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A Xenon flash will cause the Raspberry Pi 2 to freeze

raspberrypi.org

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Re: A Xenon flash will cause the Raspberry Pi 2 to freeze

#121

Post by AlyssaRowan »

DonHopkins wrote: post #114
AlyssaRowan wrote: post #109

Earlier quoted context omitted.

Handy tip! Which - just tested - seems to work for me, at least with a couple of coats of black nail polish, and double-checked with a high-end Canon flash and a random green laser pointer. (Of course your mileage, and nail polish, may vary.) I should change the hostname to nemi. ;) There's another 'shiny' chip on the board too, next to the HDMI port, U8 I think, but it doesn't seem to give a damn what you do to that…

Don't you get on the NSA's subversive person list for buying black nail polish?

If it were that easy, all the cool kids would be doing it.

Re: A Xenon flash will cause the Raspberry Pi 2 to freeze

#122

Post by rasz_pl »

poizan42 wrote: post #105
Animats wrote: post #77

Earlier quoted context omitted.

OK, that part is a reject. It will probably crash in bright sunlight, too.

Apparently the U16 IC is completely missing its casing

its not missing it, its just a specific packaging type (flip chip). Its supposed to be used in products with full enclosure, or under a heatsink.

For example almost every single CPU and GPU nowadays uses some fcbga packaging (flip chip on ceramic/pcb carrier), but they are all hidden under heatsinks and often additional heat spreaders.

http://www.maximintegrated.com/en/app-notes/index.mvp/id/400...

Re: A Xenon flash will cause the Raspberry Pi 2 to freeze

#124

Post by yock »

ridgeguy wrote: post #75
jarvist wrote: post #39

Earlier quoted context omitted.

A xenon tube is not a spark gap, in terms of the early radio receiver 'spark gaps' which were a primitive tuned circuit used to then feed an antenna (it wasn't the spark itself that was used for the transmission). Sparks produce a broadband radio signal, that decays strongly with increasing frequency. Very little is present in the Megahertz region, which is why lightening doesn't interfere with FM radio that much. Ra…

I think the reason lightning doesn't perturb FM transmissions much is that lightning, being a source of additional energy in the receiver's passband, is an amplitude modulation interference source, whereas FM transmits its information by Frequency Modulation, which is nominally insensitive to AM EMI sources. Any amateur radio operator in the Midwest or Florida using AM on 144MHz will tell you that lightning for sure…

FM receivers have a limiter circuit, which cuts off any source of amplitude change from the original signal. I'm studying to become a ham right now, and this bit is fresh in my mind.

Re: A Xenon flash will cause the Raspberry Pi 2 to freeze

#126

Post by djmips »

lotsofmangos wrote: post #63
foobarbecue wrote: post #44

Earlier quoted context omitted.

"When they get that short they are basically becoming infra-red anyway." You mean UV. You got your spectrum backwards. You should probably just admit your error here -- it's light, not radio waves, causing the effect. Sure, they're part of a common spectrum, but your statement "radio waves are light" is obviously false. It's a bit like saying "red is blue". Edit: I misread the above, lotsofmangos was talking about wa…

I have been saying all along that it is electromagnetic waves in the visible or near visible spectrum causing the effect, otherwise the bluetack would not work. As to saying that radio is light, if calculating the propagation speed of a radio wave, you don't talk about its speed of radio, you talk about its speed of light. In many technical contexts, light is one of the default terms. Also, there would be no need for…

Agree, not sure why you were downvoted. EMP is photons. They were already considering the non visible spectrum when talking UV. There's a real prejudice and ignorance regarding visible light versus the entire electromagnetic spectrum.

Re: A Xenon flash will cause the Raspberry Pi 2 to freeze

#128

Post by IgorPartola »

agumonkey wrote: post #98

The new wave of single board computers really exposed me to the amount of failure that can happen at the electrical level. Growing up with large ATX boxes I'd never expect so many things to go wrong. btw: anyone tried to light-freeze other devices (banana, orange, cubie, etc) ?

As my electronics professor said: "every digital circuit is really an analog circuit."

Re: A Xenon flash will cause the Raspberry Pi 2 to freeze

#130

Post by Narishma »

seba_dos1 wrote: post #113
Narishma wrote: post #106

Earlier quoted context omitted.

That's because completely free means different things to different people. Does it include the firmware/bios? Are you only concerned with what runs on the CPU?

Original Raspberry Pi needs user to provide non-free firmware blobs on SD card to even boot the CPU. That's pretty non-free in any meaning I can imagine. It seems like it's still the case with Raspberry Pi 2.

The only difference between that an a PC is that the PC stores the firmware blob in a ROM chip while the Pi stores it on the SD card. Both require it to boot.
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