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Topic: Micro SD hooked up Right? (Read 3237 times) previous topic - next topic

MetroExpress

I was wondering If anyone could confirm this is hooked up right, I can't seem to find any documents that pertain to this microSD connector.

The microSD datasheet is here:
http://media.digikey.com/pdf/Data%20Sheets/Amphenol%20PDFs/101-00660.pdf

Max3002 Datasheet is here:
http://datasheets.maxim-ic.com/en/ds/MAX3000E-MAX3012.pdf

My Schematic:


Thanks a bunch.

MetroExpress

I've doubled check the connections, and the only thing I can see that might be the problem is the SD connector may be wired incorrectly. On the datasheet everything is labeled with the full names of the connections eg. Data Line(bit 2), and Card Detect

Everything worked fine on my breadboard using the SD.h library, but now that its standalone I cannot detect the SD card. :-/

If anyone has any input let me know.

Cheers
Geoff

orbitalair

You have the DI (DataIn)  grounded...should be MOSI.
It'll never work like that.

davekw7x

#3
Feb 24, 2011, 03:34 pm Last Edit: Feb 24, 2011, 04:10 pm by davekw7x Reason: 1

I've doubled check the connections...

You have drawn the symbol in a way that does not correspond to the physical layout of the package pins.  That's OK, in general, but if you look at the symbols on Page 21 of the data sheet that you referenced, and if you read (really read) the explanations there, the functionality is easier to understand.  (It's also easier to keep track of the connections if you are wiring by hand.)

Pin numbers go down from 1 through 10 on one side of the package and from 11 through 20 up the other side of the package, and the pins on the package are conveniently arranged for "flow-through" PC layout.

Anyhow,  no matter how you draw the symbol...

Pin 1 on the low-voltage side corresponds to pin 20 on the high-voltage side
Other signal pins correspond as follows:
3 <--> 18
4 <--> 17
.
.
.
etc.

Bottom line:
If Pin 20 is the "SS" signal from the CPU, then Pin 1 should be connected to "CS" on the SD
If Pin 18 is " MOSI" from, the CPU, then Pin 3 should be connected to "DI" on the SD.
.
.
.
etc.


Regards,

Dave
Footnote:

The 3.3V DO from the SD can be connected directly to the MISO pin on the Arduino as you show, but, since you have a level shifter, why not send that signal through it as well?  With a direct connection, if you accidentally enable a pull-up on the Arduino MISO, or if the pin, somehow gets configured as an output for some sketch that is not using the SD, it could apply 5 Volts to the SD pin (possibly damaging the  SD).  The level shifter can make sure that no more than 3.3 Volts is ever applied to the SD.  Just a thought.

MetroExpress

Hey thanks for the reply.

Yeah so I had the SD wired up like a standard SD card, I did find the microSD pinout which explained the CS/NC/DI lol silly me.

http://www.interfacebus.com/MicroSD_Card_Pinout.html

I also ran the MISO through the level shifter. Thanks for the tip.

Geoff

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