Any brown-out shut down control pin for Edison running linux?

[dchen51]

I am considering Node-Red/Linux on Intel Edison module in my design.

Linux needs to be shut down properly, so I added a supercap to keep it alive for extra period after the power is removed. The supercap controller has a output control to indicate loss of external power. If I connect it to the PWRBTN# of Edison module, would it be enough to force Edison/Linux to shutdown properly or should I connect it to a GPIO and monitor this flag and tell linux to shot down?

Thanks for your help!

[idata]

Hi Saxe,

I'm not that familiar with Node-Red, I understand that with Node-Red you can "assemble" hardware devices together. But I don't fully understand the shutdown section of the process. Could you please explain a little why is it necessary to do a clean shutdown?Personally, I've never tried to shut down the Edison module while having a battery connected to PWRBTN so I want to investigate a little bit more about this. For now, I would suggest you to go with the second option, using a GPIO for monitoring and then shutdown.I'll be waiting for your reply.Regards,-Pablo

[dchen51]

My device is not power by battery, and my supercap can only last a dozen seconds or so

Linux writes to system file frequently, if one simply remove the power, there is a chance the file system got messed up.

[idata]

Hi Saxe,

A shutdown command can be issued to Edison embedded Linux but you will need a signal from the power source that when it lose power it pull down one of the GPIO LOW and a systemd service monitor that GPIO and when it goes LOW it calls shutdown command. So I guess that that along with your supercap circuit should solve your issue. Or at least will prevent the system from abruptly shutting down.Regards,-Pablo

[idata]

Hi Saxe,

Do you have updates on this case?Regards,-Pablo

[dchen51]

Since Edison doesn't have built in support to shut down based on state of GPIO or POWERDOWN input, I will have to rely on a watch dog program to monitor a GPIO and proceed to shut down when necessary

[idata]

Hi Saxe,

Yes, for now I believe that would be a better option. We can pass your feedback to the development team. It would be a really useful implementation to have the option to shut down the Edison based on a GPIO state or powerdown input.Regards,-Pablo

[dchen51]

I would like to add another one to the wish list:

A true battery back up input for RTC on Edison.

The current VBAT_BACKUP is designed to provide charging for supercap or rechargeable lithium cell to keep the RTC during short removal period. How about a TRUE battery back up like the one on PC or many other microprocessors so that we can keep the RTC running for years

[idata]

Hi Saxe,

We want to let you know that both of your comments have been passed to the development department. Both implementations would be of great help for the users, so hopefully we would see this in the future.Regards,-Pablo

[dchen51]

Thanks!