XO-1 SD card access during boot-up

[John Watlington]

On May 30, 2012, at 3:42 AM, James Cameron wrote:

> Agreed.  I meant a proper power cycle, not the type provided by XO-1
> without supply discharge.  My point is that it is hard to know if
> leaving the power on and using CMD0 is any better than turning the
> power off.  We already have a delay in the firmware to provide 250ms
> fall time for XO-1 and XO-1.5.  We could increase that, but it will
> slow booting still further.


I misunderstood the question, and can answer that one.
CMD0 only works if the card is already in a working state.
Power cycling will always reset the card to a working state.

A while back, Microsoft finally got tired of the number of computers
that could get themselves wedged into a state which required a hard
power cycle, and starting insisting that the ability to power cycle the
SD/MMC card was required for Windows certification.

Cheers,
wad