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Is it possible to store data on a MMC card without using FAT

 
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arunb



Joined: 08 Sep 2003
Posts: 492
Location: India

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Is it possible to store data on a MMC card without using FAT
PostPosted: Fri Sep 07, 2007 4:58 am     Reply with quote
Hi,

I would like to use a MMC in a datalogger that uses a FRAM and a 16F648A. Instead of storing data using FAT or any other filesystem I would like to directly store data onto the MMC, is this possible ??

arunb
Miniman



Joined: 30 Apr 2007
Posts: 44

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PostPosted: Fri Sep 07, 2007 5:20 am     Reply with quote
Yes it is. You could use the mmc_spi.c driver from ccs
asmallri



Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia

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Re: Is it possible to store data on a MMC card without using
PostPosted: Fri Sep 07, 2007 7:05 am     Reply with quote
arunb wrote:
Hi,

I would like to use a MMC in a datalogger that uses a FRAM and a 16F648A. Instead of storing data using FAT or any other filesystem I would like to directly store data onto the MMC, is this possible ??

arunb


If you are using the FRAM and the MMC card on the same SPI bus then you have a problem. You need to write 512 byte blocks to the MMC card but you do not have 512 bytes of RAM on this PIC to act as a buffer. Once you start writing to the SD card, you cannot desert the CS until you have written the block - the challenge is how do you read from the FRAM while keeping the MMC card selected.
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arunb



Joined: 08 Sep 2003
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RE:
PostPosted: Fri Sep 07, 2007 7:21 am     Reply with quote
Hello,

Thanks for the reply,

The MMC and the FRAM are on different buses.

Data read from the FRAM is transferred to the MMC by the PIC, the same way data read from the MMC is transferred to the FRAM by the PIC.

arunb
renato



Joined: 02 Sep 2005
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PostPosted: Fri Sep 07, 2007 9:15 pm     Reply with quote
hi, im go work to this mmc_spi.c


im need one exemple the application the include in code.

Plz send me one exemple of code.

10x
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