Getting started with FAT Filesystem on SD/MMC cards over SPI

Gene Smith gds at
Thu Sep 11 20:32:13 UTC 2008

What you are talking about here my h/w does and it is something I need 
to do too. However, at this point I don't have a clue how. So a "HowTo" 
would be most appreciated and I could contribute what I learn.

All I have worked with is the IMFS in a simple way.


Robert S. Grimes wrote:
> Hello,
> My hardware provides support for SD/MMC flash cards over SPI, so now I 
> need to implement suitable drivers for this.  Because it would need to 
> be read by Windows machines, and because it is sufficient for my 
> application, it seems the dosfs is the way to go.
> I've got a low level SPI driver for my BSP (powerpc/virtex under RTEMS 
> 4.8), and I've written some chip drivers on top of that, so I'm 
> comfortable with the SPI level.
> But where do I go from here?
>    1. How do I "include" the dosfs in my application?  Is it a matter of
>       #define CONFIGURE_ macros, and if so, which?  (As an aside, is
>       there one central place where all these macros are defined?  If
>       so, I haven't found it...)
>    2. How do I get dosfs to work via the SPI bus?  What must my driver
>       look like?
> Any pointers or roadmap well appreciated - TIA
> -Bob
> P.S. Sounds like a request for a "HowTo" on my part - I'd be happy to 
> write one for the Wiki...

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