The new, more powerful Raspberry Pi 2 credit card-sized computer has a small and rather surprising flaw: flashes of light will cause it to spontaneously crash and power off.



The curious issue was first spotted by the self-proclaimed “discoverer of the Pi2 xenon death flash” and Raspberry Pi 2 user PeterO, who posted his discovery on the Raspberry Pi Foundation’s message boards.

“My PI2 is camera-shy! Taking its picture with a flash causes an instant power-off! I’ve done it three times now and same thing happens each time,” said PeterO.

It wasn’t long before the flaw was verified by Raspberry Pi engineer and moderator known only as jdb, replicating the crash.

A small gaggle of Pi 2 users started taking pictures of their unprotected boards with a variety of cameras and cameraphones, quickly narrowing the problem down to the brighter Xenon flashes – LED flashes common on smartphones didn’t cause the bug.

“With a Canon Ixus 60 (handheld compact camera), its flash reliably locks up the Pi. You need to be closer than about 50cm to make it happen, though,” said jdb.

Photoflash glitch

Another user mikerr confirmed that the previous generations of the Pi board were all immune to the “xenon death flash”.

The components, chips and resistors of the Raspberry Pi are exposed, part of its DIY aesthetic. It seems that the chip with a weakness for flashing is the tiny U16 chip, part of the power supply circuit.

Flashes of light at the right frequency seem to interrupt the supply of power to the rest of the board, according to another Pi user, tdicola. Attaching an oscilloscope to the board showed that not only does it cause a power interruption when exposed to the light, but also a power spike when exposed to the flash without being plugged into a power supply.

“It’s a feature not a bug, it teaches you about the photoelectric effect,” said tdicola.

In true Heath Robinson fashion, a bit of Blu-Tack or similar to cover the chip solves the issue, while sugru offers a more permanent solution. Equally, placing the Pi 2 in an opaque case should do the trick.