Dan Miner wrote:
From: Chris Liechti
Sent: Friday, January 23, 2004 5:16 PM
i think its actualy not that worse. if you log to a large
file, you can write block after block, each datablock is
only written once. of course the fat table and the
directory entry has to be written more often. but you can
keep the write rate there down too, by caching the FAT table
or at least one block.
I've never actually done this yet, but for a future data logging
project, I was planning to create a single large file that fills
the size of the card (minus FAT and other overhead). Then, the
MSP430 will only write into the file area. That way, the MSP
doesn't need to know FAT system but only where the first sector
of the big file is and the MMC is still readable on a PC host.
if you write a big file, it does not need to be continuos on the disk.
the clusters may be used in any order. and that will happen if you dont
start with a fresh formated card. thus, you have to read the FAT table
and find out which cluster is the next, you also need to parse the
directory entries to find out which is the first cluster of the file.
see my notes in the other mails. i had a similar idea as you :-)
chris
