sylvan
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:00 am

simpex wrote:
sylvan wrote:Conclusion: High likelihood U16 is exhibiting optical sensitivity to near infrared.
Possible the intensity of a TV remote IR LED is not strong enough to freeze Raspberry Pi 2.
I'd say likely.

A TV remote IR LED is a minuscule fraction of the intensity of even the weak LASER in a pointer, and in addition is a diffuse source producing a fairly wide angle cone instead of coherent point source, and finally is IR instead of near IR red.

simpex
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:32 am

Both Xenon Lamps and TV Remotes have near infrared spectra.
see: http://www.raspberrypi.org/forums/viewt ... 09#p688609
and http://en.wikipedia.org/wiki/Light-emitting_diode
Far infrared is out of question. It is too distant.
see: http://en.wikipedia.org/wiki/Far_infrared

Secondly, the one who said: "Shining my TV remote directly at U16 had precisely zero effect. So that's a non-issue." ( http://www.raspberrypi.org/forums/viewt ... 58#p688458 ) did not specify the distance between the IR LED and that U16 IC. In his place I would have positioned the IR LED 2-3 mm away from U16 (and other ICs) to get the maximum possible intensity.
Last edited by simpex on Mon Feb 09, 2015 1:34 am, edited 1 time in total.

Lonewolff
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:33 am

Wow, this is an interesting 'feature'. Never heard of that before.

BTW, I just ordered my Pi 2 today :)

Allready have 2 model B's.

I am interested how this Pi 2 Windows 10 release is going to turn out. 8-)
Loving my peice of the Pi

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Lob0426
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 6:23 am

How many of us are going to be taking pictures, shining Lasers or any other bright source, on operating RasPii, now that we know there could be an issue? I am putting mine into a case.

Its like picking at a scab and expecting it not to bleed again!

The Foundation is aware of the "issue" and will look into it.

If I have problem I think the Black electrical tape will be an easy and quick fix.

Sorry @jdb, there will undoubtedly will be even more people that will comment without reading the entire thread! In fact the "Media will be commenting without reading the entire thread, as they usually do!

By tomorrow I expect that the media will have condemned the whole "issue" to bad design or try to create some great parts scandal out of this! :roll:

I am not about to cancel my order so you can all put that question rest right now! :lol:
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 6:26 am

Lonewolff wrote:Wow, this is an interesting 'feature'. Never heard of that before.

BTW, I just ordered my Pi 2 today :)

Allready have 2 model B's.

I am interested how this Pi 2 Windows 10 release is going to turn out. 8-)
It's related to the reason that the Pi NoIR camera works. Silicon electronics is sensitive to near infrared. Since the component in question doesn't have a casing to block incident light, the results are about what one would expect. (The big surprise to me is that there are semiconductor devices--other than those intended to be photosensitive--that aren't encapsulated. I would have thought that simple physical protection would have dictated that.)

OringinalGeek
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 6:57 am

It's been a long time since my field theory classes, but I believe the problem isn't photons. Most digital designers forget about EMI problems. We use "standard" Solutions to solve EMI. One poster talked about his experience with Xenon flashes & how they're triggered. This is the real culprit I suspect. The fast rise time that triggers a multi spectrum signal ( think Fourier Transform). The Raspberry Pi 2 shown is a bare board so it's probably quite susceptible to EMI. Shielding it from light won't help (as the bluetac experiment failure showed). Notice also too that there seems be some distance sensitivity as well. The interference path isn't via conduction through power cord or rails, it's through radiation, not magic photons. I suspect if you used some kind of (grounded) shielding it would make the problem go away. Longer term, the right capacitance on the right signal lines might be the solution.

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manawyrm
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 7:41 am

OringinalGeek wrote:It's been a long time since my field theory classes, but I believe the problem isn't photons.
Please read the thread before posting!

It has been proven to be possible with a strong red laser pointer, too. It is definitly a problem with the photons.
Also: The problem can be fixed with just a little dab of blu-tack.

So long,
Tobias

marked
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 10:02 am

ryang wrote:Might be too opaque. Wondering if maybe some nail polish would be enough?? :D
probably offtopic, but I can see it now -

scene: Standing bewildered at the Boots makeup aisle - surrounded by bright lights and thin expensive plastic containers.

"For your Raspberry Pi 2, did you say sir - Of course sir. My they do grow up quickly, it feels like only yesterday when a bare board was enough - a couple of nice accessories, not like today's teenage temperamentalit, hiding away from the camera. I have a nice Rimmel Black, just right for the discerning board on a gig perhaps? or maybe a nice green for all occasions. It pays to be complementary, doesn't it? You probably might not want the glitter range as that result in a less than desirable match, and you should stay away from LED-setting gel polish... "

<fade to unconciousness .... >

Does it need primer? a base coat? a top coat? one coat or two? can you get away with cheap poundland clearance (l'oreal/rimmel), or do you need to splash out on Clinique or Dior? enquiring minds want to know ...

Does it require an Canon EOS 5D with umbrella shades to get that perfect shot? or Ellen von Unwerth with a Leica or Hasselblad to get that important cover image shot? oh sorry, must have wandered off into fashion photography for some reason...

as an aside, I have to say that using the Colour Search was quite useless in matching the PI2 board.

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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 10:19 am

W. H. Heydt wrote:(The big surprise to me is that there are semiconductor devices--other than those intended to be photosensitive--that aren't encapsulated. I would have thought that simple physical protection would have dictated that.)
Cost.

The epoxy encapsulation will most likely be done by a separate company than the silicon fab, so you need to ship the bare die to them, they package it, and send it on to the next place (e.g., warehouse). That costs. You also need to do more testing to make sure the packaging process hasn't killed any parts due to ESD. More cost. And before you even get to that stage you have to qualify the packaging process to make sure it is compatible with your device. Again, more cost.

So if you plan on selling a part for 30 cents, and the packaging is going to add an extra 10 cents, what do you do? And where, for the majority of your customers, the light sensitivity is not an issue at all as the PCB will be in a box of some sort. It is only customers who ship bare PCBs and who don't know about the light sensitivity of silicon that have problems, but that's an education issue rather than a technology issue.

Neil

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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 10:25 am

OringinalGeek wrote:It's been a long time since my field theory classes, but I believe the problem isn't photons. Most digital designers forget about EMI problems. We use "standard" Solutions to solve EMI. One poster talked about his experience with Xenon flashes & how they're triggered. This is the real culprit I suspect. The fast rise time that triggers a multi spectrum signal ( think Fourier Transform). The Raspberry Pi 2 shown is a bare board so it's probably quite susceptible to EMI. Shielding it from light won't help (as the bluetac experiment failure showed). Notice also too that there seems be some distance sensitivity as well. The interference path isn't via conduction through power cord or rails, it's through radiation, not magic photons. I suspect if you used some kind of (grounded) shielding it would make the problem go away. Longer term, the right capacitance on the right signal lines might be the solution.
The bluetac experiment showed the opposite, that blocking the light cured the problem. Of course the bluetac has to be on the right chip.

dknute
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 10:33 am

Jeez, are there no engineers in this thread? I mean no disrespect to EM testers and other 40-year experience guys but you seem to be more of a theoreticians than anything else.

Problem: Pi2 hangs/reboots when subjected to flash. Possibly also high intensity light in general but apparently only sudden dark-light-dark spikes - not an radio EMP issue.
Cause: U16 chip packaging not adequate for open-case operations.
Solution: Put a blob of black epoxy over U16 and nearby elements.

Pros: Cheap, can be done post-production, even manually if need be. No need for any precision in this operation, if not done well the first time then repeat with more epoxy.
Cons: U16 and capacitors around it cannot be easily desoldered now. IMHO not a big issue, nothing user-servicable here, if it fries it's ususally bye-bye Pi as the unregulated power spike will also fry the the big chip itself. Also, U16 wasn't exactly solder iron friendly to begin with.
Cost: Bottle of epoxy per what, 10k units plus some working hours, nothing unreasonable.

There you go.

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aTao
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 10:35 am

Neil wrote:
W. H. Heydt wrote:(The big surprise to me is that there are semiconductor devices--other than those intended to be photosensitive--that aren't encapsulated. I would have thought that simple physical protection would have dictated that.)
Cost.

Neil
And size and weight.

On another point here.. you wouldnt find me putting (wet) nail varnish anywhere near a circuit board. Not without the standard "try it somewhere that wont matter" first. AFAIK nail varnish uses an acetone base (certainly the remover does), I have no idea what this will do to the varnish protective coating on the board. Should it soften or weaken or remove that layer then you are risking moisture ingress. If it goes further and denatures the epoxy resin that holds the board together.........
>)))'><'(((<

Bikeman
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 11:00 am

OringinalGeek wrote:It's been a long time since my field theory classes, but I believe the problem isn't photons. Most digital designers forget about EMI problems.
[nitpicking] everything EM is photons. Just at different wavelengths/photon energies.[/nitpicking] Sorry couldn't resist.

mmfc
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 11:44 am

aTao wrote: On another point here.. you wouldnt find me putting (wet) nail varnish anywhere near a circuit board. Not without the standard "try it somewhere that wont matter" first. AFAIK nail varnish uses an acetone base (certainly the remover does), I have no idea what this will do to the varnish protective coating on the board. Should it soften or weaken or remove that layer then you are risking moisture ingress. If it goes further and denatures the epoxy resin that holds the board together.........
Epoxy won't be harmed by acetone.

Ravenous
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 11:46 am

marked wrote:
ryang wrote:Might be too opaque. Wondering if maybe some nail polish would be enough?? :D
scene: Standing bewildered at the Boots makeup aisle - surrounded by bright lights and thin expensive plastic containers.

"For your Raspberry Pi 2, did you say sir - Of course sir.
:lol: I used to play a lot of classical guitar - spent a lot of time browsing the shelves in the nailcare section. Boy, did I get some odd looks! ;)

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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 12:34 pm

dknute wrote:Jeez, are there no engineers in this thread? I mean no disrespect to EM testers and other 40-year experience guys but you seem to be more of a theoreticians than anything else.
Yes, if you read the thread it was all really sorted out on page 1 (by a raspbery pi engineer) ... the rest is just chatter.
Solution: Put a blob of black epoxy over U16 and nearby elements.
Maybe, or use a capped part.
Either way the RPi foundation doesn't need to tell us or you anything ahead of time.
In the past components have changed and even board layouts without any announcement.

My main problem is that it causes a *freeze* not a reboot (i.e. doesn't recover) - I'll have to test if the watchdog causes it to reboot.
http://blog.ricardoarturocabral.com/201 ... ng-on.html

Is it a big issue ?
No - but Raspberry Pi's do tend to be run uncased/partially cased a fair amount, judging by internet photos,
and most cases aren't fully light excluding either - mine still triggers with a case on (without blutak fix )
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Die Schatzjaeger
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 12:47 pm

Hello everyone,

I can confirm flashing my Pi2 to Death with a Panasonic Lumix DMC-FZ28.
I tried it three times, two times I had a complete freeze. The third time the Pi restarted.

@mikerr:
Would be very interesting if the Watchdog can handle it. I think the dip down to almost 0V on the 3.3V Rail is the problem.
As far as I know do most CPUs have a Brownout Detection exactly for this kind of Problem.
So:
a) Does the SOC have a Brown Out Detection?
b) What does the Watchdog do?

Right now I'm compiling a Kernel on my Pi2, so I can't test b)

Thomas

vparres
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 12:57 pm

Hi all,

I've tested the RPi 2 flash issue. With an old professional Braun flash, and i was able to reboot or to freeze the Pi, simply by flashing him.
I mean, with half of the flash power, my RPi just freeze, no matter if i flash top or bottom of the PCB, but with the full power, my RPi just reboot, completely, but only if i flash the top face of the PCB.

This bug is not really embarrassing, especially in normal use. If you are using you Pi with a Xeon Flash, just cover him.

Thats All. I hope i helped someone.

Ravenous
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:20 pm

So has anyone said it yet... Is the raspi compatible with Flash? (Sorry.)

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RaTTuS
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:27 pm

How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

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rahlquist
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:52 pm

Lob0426 wrote:How many of us are going to be taking pictures, shining Lasers or any other bright source, on operating RasPii, now that we know there could be an issue? I am putting mine into a case.
You make valid points but I believe everyone is just trying to make sure its figured out and everyone wants to contribute. A case may fix 99% of issues but most of us like better than 99% reliability if we can manage it I am sure. In my case the primary use for some of my Pi is in part as IP cameras. Some of the cameras do face roadways and I need to know that some person with 2M candlepower Xenon headlamps, light bars, whatever is not going to catch my Pi and poke it in the eye on the way by. ;)

So, yes, for a lot of us who dwell in an evil lair, poorly lit, with no bright corona or xenon or laser discharge it's a non starter of an issue ;) For others we just want to understand and fix, to prevent the 1% random error from this item.
aTao wrote:On another point here.. you wouldnt find me putting (wet) nail varnish anywhere near a circuit board. Not without the standard "try it somewhere that wont matter" first. AFAIK nail varnish uses an acetone base (certainly the remover does), I have no idea what this will do to the varnish protective coating on the board. Should it soften or weaken or remove that layer then you are risking moisture ingress. If it goes further and denatures the epoxy resin that holds the board together.........
Not to mention what the acetone may do to the actual ic package itself, such as it is. That's why I recommended the Sugru. I don't have any on hand at the moment though to test and its a bit expensive to buy here in the states. The other reason I suggested Sugru is it is also good to 180 °C, nail polish I am sure doesn't have that going for it. If anyone isnt familiar with the stuff here is a datasheet https://sugru.com/pdfs/tds.pdf

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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 1:57 pm

Coloured silicone gloop might do the trip. No temperature issues, inert. although some are acetone based IIRC.

Wwafers are cleaned with some pretty heavy duty solvents, so I don't think acetone would be a problem on the component itself.
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simpex
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 2:08 pm

"Other bright lights – even camera flashes using other technologies – won’t set it off. You can take your naked Pi 2 in the sunshine for a picnic or take it to a rave, and it’ll be perfectly solid."
Source: http://www.raspberrypi.org/xenon-death- ... cs-lesson/
I am not fully convinced that bright sunlight is harmless to Raspberry Pi 2 as long as, not having enough sun in UK this time of the year, there was no way to test the development board regarding its sensitivity to sunlight.

More tests (with all kind of light sources) done by various people, who bought Raspberry Pi 2 boards, are needed. Most non conductive materials are transparent to the infrared radiation and in consequence various home made IR screens (fixes) applied on that U16 IC might not work well.
Last edited by simpex on Mon Feb 09, 2015 2:22 pm, edited 1 time in total.

jamesh
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 2:16 pm

simpex wrote:"Other bright lights – even camera flashes using other technologies – won’t set it off. You can take your naked Pi 2 in the sunshine for a picnic or take it to a rave, and it’ll be perfectly solid."
Source: http://www.raspberrypi.org/xenon-death- ... cs-lesson/
I am not fully convinced that bright sunlight is harmless to Raspberry Pi 2 as long as, not having enough sun in UK this time of the year, there was no way to test the development board regarding its sensitivity to sunlight.
The sun is VERY bright in Cambridge at the moment...
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Ravenous
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Re: Why is the PI2 camera-shy ?

Mon Feb 09, 2015 2:24 pm

Trivia question: is it a flash (ie a brief transient) or can a constant but very high intensity light cause this? I'm thinking of the step response in the control circuits of the regulator chip - will it be stable under a sustained light level? If so, sunlight is less likely to be a serious problem.

(Just a thought. Not that it matters much to most of us.)

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