Empty battery shutdown resets to pre-initialization state

[craigraw]

After doing a lot of QR scanning testing recently, my batteries ran empty causing the Passport to shut down. It tried to reboot, but ended up in a cycle of red light/blue light at the top as the boot sequence was drawing too much power from the exhausted batteries. Upon replacing the batteries, the device booted fine but reverted to the pre-initialization state, asking to scan the initialization QR etc.

It turns out I just needed to skip those parts to get back to normal operation, but this was somewhat disconcerting - I thought the seed had been lost.

Firmware v1.0.7

[FoundationKen]

Hi Craig.

Sometimes when Passport's battery is low, it can result in corruption of the user settings flash, which is where we remember if you have gone through accepting terms and other initialization among other things.

When the MCU detects such corruption (a bad read from the user settings flash memory region), it throws a hard fault. If we did nothing about this, then the Passport would not be able to continue operating and would basically be a brick.

So instead, we added a handler for this hard fault and we erase and reinitialize the user settings flash and allow boot to continue. The secure element is completely separate from this, and the seed is not affected.

If you have other settings that were lost like multisig configs, you would need to re-import them or restore from a microSD backup.

[craigraw]

Makes sense - I suspected this might be the case.

I'm not sure if it's possible to prevent the corruption by shutting down immediately if the battery becomes too low, and preventing booting in this state as well.

[FoundationKen]

The AAA batteries make this hard. In batch 2, we have a fuel gauge component that will make it possible to shutdown automatically before running out of juice.

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--- original message --- On November 11, 2021, 11:59 PM PST ***@***.*** wrote: Makes sense - I suspected this might be the case. I'm not sure if it's possible to prevent the corruption by shutting down immediately if the battery becomes too low, and preventing booting in this state as well. — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. --- end of original message ---