That's great.

Sounds like the card was still in delivery-of-response state, so it
was ignoring the new commands.

On Fri, Mar 31, 2017 at 10:44:38AM -0300, enkitec@gmail.com wrote:
>=20
>      James, the CMD12 trick solved the problem! Thanks for your idea!
>      After some investigation I found that two dummy reads before CMD25=20
> also works.
>      The last command I issued on the card initialization phase was CMD9=
=20
> to read the card CSD.
>      It seems the CSD response has 18 bytes to read instead of the=20
> regular 16.
>      So these cards need two more reads after CMD9 to be happy!
>=20
>      Regards,
>      Mark Jordan
>=20
>=20
>=20
> On 30-Mar-17 22:34, James Cameron wrote:
> > On Thu, Mar 30, 2017 at 12:04:10AM -0300, enkitec@gmail.com wrote:
> >>       I've got some micro SD cards that work ok when connected to a PC
> >> but doesn't read/write via SPI.
> >>       My hardware works with several card brands. Never saw a problem
> >> until now. It is an ATMega8.
> >>       These cards all initialize correctly via SPI but answer CMD25 wi=
th
> >> 0xC1 and CMD18 with 0xC2. The correct answer should be 0x00.
> > Not only that, but the response token should have zero MSB to be
> > treated as legitimate.  0xC1 and 0xC2 do not have a zero MSB.
> >
> >>       Can't find any solution to this odd behavior. Spent hours on Goo=
gle
> >> but no luck.
> >>
> >>       Any suggestions?
> > Is the card offering more bytes than you read?  There's a legitimate
> > option in the specification to send more bytes; format R1b.
> >
> > I would try a CMD12 after detecting the bad reply, then try the CMD25
> > or CMD18 again once more, see if it is different second time.
> >
> > You might capture the entire conversation and attempt a materials
> > return or support request based on non-compliance.  ;-)
> >
> > Likely that SPI mode is not as well tested on new card firmware,
> > especially firmware from rushed or low-cost production.
> >
> >>       Thanks.
> >>       Mark Jordan
>=20
> --=20
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--=20
James Cameron
http://quozl.netrek.org/
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