Re: Nor flash menroy

Hi chang

the erase block is the sector in your flash. The chip uses the bank for
simultanious read/erase or read/write. You can erase a complete sector only.

I've looked in the spec and hope i've understood the following correctly:

The chip is devided in 16 Banks, Bank 15 has a diffrent layout than the
other ones. This must be considered, when writing a driver for that flash.
Other flash types like intel p30 have such blocks, with a different layout
than the other ones too.

Eyery Bank of the 128MB chip is organized in 8,388,608 bytes(8MB- see
General description in spec) , and sector 0-14 consits of 120 Sector which
results to 120 MB Flash memory. So every sector in bank 0 - 14 must have a
size of 1MB.
The sector itself is addressable via 64Kwords Addresses, so the least unit
you can address is 16 Byte.
The filesystem operates on sectors. You can split you sectors (erase blocks)
into smaller untis (512 bytes units + sector info) for file system access.

best regards

Hi ,
Enough thanks to all of you
Hi saga/ALL,
As per you the bank and block are same? and i am using a old nor which
is alredy in market "S29NS128N" and it is showing the layout like this
way :
S29NS128N:

->Bank 0-14 Sectors
120 Mb total:
.Quantity =120 Size =64 Kwords

->Bank 15 Sectors
8 Mb total:
A)Quantity=4 Size =16 Kwords
B)Quantity=7 Size =64 Kwords

I am using it for flash media but i am just confused that if this is
layout then what will be the block size and are there different
types(density) of blocks are present ?

Please help me to show the right way to read this nor .


On Jul 15, 4:23 pm, "JamesCool via PocketPCJunkies.com" <u42351@uwe>
wrote:
Hi Chinmoy,

As you mentioned, the FAL will write the metadata into sector infor area, if
this location is not being erased first, it still can write somethings on it?

Best regards,
James





Saga wrote:
Hi chang

i hope this very short description will help you:
A nor flash memory consists of multiple erase blocks (your bank) and one
block is divided into multiple sectors plus block metadata. Every Sector is
divided in sector data to save the data and sector metadata to save the state
of a sector.
You can read or write from/ to any memory position inside the block, but to
erase something, you must erase the complete block. This is NOR design.
Filesystems operate always on sectors, which is the single unit of a block.
But the filesystem does not operate on the NOR directly, it uses a CE
component called FAL, which is the interface to the flash. and manages all
flash sectors. If the filesystem erase something, the appropriate sector
will be marked (in the metadata area). There is a FAL machanism called
background reclaiming, which checks all the sectors on flash and, if it is
neccesary move sectors of one block to another one to erase the old block and
free ressources. The Filesystem does not notice the changes, because it uses
the FAL to acces to the flash. The FAL translate the Filesystem flash sector
address to the real sector address.

So, on NOR you can only erase blocks, the Filesystems access Sectors, which
is a unit of a block. The OS manages the sectors and delete blocks if
necessary.

regards

Hi ,
I am a very new in nor desigining . While reading the spec/dat*** i
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Thanks
Chinmoy

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