While not familiar with the Pi2, I guess I have learned something. Never would have dreamed of a photo-sensitive chip outside of a eprom. Especially in the power supply area. They must use a on-chip led/photo transistor as a flip/flop toggle of the power. Opto-isolation. That would make sense. I have seen chips with just that but have not used them. A good lesson on new analog things to troubleshoot. All these micro-controllers are susceptible to digital rfi/rfp noise. Proper shielding your controller is still best practice regardless. Unless you like surprises that make you scratch your head. ...mike/kb8jnm

Hi Mike & Everyone,

My initial questions (and alarm) were if the RPi2 might be excessively sensitive to external EMI---something like that can be really hard to deal with around high RF environments.

But, after reading more threads, it appears this issue is truly light sensitivity in one of the switching PS chips (U16), due to how it's encapsulated (or lack thereof!) in plastic. Adding a small light shield apparently fixes this issue, based on what other testers say.

I don't yet have a RPi2, so I can't test.

73, David KB4FXC

On Sun, 8 Feb 2015 mike@midnighteng.com wrote:

...

Not having tested it specifically, I would find it plausible for a xenon flash in very close proximity to a micro-controller create a problem but only in this way...

RFI/EMP burst during flash, a pulse being picked-up on circuits. If not RFI changing something directly in ram, EMP could just put a extra binary digit in a stream of data or a extra pulse in the clock line. The later in the clock line being most probable for a lock-up. Not from the flash of light. The broad pulse comes from it's ballast. The wires attached to it and the bulb act as a antenna.

If it is a problem with a strobe light, I'll bet you could get a similar action from a close proximity GSM cell phone during certain phone actions. And I would also bet you could find that the Pi would not be the only type of micro-controller than can be affected by this type of thing.

Not to worry, Shield your Pi like you should be doing in any case and provide sinks for RFI on all lines in and out of the shielded area. This would be normal protection in a RF hostile environment. Radio 101 - It should never be a real issue in a properly constructed repeater.

...mike/kb8jnm

...

Hi Everyone,

I just saw this thread in another newsgroup. Basically, they're saying

the

...

Pi2 will hang/crash if subjected to a close xenon camera flash discharge!

Weird! Can anyone confirm if this is true? ...If they're sensitive to a flash, they might be sensitive to RF as well. Perhaps an EMP issue?

Here is a link to the thread: http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=99042

Again, I have NOT personally confirmed this report, but am sitting here looking puzzled!

73, David KB4FXC

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