On Thu, Feb 12, 2015 at 02:46:32PM +1300, IVP wrote:
> > The compliance against standards varies considerably across
> > the market.  My guess is you've found a bug in the firmware, a
> > corner case that is exercised by your pattern of access, but is
> > not tested by the device manufacturer or firmware vendor.
>=20
> I probably shouldn't expect them to, as SPI seems more of a
> courtesy vs the licensed 4-bit i/f encountered commercially
>=20
> > - switch to a pattern of access that is known to work
>=20
> That's partly the problem. As mentioned, I have a scheme that's
> very reliable with one type of card which doesn't work with others.

Not unusual.  Many different implementations of firmware in those
cards.  Can't even rely on them staying the same over a vendor's
product lifetime.

> > Perhaps the card wants a supply voltage change; some SDHC
> > or SDXC cards require 1.8 V at higher transfer speeds.
>=20
> I have tinkered with the s/w flow quite a bit, but not tried changing
> to 1.8V. In the PC card reader which I use to transfer files to the
> cards Vdd is 3.4V

Does that reader use the higher transfer rate?  Might be time to look
at the conversation between the reader and the card.

--=20
James Cameron
http://quozl.linux.org.au/
--=20
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