Re: Handling power failure - MPC5200

["Mark Chambers" <markc@mail.com>]

> > > Capacitors on the supply provide me with some
> milliseconds to repond
> to
> > > power failure, which I would
> > > like to use to do as much cleanup as possible before power is
> > > totally gone.  In particular, I am concerned
> >

>What I've seen is marketing bullet points saying the cards can survive a
power loss event with no loss of data, but when I read the >detailed CF
specification, the disclaimer was that power had to be held up for X mSec (I
forgot what X was, 2mSec or 10mSec most >likely) after the last write
operation.  The marketing bullet point was exactly that: marketing.  The
real requirement levied on the user
>(you) was that you had to have X mSec power hold up after the last write
operation (i.e. a X mSec power fail warning with no write >operations after
the PF warning).  The hold-up requirement gave the CF internals enough time
to complete a flash write cycle.

One simple use for the power fail interrupt would be to just turn off
interrupts and loop until power fail.
This would insure that a write or erase operation completed fully.
P.S. Don't forget to cover the situation where power comes back rather than
going all the way down!

Mark Chambers
wvcomputronics.com