Why are you suing a 2MB FLASH to do the log.  Why don't you just use a 2MB
FLASH to do it.
Only joking, but I couldn't resist.

Regards,

Jim

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
Harold Hallikainen
Sent: Wednesday, March 30, 2011 10:18 PM
To: Microcontroller discussion list - Public.
Subject: Re: [PIC]: what's the best way to save large data in flash memory

I'm doing something like what you described. I'm suing a 2MB SPI flash to
do logging in a system. I save 64 byte records sequentially. I keep track
of the address I'm going to write the next record to. I have a function
called FlashStreamProgram. I pass in the starting address, a pointer to
the data I want to write, and the number of bytes to write. Every time the
FlashStreamProgram detects we have gone over a sector boundary and need to
erase, it does so before moving on. I pull the data back by reading an
array similarly. When reading the log, I specify a log record number,
which converts to an address, then gets the log record. On power up, when
the system does not know where the next log record would go, it scans
through memory starting from  the bottom looking for the first erased
record (0xff in all bytes). It then uses this as its next llog address.

Harold





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