Whether unplugging the DC power directly affects the working file system or emmc flash

Autonomous Machines Jetson & Embedded Systems Jetson Nano
#1

Hi,
Whether unplugging the DC power directly crash the working file system or damage the emmc flash.

May I ask what is the lowest operating voltage of Nano? Is there a mechanism on the software to detect too low power supply voltage and trigger the software to shut down? If there is, I want to add a large capacitor to the power supply.

#3

hello Ricardo_2007,

may I know what’s the actual use-case? it’s not safe to unplug power-supply during image flash.
please access Jetson Nano Product Design Guide, you should refer to [Chapter 5. Power] for more details.
thanks

#4

FYI, even if there is no electrical damage from cutting power (e.g., you have a surge suppressor and so there isn’t a dangerous power spike) you can expect it to corrupt the filesystem. Should the journal be enough to deal with it, then you’ll only lose the data which has not yet been committed and you won’t need any intervention. If there is too much data for the journal at the moment of cutting power, then the filesystem will need to be repaired, probably requiring user intervention.

#5

Dear Jerry and Linuxdev,

The scenario we are concerning is not during the flashing operation of the EMMC, but for the normal operation, as the rootfs is on the EMMC, and our application is running on the memory and possible read/write data from/to the EMMC during operation.
In this case, if the user shut down the power directly instead of use the shutdown option from the desktop enviroment, would it possiblely cause damge to the EMMC or the rootfs?
And as we consider to treat this as a normal operation for the customer, they may perfrom this kind of operation from time to time, would this cause the damge to the EMMC or the rootfs, and thus impact the life-time of the system?

Thanks!

#6

hello yawei.yang,

there is a shutdown latch circuit design in module for this. sudden power loss on VDD_IN will trigger force_off;

please access Jetson Nano Product Design Guide via download center and check [Chapter 5 Power].
you may also refer to [Figure 5-5. Power Down –Sudden Power Loss] for the sequence.
thanks

#7

Thanks Jerry, for the explanation,

So with the shutdown latch circuit, the force_off would be triggered when a sudden power loss happened.
For further understanding, does this force_off include the necessory protection methods, so that the EMMC, memory would not be damaged? thanks!

#8

hello yawei.yang,

in general, following the sequence. sudden power loss may not damage storage or file system.