9 ms·

The Xenon Death Flash: How a Camera Nearly Killed the Raspberry Pi 2

233 points by DamonHD 1y ago

pvg 1y ago
HN thread at the time https://news.ycombinator.com/item?id=9015663 https://news.ycombinator.com/item?id=9015663
- DamonHD 1y ago
  Thank you!
Mobil1 1y ago
[dead]
xeonmc 1y ago
The intensity threshold was crucial. Regular LED camera flashes didn’t produce enough photons, but xenon flashes and laser pointers packed sufficient punch to trigger the malfunction. Even more interesting, the effect required silicon’s specific bandgap energy—meaning infrared and visible light could potentially cause problems, but only at extreme intensities. Article is confusing intensity with wavelength. Unless they’re talking about nonlinear multiphoton absorption which could inly be achieved by intense ultrafast laser pulses
- goda90 1y ago
  How so? It sounds like they are saying high intensity light with wavelengths in the infrared and visible affect the chip, suggesting higher and lower wavelengths don't even with high intensity.
rini17 1y ago
I had same issue with fancy translucent cover for my hearing aids. Sunlight at certain angles and flashes caused noise. Nobody believed me.
nickdothutton 1y ago
Reminds me just a little of the "SPARC CPU cache corruption by radioactive decay of impurities in chip packaging" which cost me many hours in my first job.
- robocat 1y ago
  IBM memory chips - great story, which I copied into this comment: https://news.ycombinator.com/item?id=25279964 https://news.ycombinator.com/item?id=25279964
Sharlin 1y ago
Another classic hardware glitch: iPhones Are Allergic to Helium [1] [1] https://www.ifixit.com/News/11986/iphones-are-allergic-to-helium https://www.ifixit.com/News/11986/iphones-are-allergic-to-he...
- K0balt 1y ago
  This one was actually pretty cool, since the effect of alternative environmental gasses had not been extensively documented by MEMS device manufacturers at that time. It was interesting and remarkable because many engineers, despite solid diligence, might have missed the possibility unless they were well versed in MEMS manufacturing processes which were not very widely known before publication. Still, it wasn’t at all surprising to the manufacturers of the parts, since using a calibrated gas mixture for initial adjustment is a standard design step.
  - stinkbeetle 1y ago
    It was documented in Apple's user guide.
    - K0balt 1y ago
      Really? If that happened before the publicised discovery, it is a very impressive example of attention to detail.
      - stinkbeetle 1y ago
        > Really? Really. It's in the article linked. > If that happened before the publicised discovery, it is a very impressive example of attention to detail. The article seems to imply it was, but I don't know timelines because links are broken and I don't feel like doing archaeology. It is a known issue with that MEMS component before it made its way into the iPhone, so I don't find it very impressive. I don't know about Apple in particular, but it is very standard for electronics user manuals and spec sheets to list operating envelopes and known issues and limitations exhaustively.
- 1y ago
K0balt 1y ago
Photosensitivity in WLCSP parts is not something that was “discovered” by the community. The data sheets for WLCSP parts specify that the part is photosensitive and often give data on how light can affect the part. This has been known since the inception of WLCSP, and is treated as a design parameter by responsible engineers. Chip manufacturers know that bare silicon chips are light sensitive, they are literally made of thousands/millions/billions of tiny solar panel junctions. CMOS imaging tech evolved from exposing cmos memory chips to a focused image. WLCSP chips are basically unpackaged silicon chips. None of this is a “discovery”. People have been decapoing transistors to use them as photodetectors or solar cells since people started putting metal covers on transistors to protect them from light interference. Early photo transistors were a standard npn part with a windowed can. If you put WLCSP parts on a PCB that will be unprotected, and photosensitivity is not an acceptable design feature, you are either a hack, or making mistakes like a NOOB and should be supervised by a senior engineer. It’s called reading the data sheet, before integrating a part into millions of devices. Maybe understanding what a silicon chip is made of and how semiconductor junctions work. It’s a basic engineering responsibility, and failing to do so is an abdication of your duties and responsibilities as an engineer. Anyway, cool story except I get the definite feel that the article was written or heavily influenced by LLM output, by the pedantic cadence and constant summarization.
- Maxious 1y ago
  We played this monday morning quarterbacking 10 years ago, the datasheet Raspberry Pi used said: > Light-sensitive circuit protection, as claimed in literatures, is not a reality concern since silicon is only transparent to long wavelength light, which is rarely encountered in broad applications of WLCSP. https://web.archive.org/web/20150210111428/https://www.fairchildsemi.com/application-notes/AN/AN-5075.pdf https://web.archive.org/web/20150210111428/https://www.fairc...
  - K0balt 1y ago
    Well then, can’t really fault the engineers if they told users about it. Fun hobby mystery and nobody got killed. 10/10.
- 1y ago
tallanvor 1y ago
I can't find a link now, but I remember a story about AT&T (I think) proudly showing off their new digital switching technology recently installed at an exchange and having the system crash when the flashes were strong enough to erase the EEPROMs they used in the system.
- DamonHD 1y ago
  Erasing an EPROM typically took ~20 minutes of fairly intense UV, so that seems unlikely as-is.
  - lambda 1y ago
    The amount of exposure to reliably fully erase it, and the amount to flip one bit, are likely different. Flip the wrong bit and you can easily cause a crash. Yes, if you wanted to be sure to clear every bit you'd need that 20 minutes of exposure, but I wouldn't be surprised if flipping a single bit or a few of them was much easier.
    - anonymousiam 1y ago
      Two different effects being confused here. The EPROMs had a transparent window to the whole die. Bright flashes of light could disrupt the normal reading of memory, without permanently changing it. The sticker covering the window (usually with a description and version of the firmware) served multiple purposes.
      - DamonHD 1y ago
        Transient disruption of normal reads seems plausible to me. Any sort of erasure by flashes of light (visible or UV) that did not injure the humans, much less so!
- sidewndr46 1y ago
  The story as told is definitely made up as you can't erase an EEPROM with UV light. It's electrically erasable. If you meant 'EPROM' the story is almost certainly made up as the same company that sold you the EPROM sold you the sticker to put over the window.
geerlingguy 1y ago
Every even numbered Pi model had some kind of interesting quirk requiring a hardware change to 'fix': - Pi 2 had the camera flash reboot issue - Pi 4 had improperly implemented USB-C charging circuit, causing many PD adapters to not power it[1] (I still have and use both of the original models — the hardware flaw was only a problem in certain circumstances.) The Pi 5 has it's funky 5V / 5A requirement (though 5V / 3A works fine if you're not using high power USB accessories, if you have a decent power adapter), but it's otherwise not had any hardware-level odd quirk on the scale of Pi 2/4. So the question is: what will it be on the Pi 6? [1] https://hackaday.com/2019/07/16/exploring-the-raspberry-pi-4-usb-c-issue-in-depth/ https://hackaday.com/2019/07/16/exploring-the-raspberry-pi-4...
- klysm 1y ago
  Have the compute modules had similar problems?
  - geerlingguy 1y ago
    They never made a CM2, but since they release the CMs after the main model B launch, they've always had time to fix a couple little hardware issues by the time the CM comes out.
- DamonHD 1y ago
  Come on: "every" is clickbait and not meaningful here. My huge respect for you took a little knock.
  - skrebbel 1y ago
    How can an HN comment be clickbait? It's just fun nerdy banter. Obviously "both" is the better word choice here but then GP couldn't make the joke about number 6 could he?
    - DamonHD 1y ago
      It's an overhyped style which I suspect we get trained in when writing for payment. I've tried explicitly to avoid it, but usually the subs will rewrite all headings. Jeff shouldn't be doing it here: there is no sub to blame and we're not a mouth-breathing audience...
itishappy 1y ago
Fun fact: semiconductor effects are often reversible! A light emitting diode is an inefficient photovoltaic panel, and vice versa. This is relevant here because the same effect that allows you to stimulate the junctions using high intensity IR light happens in reverse: a stimulated junction emits IR light which can be detected through a thin enough package. With the right camera you could in theory take a video of specific junctions activating on chip. Efficiency makes this difficult in practice. I don't know how many photons you get per junction per clock cycle but it's not many, and those photons still need to make their way out of the package and be picked up by your sensor. I suspect getting a useful signal involves seriously overvolting the chip and/or underclocking it, so I'm not sure how "functional" of a test it would be. Wish I could remember the name of the company that was working on commercializing this...
- diggan 1y ago
  > Fun fact: semiconductor effects are often reversible! A light emitting diode is an inefficient photovoltaic panel, and vice versa Another fun example: Manually rotating a DC motor produces current! Might make sense if you start out with generators I suppose, but as someone who used a DC motor "the other way" first, it was kind of counter-intuitive.
  - ryoshu 1y ago
    A speaker is an inefficient microphone and vice-versa.
    - oskarkk 1y ago
      I once connected a microphone to the audio output by mistake. You can imagine how confused I was when the microphone started playing music.
  - itishappy 1y ago
    Examples off the top of my head include: * Electromagnetism (motors/generators) * Photoelectricity (LEDs/PVs) * Thermoelectricity (TEGs/Peltier coolers) * Piezoelectricity (crystal oscillators) Anybody got others?
skrebbel 1y ago
In case the author reads HN, I just wanted to share that I was rather irked by the writing style, the way it adds all kinds of weird irrelevant bits of info that don't actually clarify anything (eg "the same phenomenon Einstein won a Nobel Prize for explaining") and ways to make things sound more spectacular than they are (eg "Blu-Tack (yes, really)" or the whole story about "community trust"). I read on your about page that you use LLMs to assist your writing. Consider this comment a suggestion to depend on them less, or at least be more critical with their output. I've never been so frustrated reading a blog post as when I read yours as I flashed from interest to annoyance and back again many times.
- gedy 1y ago
  I do agree that "assisted writing" is going to get old fast. Though your comment did made me think of as an alterative to chatting with LLMs, AI could be used to present search results on a particular topic in whatever format you prefer. E.g. these breezy writeups, tiktok style clips, youtube, podcast, "just the facts", etc. Different strokes and all that. As long as it's clear it's the machine or UI, I don't mind LLM output that much.
  - KennyBlanken 1y ago
    If I want to read LLM output, I'll type some input into one. I don't come to HN to get linked to shitty slightly-massaged LLM crap.
- yuliyp 1y ago
  To contrast, I found that tidbit about Einstein helpful, as it took my memory more promptly to when I studied it in physics classes. I enjoyed the post more as a story more than as a report.
- nssnsjsjsjs 1y ago
  Hard disagree. I enjoyed reading every word.
- Xelynega 1y ago
  One of the things I'm not looking forward to with people "just throwing it through an LLM for a final pass" is the loss of individual voice. Everything is starting to sound the same, and it's becoming monotonous
tedunangst 1y ago
Conclusion seems rather forced. Like if trends continue, in ten years you will 1024 babies.
jdbs_alter_ego 1y ago
Ugh, this article smells of AI slop. For starters the "jdb" "forum user" (with a Raspberry Pi Engineer tag - i.e. an employee) never claimed to have tested the board with any sort of Samsung camera. The actual post referencing Samsung is here: https://forums.raspberrypi.com/viewtopic.php?f=28&t=99042#p687844 https://forums.raspberrypi.com/viewtopic.php?f=28&t=99042#p6... - which has a couple of broken nested quotes. And literally the next post has jdb's replication with a Canon compact handheld.
- mmastrac 1y ago
  The author appears to have some LLM styles in other posts on the site (bolded list headers are the dead giveaway IMO): https://magnus919.com/2025/05/what-i-learned-about-agi-at-a-nyc-meetup-and-why-were-not-ready/ https://magnus919.com/2025/05/what-i-learned-about-agi-at-a-...
RajT88 1y ago
I am reminded of a strange issue I had with a DV Cam which I took on a "tiger cruise". The TC is where you visit your family aboard an aircraft carrier on the way back from a tour - in our case we rode the boat from Honolulu to San Diego. When on deck, the video would get scrambled every 3 seconds. It was a weird issue! I soon figured out it lined up with the sweep of the radar array - makes sense. Knowing I was dealing with radiation of some sort, I reasoned if I kept my phone angled so the battery (filled with heavy metals) between the radar array and magnetic heads, the video would no longer stutter every 3 seconds. Worked like a charm.
pclmulqdq 1y ago
Post-silicon debug of flip-chip parts is sometimes done by shining a laser on the chip at a very specific spot and detecting backscatter from the laser spot to determine if a transistor is on or not. If you turn the laser power up, you can switch specific transistors open or closed. Semiconductors in general are pretty sensitive to light, which is why they are usually packaged in a way that keeps them dark during operation.
prpl 1y ago
I used to use xenon flashes to calibrate latencies to calibrate data streams. I had a few different SDR devices hooked up to consumer hardware, and a high resolution/accuracy (50ns) time device I could control a xenon flash with. I’d trigger the xenon flash and basically just inject the flash in the data.
johnea 1y ago
This also happened to me. I guess it was the late 1980s. I was programming UV erasable microcontrollers in quartz-windowed ceramic packages. Once I had the whole multi-processor distributed system up and running, I snapped a photo with my flash (film) sports camera. Everything crashed! I also had to repeat the process reliably a couple of times before I was convinced it was the flash that caused it.

233 points by DamonHD 1y ago

pvg 1y ago

HN thread at the time https://news.ycombinator.com/item?id=9015663 https://news.ycombinator.com/item?id=9015663

DamonHD 1y ago
Thank you!

Mobil1 1y ago

[dead]

xeonmc 1y ago

The intensity threshold was crucial. Regular LED camera flashes didn’t produce enough photons, but xenon flashes and laser pointers packed sufficient punch to trigger the malfunction. Even more interesting, the effect required silicon’s specific bandgap energy—meaning infrared and visible light could potentially cause problems, but only at extreme intensities. Article is confusing intensity with wavelength. Unless they’re talking about nonlinear multiphoton absorption which could inly be achieved by intense ultrafast laser pulses

goda90 1y ago
How so? It sounds like they are saying high intensity light with wavelengths in the infrared and visible affect the chip, suggesting higher and lower wavelengths don't even with high intensity.

rini17 1y ago

I had same issue with fancy translucent cover for my hearing aids. Sunlight at certain angles and flashes caused noise. Nobody believed me.

nickdothutton 1y ago

Reminds me just a little of the "SPARC CPU cache corruption by radioactive decay of impurities in chip packaging" which cost me many hours in my first job.

robocat 1y ago
IBM memory chips - great story, which I copied into this comment: https://news.ycombinator.com/item?id=25279964 https://news.ycombinator.com/item?id=25279964

Sharlin 1y ago

Another classic hardware glitch: iPhones Are Allergic to Helium [1] [1] https://www.ifixit.com/News/11986/iphones-are-allergic-to-helium https://www.ifixit.com/News/11986/iphones-are-allergic-to-he...

K0balt 1y ago
This one was actually pretty cool, since the effect of alternative environmental gasses had not been extensively documented by MEMS device manufacturers at that time. It was interesting and remarkable because many engineers, despite solid diligence, might have missed the possibility unless they were well versed in MEMS manufacturing processes which were not very widely known before publication. Still, it wasn’t at all surprising to the manufacturers of the parts, since using a calibrated gas mixture for initial adjustment is a standard design step.
- stinkbeetle 1y ago
  It was documented in Apple's user guide.
  - K0balt 1y ago
    Really? If that happened before the publicised discovery, it is a very impressive example of attention to detail.
    - stinkbeetle 1y ago
      > Really? Really. It's in the article linked. > If that happened before the publicised discovery, it is a very impressive example of attention to detail. The article seems to imply it was, but I don't know timelines because links are broken and I don't feel like doing archaeology. It is a known issue with that MEMS component before it made its way into the iPhone, so I don't find it very impressive. I don't know about Apple in particular, but it is very standard for electronics user manuals and spec sheets to list operating envelopes and known issues and limitations exhaustively.
1y ago

K0balt 1y ago

Photosensitivity in WLCSP parts is not something that was “discovered” by the community. The data sheets for WLCSP parts specify that the part is photosensitive and often give data on how light can affect the part. This has been known since the inception of WLCSP, and is treated as a design parameter by responsible engineers. Chip manufacturers know that bare silicon chips are light sensitive, they are literally made of thousands/millions/billions of tiny solar panel junctions. CMOS imaging tech evolved from exposing cmos memory chips to a focused image. WLCSP chips are basically unpackaged silicon chips. None of this is a “discovery”. People have been decapoing transistors to use them as photodetectors or solar cells since people started putting metal covers on transistors to protect them from light interference. Early photo transistors were a standard npn part with a windowed can. If you put WLCSP parts on a PCB that will be unprotected, and photosensitivity is not an acceptable design feature, you are either a hack, or making mistakes like a NOOB and should be supervised by a senior engineer. It’s called reading the data sheet, before integrating a part into millions of devices. Maybe understanding what a silicon chip is made of and how semiconductor junctions work. It’s a basic engineering responsibility, and failing to do so is an abdication of your duties and responsibilities as an engineer. Anyway, cool story except I get the definite feel that the article was written or heavily influenced by LLM output, by the pedantic cadence and constant summarization.

Maxious 1y ago
We played this monday morning quarterbacking 10 years ago, the datasheet Raspberry Pi used said: > Light-sensitive circuit protection, as claimed in literatures, is not a reality concern since silicon is only transparent to long wavelength light, which is rarely encountered in broad applications of WLCSP. https://web.archive.org/web/20150210111428/https://www.fairchildsemi.com/application-notes/AN/AN-5075.pdf https://web.archive.org/web/20150210111428/https://www.fairc...
- K0balt 1y ago
  Well then, can’t really fault the engineers if they told users about it. Fun hobby mystery and nobody got killed. 10/10.
1y ago

tallanvor 1y ago

I can't find a link now, but I remember a story about AT&T (I think) proudly showing off their new digital switching technology recently installed at an exchange and having the system crash when the flashes were strong enough to erase the EEPROMs they used in the system.

DamonHD 1y ago
Erasing an EPROM typically took ~20 minutes of fairly intense UV, so that seems unlikely as-is.
- lambda 1y ago
  The amount of exposure to reliably fully erase it, and the amount to flip one bit, are likely different. Flip the wrong bit and you can easily cause a crash. Yes, if you wanted to be sure to clear every bit you'd need that 20 minutes of exposure, but I wouldn't be surprised if flipping a single bit or a few of them was much easier.
  - anonymousiam 1y ago
    Two different effects being confused here. The EPROMs had a transparent window to the whole die. Bright flashes of light could disrupt the normal reading of memory, without permanently changing it. The sticker covering the window (usually with a description and version of the firmware) served multiple purposes.
    - DamonHD 1y ago
      Transient disruption of normal reads seems plausible to me. Any sort of erasure by flashes of light (visible or UV) that did not injure the humans, much less so!
sidewndr46 1y ago
The story as told is definitely made up as you can't erase an EEPROM with UV light. It's electrically erasable. If you meant 'EPROM' the story is almost certainly made up as the same company that sold you the EPROM sold you the sticker to put over the window.

geerlingguy 1y ago

Every even numbered Pi model had some kind of interesting quirk requiring a hardware change to 'fix': - Pi 2 had the camera flash reboot issue - Pi 4 had improperly implemented USB-C charging circuit, causing many PD adapters to not power it[1] (I still have and use both of the original models — the hardware flaw was only a problem in certain circumstances.) The Pi 5 has it's funky 5V / 5A requirement (though 5V / 3A works fine if you're not using high power USB accessories, if you have a decent power adapter), but it's otherwise not had any hardware-level odd quirk on the scale of Pi 2/4. So the question is: what will it be on the Pi 6? [1] https://hackaday.com/2019/07/16/exploring-the-raspberry-pi-4-usb-c-issue-in-depth/ https://hackaday.com/2019/07/16/exploring-the-raspberry-pi-4...

klysm 1y ago
Have the compute modules had similar problems?
- geerlingguy 1y ago
  They never made a CM2, but since they release the CMs after the main model B launch, they've always had time to fix a couple little hardware issues by the time the CM comes out.
DamonHD 1y ago
Come on: "every" is clickbait and not meaningful here. My huge respect for you took a little knock.
- skrebbel 1y ago
  How can an HN comment be clickbait? It's just fun nerdy banter. Obviously "both" is the better word choice here but then GP couldn't make the joke about number 6 could he?
  - DamonHD 1y ago
    It's an overhyped style which I suspect we get trained in when writing for payment. I've tried explicitly to avoid it, but usually the subs will rewrite all headings. Jeff shouldn't be doing it here: there is no sub to blame and we're not a mouth-breathing audience...

itishappy 1y ago

Fun fact: semiconductor effects are often reversible! A light emitting diode is an inefficient photovoltaic panel, and vice versa. This is relevant here because the same effect that allows you to stimulate the junctions using high intensity IR light happens in reverse: a stimulated junction emits IR light which can be detected through a thin enough package. With the right camera you could in theory take a video of specific junctions activating on chip. Efficiency makes this difficult in practice. I don't know how many photons you get per junction per clock cycle but it's not many, and those photons still need to make their way out of the package and be picked up by your sensor. I suspect getting a useful signal involves seriously overvolting the chip and/or underclocking it, so I'm not sure how "functional" of a test it would be. Wish I could remember the name of the company that was working on commercializing this...

diggan 1y ago
> Fun fact: semiconductor effects are often reversible! A light emitting diode is an inefficient photovoltaic panel, and vice versa Another fun example: Manually rotating a DC motor produces current! Might make sense if you start out with generators I suppose, but as someone who used a DC motor "the other way" first, it was kind of counter-intuitive.
- ryoshu 1y ago
  A speaker is an inefficient microphone and vice-versa.
  - oskarkk 1y ago
    I once connected a microphone to the audio output by mistake. You can imagine how confused I was when the microphone started playing music.
- itishappy 1y ago
  Examples off the top of my head include: * Electromagnetism (motors/generators) * Photoelectricity (LEDs/PVs) * Thermoelectricity (TEGs/Peltier coolers) * Piezoelectricity (crystal oscillators) Anybody got others?

skrebbel 1y ago

In case the author reads HN, I just wanted to share that I was rather irked by the writing style, the way it adds all kinds of weird irrelevant bits of info that don't actually clarify anything (eg "the same phenomenon Einstein won a Nobel Prize for explaining") and ways to make things sound more spectacular than they are (eg "Blu-Tack (yes, really)" or the whole story about "community trust"). I read on your about page that you use LLMs to assist your writing. Consider this comment a suggestion to depend on them less, or at least be more critical with their output. I've never been so frustrated reading a blog post as when I read yours as I flashed from interest to annoyance and back again many times.

gedy 1y ago
I do agree that "assisted writing" is going to get old fast. Though your comment did made me think of as an alterative to chatting with LLMs, AI could be used to present search results on a particular topic in whatever format you prefer. E.g. these breezy writeups, tiktok style clips, youtube, podcast, "just the facts", etc. Different strokes and all that. As long as it's clear it's the machine or UI, I don't mind LLM output that much.
- KennyBlanken 1y ago
  If I want to read LLM output, I'll type some input into one. I don't come to HN to get linked to shitty slightly-massaged LLM crap.
yuliyp 1y ago
To contrast, I found that tidbit about Einstein helpful, as it took my memory more promptly to when I studied it in physics classes. I enjoyed the post more as a story more than as a report.
nssnsjsjsjs 1y ago
Hard disagree. I enjoyed reading every word.
Xelynega 1y ago
One of the things I'm not looking forward to with people "just throwing it through an LLM for a final pass" is the loss of individual voice. Everything is starting to sound the same, and it's becoming monotonous

tedunangst 1y ago

Conclusion seems rather forced. Like if trends continue, in ten years you will 1024 babies.

jdbs_alter_ego 1y ago

Ugh, this article smells of AI slop. For starters the "jdb" "forum user" (with a Raspberry Pi Engineer tag - i.e. an employee) never claimed to have tested the board with any sort of Samsung camera. The actual post referencing Samsung is here: https://forums.raspberrypi.com/viewtopic.php?f=28&t=99042#p687844 https://forums.raspberrypi.com/viewtopic.php?f=28&t=99042#p6... - which has a couple of broken nested quotes. And literally the next post has jdb's replication with a Canon compact handheld.

mmastrac 1y ago
The author appears to have some LLM styles in other posts on the site (bolded list headers are the dead giveaway IMO): https://magnus919.com/2025/05/what-i-learned-about-agi-at-a-nyc-meetup-and-why-were-not-ready/ https://magnus919.com/2025/05/what-i-learned-about-agi-at-a-...

RajT88 1y ago

I am reminded of a strange issue I had with a DV Cam which I took on a "tiger cruise". The TC is where you visit your family aboard an aircraft carrier on the way back from a tour - in our case we rode the boat from Honolulu to San Diego. When on deck, the video would get scrambled every 3 seconds. It was a weird issue! I soon figured out it lined up with the sweep of the radar array - makes sense. Knowing I was dealing with radiation of some sort, I reasoned if I kept my phone angled so the battery (filled with heavy metals) between the radar array and magnetic heads, the video would no longer stutter every 3 seconds. Worked like a charm.

pclmulqdq 1y ago

Post-silicon debug of flip-chip parts is sometimes done by shining a laser on the chip at a very specific spot and detecting backscatter from the laser spot to determine if a transistor is on or not. If you turn the laser power up, you can switch specific transistors open or closed. Semiconductors in general are pretty sensitive to light, which is why they are usually packaged in a way that keeps them dark during operation.

prpl 1y ago

I used to use xenon flashes to calibrate latencies to calibrate data streams. I had a few different SDR devices hooked up to consumer hardware, and a high resolution/accuracy (50ns) time device I could control a xenon flash with. I’d trigger the xenon flash and basically just inject the flash in the data.

johnea 1y ago

This also happened to me. I guess it was the late 1980s. I was programming UV erasable microcontrollers in quartz-windowed ceramic packages. Once I had the whole multi-processor distributed system up and running, I snapped a photo with my flash (film) sports camera. Everything crashed! I also had to repeat the process reliably a couple of times before I was convinced it was the flash that caused it.