On Tue, Mar 31, 2015 at 04:24:26PM +1300, IVP wrote:
> > Okay, so code for missing DO low at the expected time.
>=20
> Frustratingly, DO going low isn't as predictable as expected. Often/
> usually it will go low after the 11th SPI write (ie the 0xFF with CS
> low after the 10x8 clocks with CS high), but now I'm seeing it stay
> high during that time and go low in the middle of the CMD0 bytes
> following, and the file will play successfully. A file fail always happen=
s
> before this point so it's not looking possible to use DO as a reliable
> indicator. If DO was reliable, then I could get the s/w to go back and
> keep doing the 74 clocks again
>=20
> Only a time-out trigger reliably detects inactivity
>=20
> >> I'm hoping the mysterious occassional click will get fixed too
> >=20
> > I hope not.  Can't stand not knowing the cause of problems.  ;-)
>=20
> The click is getting worse, noticeably louder and noisier and more
> frequent. 3 out of 4 plays are now bad. And it plays badly in 3
> distinct ways too. There's a pop, a crunch and a knock. Not in a
> regular order and mixed up with good plays
> =20
> I'm thinking of capturing what's coming into the SPI from the card
> and comparing it with the original file. I'll have to get that 512kB
> SRAM board running first though
>=20
> Since the first fail after 54 hours, the card is definitely getting
> worse. After just a few minutes of running time since then, which
> includes a lot of fails a few seconds apart that needed power
> cycling, the fails are getting closer together. Several times on the
> first access to the file.

An increasing failure rate is a symptom of electrostatic discharge
damage.  If I recall correctly, the original ESD event can make a hole
in a gate that later changes behaviour as a result of thermal cycling.

> The card always does the power-up initialisation though, and eg
> file names are bit-bang transferred from its FAT to the 18F for
> display
>=20
> What I will try next is a block write after reading the FAT and
> before accessing any files. Also read the card's registers so I've
> something to compare with after the next format
>=20
> Joe
>=20
>=20
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>=20
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--=20
James Cameron
http://quozl.linux.org.au/
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