I developed a tolerance. Now I need something stronger.
    5. Re:The new power supplies may be sensitve to EMP by bemymonkey · · Score: 3, Informative

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

  4. Re:Not Photosensitive by Anonymous Coward · · Score: 5, Informative

    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.

  5. Claim to fame is important no matter how trivial.. by Trax3001BBS · · Score: 4, Insightful

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

  6. Re:Not Photosensitive by Anonymous Coward · · Score: 4, Informative

    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.

  7. So put it in a case by newsdee · · Score: 5, Informative

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

    --
    The ENIAC Demo Competition
  8. Enough! by Anonymous Coward · · Score: 5, Funny

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

  9. Nothing unusual really by inflex · · Score: 4, Informative

    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 :)

  10. Re:Crap hardware, not surprising by thegarbz · · Score: 4, Insightful

    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.

  11. Re:Crap hardware, not surprising by jockm · · Score: 3, Insightful

    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.

    --

    What do you know I wrote a novel
  12. Similarly .... by ankhank · · Score: 4, Interesting

    "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...

    1. Re:Similarly .... by itzly · · Score: 3, Informative

      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.

  13. Re: EMI Noisy environments by SuricouRaven · · Score: 4, Insightful

    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.