Recently [Jeff Geerling] has been tinkering with FireWire in order to use some older gear, which includes the use of a Raspberry Pi HAT called the Firehat. This provides a 6-pin FireWire port courtesy of the VIA VT6315N PCIe-to-FireWire chipset. As is typical with USB gear today as well, some FireWire gear requires more power than a port can provide, requiring the use of a powered hub. Unfortunately the use of a powered FireWire hub caused a bit of a conflagration event on [Jeff]’s desk.

Part of the issue appears to be that this Firehat board was designed as a companion to the Equip-1 DV capture device, with no attention paid to the idea that someone might be backfeeding power from an attached hub. As a result the VIA chip cried uncle and let out the magic smoke.

With this Firehat board taking its name clearly a bit too literal, [Jeff] will be reporting his findings to the developers, in the hope that perhaps some diodes or another solution against backfeeding can be added to the final design. Fortunately he was sent this board for testing prior to public release, so this definitely shows a clear flaw that can now be corrected.

We hope that [Jeff] has a good HEPA air filtration setup in his office to get rid of the acrid magic smoke, as it’s not meant to be enjoyed for long periods.

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