SD card's and Micro SD card connections

[James Long]

Just because I botched the first try, I figured I would get some guru's to converse the issue of connecting a Micro SD card to the propeller.

I tried with a PCB and the result was less than optimum.

Anyone want to discuss the correct connection of a Micro SD card?

Thanks,

James L

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James L
Partner/Designer

Lil Brother SMT Assembly Services

[Mike Green]

I used the SparkFun breakout board for the micro-SD card socket. The connections are the same as that for the standard SD card except that there's only DO, Gnd, Clk, Vcc, DI, and CS. There's also a CD (card detect), but I don't use it.

[James Long]

Mike,

The pin out for a micro SD card is somewhat different than with a regular size SD card. The Micro card only has 8 pins, where a standard one has 9. The locations for the different items (vdd, vss, etc) are a little different.

That is the root of the confusion.

James L

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James L
Partner/Designer

Lil Brother SMT Assembly Services

[James Long]

Mike,

But the schematic at Spark Fun does solve the problem.

Thanks for the reference.

James L

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James L
Partner/Designer

Lil Brother SMT Assembly Services

[QuattroRS4]

not all microSD cards support SPI mode ..This caught me out for a bit ..

see here
en.wikipedia.org/wiki/Secure_Digital_card

Regards,
John Twomey

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'Necessity is the mother of invention'

Those who can, do.Those who can’t, teach.

[Cluso99]

QuattroRS4: I have noticed this too, but from what I have been able to determine, the manufacturers seem to always support this anyway. So which ones didn't work please?

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[QuattroRS4]

Cluso99,
Unfortunately it was an unbranded 4GB cheapie - FAT16 formatted - worked fine on PC .. but not using SPI. I'll see if I can find it and take a photo and check if it has any defining markings at all. I then bought a 4GB sandisk and it worked flawlessly .. It was only after the 'cheapie' that I researched reasons as to why it didn't work and found that many others had similar issues - and usually with unbranded cheapies!. I believe that most manufactures still support it (in the smaller memory units anyway).

Regards,
John

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'Necessity is the mother of invention'

Those who can, do.Those who can’t, teach.

[Mike Green]

FAT16 doesn't reliably support storage media larger than 2GB.· I would stay away from 4GB cards.· I don't remember whether Rokicki's routines work with 4GB media.· Some older Windows, Linux,·and MacOS versions don't support it.

[QuattroRS4]

Mike,
That is true but they can be partitioned .. As Tomas Rokiki's Routines work up to 2GB

Regards,
John

Tomas Rokiki's - 'Readme' File said...
The following table shows the range of cluster sizes you can select in
XP when formatting in order to guarantee a FAT16 volume. The number
of clusters will be the size of the card divided by the cluster size
(approximately).

min max
4M 512 512
8M 512 1K
16M 512 2K
32M 512 4K
64M 1K 8K
128M 2K 16K
256M 4K 32K
512M 8K 32K
1G 16K 32K
2G 32K 32K

If you do not select the right cluster size, your volume may be formatted
in FAT12 or FAT32, neither of which is supported by this code.

FAT16 does not support volumes greater than 4G. If you must use a 4G
card, you will have to ensure the first volume is 2G or less, and this
code will only mount that first volume. In reality this is not much of
an issue, because this code only supports the SD protocol, and cards
of 4G or larger require the new SDHC protocol. (I have no way at this
time to know if an SDHC card will default to the SD protocol for the
first portion of the card.)

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'Necessity is the mother of invention'

Those who can, do.Those who can’t, teach.

Post Edited (QuattroRS4) : 3/4/2009 9:29:06 PM GMT

[Javalin]

above 2GB you get the SHDC cards which don't work with SPI / SD card protocol's so I am told.