Talk:Raspberry Pi/Archive 5: Difference between revisions

Revision as of 06:27, 14 March 2015

Revision as of 06:17, 18 March 2015

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::::::Changed power range, shortened CPU info, shortened Linux info, sent request for RotateBot to rotate the RPi2 photo (so it will take up less vertical space) (actually we need a better photo). It was 1 WEEK until you posted a response about the infoboxes, so I assume most people don't care or feel its ok, otherwise they would've thrown rocks at me sooner. Since this article supports both RPi1 and RPi2, and I assume there will be more RPi2 models, then its worth splitting the infobox now. All the RPi1 info is not easy to tell which is which, so throwing RPi2 into the mix makes it even harder to understand. Thanks for the response. • [[User:Sbmeirow|<span style="color:#8D38C9;">Sbmeirow</span>]] • [[User talk:Sbmeirow|<span style="color:#8D38C9;White;">Talk</span>]] • 09:11, 10 February 2015 (UTC)

:::::::Thanks, it looks a little better now with the long list of distros gone. Although I still believe a single infobox may be better. What's your opinion on how the [[iPad]] article deals with this issue? [[User:Stickee|Stickee]] <small>[[User talk:Stickee|(talk)]]</small> 09:54, 10 February 2015 (UTC)

== The photosensitivity paragraph ==

Last night, I made [https://en.wikipedia.org/w/index.php?title=Raspberry_Pi&diff=646309470&oldid=646261703 this edit] (plus two smaller clarifying edits to the same paragraph right afterward), and [[User:Sbmeirow]] [https://en.wikipedia.org/w/index.php?title=Raspberry_Pi&diff=646311204&oldid=646310823 reverted it] only six minutes later, including restoring a factually incorrect statement that I'd corrected. This is what I wrote:

: In February 2015, a [[switched-mode power supply]] chip, designated U16, of the Raspberry Pi 2 model B version 1.1 (the initially released version) was found to be vulnerable to flashes of light,<ref name="U16 forums">{{cite web | url=http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=99042 | title=Raspberry Pi Forums: Why is the PI2 camera-shy? | author=several authors | publisher=Raspberry Pi Foundation | work=Raspberry Pi Forums | date=7–9 February 2015 | accessdate=9 February 2015}}</ref> particularly the light from [[Flashtube#Xenon|xenon camera flashes]] and green<ref name="U16 Hackaday">{{cite web | url=http://hackaday.com/2015/02/08/photonic-reset-of-the-raspberry-pi-2/ | title=Photonic Reset of the Raspberry Pi 2 | publisher=Hackaday | date=8 February 2015 | accessdate=8 February 2015 | author=Benchoff, Brian}}</ref> and red [[laser pointer]]s. However, other bright lights, particularly ones that are on continuously, were found to have no effect. The symptom was the Raspberry Pi 2 spontaneously rebooting or turning off when these lights were flashed at the chip. Initially, some users and commenters suspected that the [[electromagnetic pulse]] from the xenon flash tube was causing the problem by interfering with the computer's digital circuitry, but this was ruled out by tests where the light was either blocked by a card or aimed at the other side of the Raspberry Pi 2, both of which did not cause a problem. The problem was narrowed down to the U16 chip by covering first the [[system on a chip]] (main processor) and then U16 with [[Blu-Tack|opaque poster mounting compound]]. Light being the sole culprit, instead of EMP, was further confirmed by the laser pointer tests,<ref name="U16 Hackaday"></ref> where it was also found that less opaque covering was needed to shield against the laser pointers than to shield against the xenon flashes.<ref name="U16 forums"></ref> The U16 chip seems to be bare silicon without a plastic cover (i.e. a [[chip-scale package]] or [[wafer-level package]]), which would, if present, block the light. Based on the facts that the chip, like all semiconductors, is light-sensitive ([[photovoltaic effect]]), that [[silicon]] is transparent to infrared light, and that xenon flashes emit more infrared light than laser pointers (therefore requiring more light shielding),<ref name="U16 forums"></ref> it is currently thought that this combination of factors allows the sudden bright infrared light to cause an instability in the output voltage of the power supply, triggering shutdown or restart of the Raspberry Pi 2. Unofficial workarounds include covering U16 with opaque material (such as electrical tape,<ref name="U16 forums"></ref><ref name="U16 Hackaday"></ref> lacquer, poster mounting compound, or even balled-up bread<ref name="U16 forums"></ref>), putting the Raspberry Pi 2 in a case,<ref name="U16 Hackaday"></ref> and avoiding taking photos of the top side of the board with a xenon flash. This issue was not caught before the release of the Raspberry Pi 2 because while commercial electronic devices are routinely subjected to tests of susceptibility to radio interference, it is not standard or common practice to test their susceptibility to optical interference.<ref name="U16 forums"></ref>

{{Reflist-talk}}

This is what Sbmeirow reverted it to:

: In February 2015, the U16 [[switched-mode power supply]] chip of the Raspberry 2 was found to be vulnerable to Xenon light, from for example the [[Flashtube#Xenon|flash of many camera phones]]. The U16 chip seems to be raw silicon without a plastic cover, and since covering the chip with non-conducting shielding still blocks the effect, the effect seems to be due to visible light, possibly based on the [[photoelectric effect]].<nowiki><ref>http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=99042</ref></nowiki>

My version was superior in the following ways:

* It provides more information, explaining the mechanism of the problem and how people investigated it.

* It adds a second reference.

* It wikifies the existing reference (which was just a URL before).

* It corrects "[[photoelectric effect]]" to "[[photovoltaic effect]]"; the photoelectric effect is the release of electrons from illuminated metal in a vacuum (obviously irrelevant), while the photovoltaic effect is the disturbance of electrons in a semiconductor by light (what's happening in U16).

* It clarifies that the chip is designated U16 in the context of the RPi 2, rather than being a type of chip known as U16.

It was inferior in the following ways:

* It is longer.

I knew at the time that it was long, and I expected other editors to shorten it and/or make a section for it, but I didn't expect anyone to just delete it for being too long, completely ignoring every advantage my version had, especially factual accuracy. This was also time-sensitive: I wanted to get factually correct and complete (as much as was known) info available before news sources started writing articles about the problem. Several such articles were published today. Most of the ones from technical sources didn't mistakenly mention the photoelectric effect (even though the [http://www.raspberrypi.org/xenon-death-flash-a-free-physics-lesson/ Raspberry Pi Foundation article they quoted] did), but [http://www.bbc.com/news/technology-31294745 the BBC article] and [http://www.belfasttelegraph.co.uk/life/technology-gadgets/raspberry-pi-2-is-camerashy-computer-resets-if-pictures-are-taken-of-it-30978316.html the Belfast Telegraph article] did. The BBC even explained that the photoelectric effect earned Einstein his Nobel Prize (though explained the effect incorrectly), so they probably came to Wikipedia at least for that. I haven't (can't) read every article written about the problem, but I expect the several I read are representative (first page of Google News results for 'raspberry pi'). Importantly, the two mainstream articles got it wrong, and they're the ones that people who aren't already familiar with the issue (or Raspberry Pi in general, or the two effects) are more likely to read. So, I think if the correct information had remained in the article for the rest of the day, rather than being replaced with a reiteration of the mistaken reference to the photoelectric effect, many laypeople being given incorrect info could have been avoided. (Note that I'm not saying anything about the laypeople's opinions of the Raspberry Pi 2 in light of this issue. It's not Wikipedia's job to promote products, but it is Wikipedia's job to provide correct and reasonably complete information.) I have now reverted it to my version and I expect that my version will be the basis for future edits of this paragraph for the reasons listed above. [[User:Ian01|Ian01]] ([[User talk:Ian01|talk]]) 10:16, 10 February 2015 (UTC)

:This might be a good time for you to take a look at [[WP:BALASPS]] and [[WP:RECENTISM]] (in reference to the length). The longer version gives undue weight to the the U16 issue, and as such makes it seem like a bigger issue than it is.

:There are certainly improvements, but most of them (bullet points 2-5) could be made to the shorter version without increasing it's length. [[User:Stickee|Stickee]] <small>[[User talk:Stickee|(talk)]]</small> 10:56, 10 February 2015 (UTC)

::It is excellent information, seriously I love detailed information, but...

:# I reverted it because it was TOO LONG, per [[WP:BALASPS]], not because the previous text was better.

:# If you knew it was too long, then why didn't you shorten it before posting?

:# If you knew it was too long, then why did you restore it a 2nd time without shortening it?

:# It's NOT the responsibility of other Wikipedia editors to be your personal "[[Copy Editor]]". It is your responsibility to shorten it.

:: • [[User:Sbmeirow|<span style="color:#8D38C9;">Sbmeirow</span>]] • [[User talk:Sbmeirow|<span style="color:#8D38C9;White;">Talk</span>]] • 19:24, 10 February 2015 (UTC)