[En-Nut-Discussion] FAT filesystem and SD/MMC cards

[Brett Abbott]

Hi

Im just porting a mixture of Dusan's and xfash to ICCAVR.  Quite a bit 
to change it to work on Ethernut 2 but getting close.  Will let you know 
more in a week or so.

Cheers
Brett

Harald Kipp wrote:

> Hello Arnfinn,
>
> Bad news. There is a simple FS for serial dataflash chips
> http://www.ethernut.de/en/projects.html
> contributed by Dusan Ferbas. It doesn't take care of wear out and
> the code is a bit old. No idea if it will still work with the
> latest Nut/OS.
>
> PNUT is optimized (better say simplified) for RAM. It may be
> too difficult to make it work on Flash Cards.
>
> As far as I understood, MMC/SD Cards contain a patented algorithm
> to avoid flash wear out, even if the FAT is written to the same
> block over and over again. Anyone with more insight?
>
> In general I'd prefer a journaling FS, because it would be useful
> for all kind of flash memory, not just patented FAT. My interest
> in the area is enormous, but the required effort...well.
>
> The ecos JFFS2 doesn't look bad. Unfortunately it's GPL'ed and
> won't fit to Ethernut's BSD licence.
>
> Harald
>
> At 16:40 23.06.2005 +0200, you wrote:
>
>> Hello!
>>
>> I'm trying to find out how I can read and write files to a SD/MMC 
>> card using a newly acquired Ethernut 2.1b.
>>
>> I have made a mount for a SD/MMC card reader, a voltage divider for 
>> the output from the microcontroller, and connected it to the SPI bus. 
>> I have downloaded the "nutmmc" example from 
>> http://usbdip.de/en/nutmmc/ and it seems to run without problems on 
>> the hardware.
>>
>> Now, I noticed that it is not possible to write files with the FAT 
>> code that I have found, and I wonder if there has been some 
>> development here lately. Is there somebody I can ask for some help if 
>> I have to write the functions myself? You can have whatever code I 
>> manage to come up with, if it would be of any interest. :)
>>
>> Is there perhaps an alternative to the FAT file system when it comes 
>> to reading and writing the memory card? I noticed something called 
>> PNUT; is it usable for this kind of application? I don't need to read 
>> or write to the card from any other device than the Ethernut card, so 
>> I just need (wish for) an easy and simple way to handle files really...
>>
>> Any help is appreciated!
>>
>> Cheers,
>> Arnfinn Aas Eielsen
>
>
>
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>
>

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Brett Abbott, Managing Director, Digital Telemetry Limited
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