Hardware Watchdog Bricked Modem


I was reading up on hardware watchdogs and noticed this warning on the page

This has me concerned it not impacts our project if we want to use the hardware watchdog, but also in general since we are subject to power loss at any time.

Is this still a vulnerability on 402 bsoms?
What are the specifics of this vulnerability, in what cases could it happen?
Does random power loss to the bsom, say by unplugging usb power, have the same vulnerability?


This is covered in TAN004 and affects all devices with u-blox SARA-R410M cellular modems, which includes the B402 and B404 but does not include the B404X. Also Boron LTE, E Series LTE, and Electron LTE 402 and 404 models.

The problems is that there are certain housekeeping functions implemented on this cellular modem that, if interrupted by turning off the power, can corrupt the flash file system on the modem itself causing it to no longer be able to boot.

In the majority of cases removing the power will have no bad effects, but you should try to minimize the frequency of doing this, because we can’t guarantee that a problem won’t occur if you remove power to the modem suddenly.

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