Lpc2000

--- In lpc2000@yahoogroups.com, "lpc2100_fan" <lpc2100_fan@y...> wrote:

> have a look at the application note about using Flash as
> EEPROM in the files section of this forum.
> Name: EE_Demo.zip

Thanks to this post by lpc2100_fan, I had a closer look at ECC in the
user manual for 214x.

I took the statement on page 297 "The operation of ECC is transparent
to the running application." on face value, and was not interested in
the implementation details.

Is the case in every flash, disk or other system I know, ECC has
always been transparent to the extent most manufacturers do not make
any mention of this in their programming or user manuals for flash
memory, disks, etc.

Many times they prefer not to highlight ECC as the strength of their
ECC regime usually exposes fabrication process control limitations.

However, when I read further down, I found out that, ECC is not after
all transparent as claimed.

1/  You *cannot* make use of the NAND/NOR flash characteristics for
implementing a flash file system.

2/  When you write incrementally to an erased block, you *must* ensure
each 4-byte block does screw up the ECC algorithm used.  [You do not
know what the algorithm is because it is supposed to be transparent.]

3/  The boot loader and IAP calls being advertised as to to hide flash
implementation details apparently does not hide this "property" of the
flash.

I now have to put exclusions in my flash file system package -- that
it will not work on LPC for the above reasons.