[ECOS] Size of eCos

[ECOS] Size of eCos

[Himanshu Patel]

Hi,

What is the minimum memory requirement (code and data) for eCos kernel?

Regards,

Himanshu Patel

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[ECOS] FAT32 over NAND

[Himanshu Patel]

Hi,

We want to have FAT32 file system over NAND flash. Is it possible? What
approach should we take for developing the same?

Regards,

Himanshu Patel



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Re: [ECOS] FAT32 over NAND

[Andrew Lunn]

On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
> Hi,
> 
> We want to have FAT32 file system over NAND flash. Is it possible? What
> approach should we take for developing the same?

If you look back in the archive, last year there was some work to get
YAFFS on NAND working. I would suggest trying to build on the NAND
infrastructure that provided.

               Andrew

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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Okay...Will look into the same...

Another question...We will need to provide Flash Translation Layer. Do we
need to port the same from Linux or use them from JFFS2 or YAFFS?

Regards,

Himanshu Patel

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch] 
Sent: Tuesday, January 20, 2009 8:01 PM
To: Himanshu Patel
Cc: 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
> Hi,
> 
> We want to have FAT32 file system over NAND flash. Is it possible? What
> approach should we take for developing the same?

If you look back in the archive, last year there was some work to get
YAFFS on NAND working. I would suggest trying to build on the NAND
infrastructure that provided.

               Andrew




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Re: [ECOS] FAT32 over NAND

[Rutger Hofman]

Andrew Lunn wrote:
> On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
>> Hi,
>>
>> We want to have FAT32 file system over NAND flash. Is it possible? What
>> approach should we take for developing the same?
> 
> If you look back in the archive, last year there was some work to get
> YAFFS on NAND working. I would suggest trying to build on the NAND
> infrastructure that provided.

I implemented basic NAND flash functionality and a wrapper layer for 
YAFFS2, a file system designed specifically for NAND flash. For an alpha 
release (and maybe later on, beta release) of my code, see: 
http://www.cs.vu.nl/~rutger/software/ecos/nand-flash/

If you want FAT32, you will have to create (port from elsewhere?) a FTL 
(Flash Translation Layer) that implements lots of stuff to make FAT32 
behave in a NAND-compatible way. For a discussion of this in the context 
of UBIFS (the latest-greatest Linux NAND flash file system), see:

http://www.linux-mtd.infradead.org/doc/ubifs.html#L_raw_vs_ftl

An FTL should minimally provide:
- wear levelling
- garbage collection for released blocks
- bad block management
- write caching because programming has to be consecutive and in at most 
a few operations.

YAFFS2 implements all this already. Is using YAFFS2 an option, maybe?

Rutger Hofman
VU Amsterdam

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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Okay...Thanks...

YAFFS2 is not a possible option...As device should be able to access from PC
running Windows also through mass storage interface...

Can we make use of NFTL (NAND flash translation layer) which Linux is
providing? 

Regards,

Himanshu Patel

-----Original Message-----
From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
Sent: Tuesday, January 20, 2009 8:15 PM
To: Himanshu Patel; 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

Andrew Lunn wrote:
> On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
>> Hi,
>>
>> We want to have FAT32 file system over NAND flash. Is it possible? What
>> approach should we take for developing the same?
> 
> If you look back in the archive, last year there was some work to get
> YAFFS on NAND working. I would suggest trying to build on the NAND
> infrastructure that provided.

I implemented basic NAND flash functionality and a wrapper layer for 
YAFFS2, a file system designed specifically for NAND flash. For an alpha 
release (and maybe later on, beta release) of my code, see: 
http://www.cs.vu.nl/~rutger/software/ecos/nand-flash/

If you want FAT32, you will have to create (port from elsewhere?) a FTL 
(Flash Translation Layer) that implements lots of stuff to make FAT32 
behave in a NAND-compatible way. For a discussion of this in the context 
of UBIFS (the latest-greatest Linux NAND flash file system), see:

http://www.linux-mtd.infradead.org/doc/ubifs.html#L_raw_vs_ftl

An FTL should minimally provide:
- wear levelling
- garbage collection for released blocks
- bad block management
- write caching because programming has to be consecutive and in at most 
a few operations.

YAFFS2 implements all this already. Is using YAFFS2 an option, maybe?

Rutger Hofman
VU Amsterdam




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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Okay...Thanks...

YAFFS2 is not a possible option...As device should also be able to access on
Windows PC using mass storage interface...

Can we use NFTL (NAND flash translation layer) support provided by Linux?

Regards,

Himanshu Patel

-----Original Message-----
From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
Sent: Tuesday, January 20, 2009 8:15 PM
To: Himanshu Patel; 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

Andrew Lunn wrote:
> On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
>> Hi,
>>
>> We want to have FAT32 file system over NAND flash. Is it possible? What
>> approach should we take for developing the same?
> 
> If you look back in the archive, last year there was some work to get
> YAFFS on NAND working. I would suggest trying to build on the NAND
> infrastructure that provided.

I implemented basic NAND flash functionality and a wrapper layer for 
YAFFS2, a file system designed specifically for NAND flash. For an alpha 
release (and maybe later on, beta release) of my code, see: 
http://www.cs.vu.nl/~rutger/software/ecos/nand-flash/

If you want FAT32, you will have to create (port from elsewhere?) a FTL 
(Flash Translation Layer) that implements lots of stuff to make FAT32 
behave in a NAND-compatible way. For a discussion of this in the context 
of UBIFS (the latest-greatest Linux NAND flash file system), see:

http://www.linux-mtd.infradead.org/doc/ubifs.html#L_raw_vs_ftl

An FTL should minimally provide:
- wear levelling
- garbage collection for released blocks
- bad block management
- write caching because programming has to be consecutive and in at most 
a few operations.

YAFFS2 implements all this already. Is using YAFFS2 an option, maybe?

Rutger Hofman
VU Amsterdam




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Re: [ECOS] FAT32 over NAND

[Andrew Lunn]

On Tue, Jan 20, 2009 at 08:41:35PM +0530, Himanshu Patel wrote:
> Okay...Thanks...
> 
> YAFFS2 is not a possible option...As device should be able to access from PC
> running Windows also through mass storage interface...
> 
> Can we make use of NFTL (NAND flash translation layer) which Linux is
> providing? 

Depends on what license you want to use. If you are happy that your
entire system, is GPL, yes. However most people want to keep there
application closed, in which case you cannot use Linux kernel code.

            Andrew

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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Okay...However can you please confirm that it provides all functionality
like wear leveling, garbage collection etc...?

-----Original Message-----
From: Andrew Lunn [mailto:andrew@lunn.ch] 
Sent: Tuesday, January 20, 2009 8:45 PM
To: Himanshu Patel
Cc: 'Rutger Hofman'; 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

On Tue, Jan 20, 2009 at 08:41:35PM +0530, Himanshu Patel wrote:
> Okay...Thanks...
> 
> YAFFS2 is not a possible option...As device should be able to access from
PC
> running Windows also through mass storage interface...
> 
> Can we make use of NFTL (NAND flash translation layer) which Linux is
> providing? 

Depends on what license you want to use. If you are happy that your
entire system, is GPL, yes. However most people want to keep there
application closed, in which case you cannot use Linux kernel code.

            Andrew




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Re: [ECOS] FAT32 over NAND

[Rutger Hofman]

Himanshu Patel wrote:
> Okay...Thanks...
> 
> YAFFS2 is not a possible option...As device should also be able to access on
> Windows PC using mass storage interface...

Is this a NAND memory smart-card (MMC, SD, USB flash drive or whatever)? 
These usually come with an FTL on-board, which offers a file system like 
FAT32. You need no Flash code for that.

Is this a raw flash? So, how is it going to be accessed from Windows if 
the file system is completely in software?

> Can we use NFTL (NAND flash translation layer) support provided by Linux?

I am no Linux expert, but my feeling is that NFTL is very old, and that 
flash handling is done through UBI/UBIFS. The UBIFS link in my message 
below seems rather informative.

Rutger

> Regards,
> 
> Himanshu Patel
> 
> -----Original Message-----
> From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
> Sent: Tuesday, January 20, 2009 8:15 PM
> To: Himanshu Patel; 'eCos Discuss'
> Subject: Re: [ECOS] FAT32 over NAND
> 
> Andrew Lunn wrote:
>> On Tue, Jan 20, 2009 at 07:38:02PM +0530, Himanshu Patel wrote:
>>> Hi,
>>>
>>> We want to have FAT32 file system over NAND flash. Is it possible? What
>>> approach should we take for developing the same?
>> If you look back in the archive, last year there was some work to get
>> YAFFS on NAND working. I would suggest trying to build on the NAND
>> infrastructure that provided.
> 
> I implemented basic NAND flash functionality and a wrapper layer for 
> YAFFS2, a file system designed specifically for NAND flash. For an alpha 
> release (and maybe later on, beta release) of my code, see: 
> http://www.cs.vu.nl/~rutger/software/ecos/nand-flash/
> 
> If you want FAT32, you will have to create (port from elsewhere?) a FTL 
> (Flash Translation Layer) that implements lots of stuff to make FAT32 
> behave in a NAND-compatible way. For a discussion of this in the context 
> of UBIFS (the latest-greatest Linux NAND flash file system), see:
> 
> http://www.linux-mtd.infradead.org/doc/ubifs.html#L_raw_vs_ftl
> 
> An FTL should minimally provide:
> - wear levelling
> - garbage collection for released blocks
> - bad block management
> - write caching because programming has to be consecutive and in at most 
> a few operations.
> 
> YAFFS2 implements all this already. Is using YAFFS2 an option, maybe?
> 
> Rutger Hofman
> VU Amsterdam
> 
> 
> 
> 


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RE: [ECOS] FAT32 over NAND

[Chris Zimman]

> > YAFFS2 is not a possible option...As device should also be able to
> > access on Windows PC using mass storage interface...

You could build a FAT emulation layer in memory and map the calls through to
YAFFS2, but that's a non-trivial task.

> Is this a raw flash? So, how is it going to be accessed from Windows if
> the file system is completely in software?

Windows basically wants to treat NAND (eg. SD) just like any other disk and
wants to deal with it as sectors.
There's a minimal amount of glue necessary between the given SD interface and
eCos's disk layer.  Then you just have to 
[have/get/write] a USB mass storage endpoint driver.

Where you're going to run into trouble is if you have the device accessing
the file system at the same time that the PC (eg. Windows) is trying to.
The FAT tables are cached on Windows, and if you go change them from the
device side underneath Windows (eg. eCos app modifies file system while it's
mounted on Windows), 
you are heading for disaster.  The reason I raise this issue is because you
mentioned wanting both your device and Windows to be able to see the same
file system.

--Chris

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Re: [ECOS] FAT32 over NAND

[Jonathan Larmour]

Andrew Lunn wrote:
> On Tue, Jan 20, 2009 at 08:41:35PM +0530, Himanshu Patel wrote:
>> Okay...Thanks...
>>
>> YAFFS2 is not a possible option...As device should be able to access from PC
>> running Windows also through mass storage interface...
>>
>> Can we make use of NFTL (NAND flash translation layer) which Linux is
>> providing? 
> 
> Depends on what license you want to use. If you are happy that your
> entire system, is GPL, yes. However most people want to keep there
> application closed, in which case you cannot use Linux kernel code.

There are also patent issues. FTLs are covered by patents by M-Systems,
Inc. in the US and Europe at least. You cannot develop or sell a product
containing an FTL in those markets without getting a licence from M-Systems
(unless it's used in a PCMCIA device, for which M-Systems grants a
no-royalty licence).

See the bottomr of http://sources.redhat.com/jffs2/jffs2-html/node1.html

Because of this, I doubt eCos will ever have an FTL.

Jifl
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Barnwell House, Barnwell Drive, Cambridge, UK.       Tel: +44 1223 245571
Registered in England and Wales: Reg No 4422071.
------["Si fractum non sit, noli id reficere"]------       Opinions==mine

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RE: [ECOS] FAT32 over NAND

[Paul D. DeRocco]

> From: Jonathan Larmour
>
> There are also patent issues. FTLs are covered by patents by M-Systems,
> Inc. in the US and Europe at least. You cannot develop or sell a product
> containing an FTL in those markets without getting a licence from
> M-Systems
> (unless it's used in a PCMCIA device, for which M-Systems grants a
> no-royalty licence).

The SmartMedia specification, originally from May 1999, establishes a
standard for reading and writing SmartMedia cards, which are just single
NAND flash chips in a pluggable package, and it describes how a FAT16 file
system must map to the flash chip, by aligning the cluster boundaries to the
erasable block boundaries. There is no support for wear leveling beyond what
can be done while the power is turned on (i.e., maintaining a rover for
allocating the next block), and FAT16 is limited to 64K clusters which makes
it appropriate only for smaller sizes. Does the M-Systems patent cover any
translation layer one might write for a SmartMedia card?

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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Re: [ECOS] FAT32 over NAND

[Jonathan Larmour]

Paul D. DeRocco wrote:
>>From: Jonathan Larmour
>>
>>There are also patent issues. FTLs are covered by patents by M-Systems,
>>Inc. in the US and Europe at least. You cannot develop or sell a product
>>containing an FTL in those markets without getting a licence from
>>M-Systems
>>(unless it's used in a PCMCIA device, for which M-Systems grants a
>>no-royalty licence).
> 
> 
> The SmartMedia specification, originally from May 1999, establishes a
> standard for reading and writing SmartMedia cards, which are just single
> NAND flash chips in a pluggable package, and it describes how a FAT16 file
> system must map to the flash chip, by aligning the cluster boundaries to the
> erasable block boundaries. There is no support for wear leveling beyond what
> can be done while the power is turned on (i.e., maintaining a rover for
> allocating the next block), and FAT16 is limited to 64K clusters which makes
> it appropriate only for smaller sizes. Does the M-Systems patent cover any
> translation layer one might write for a SmartMedia card?

That implementation doesn't sound like an FTL, but then without things 
like wear-levelling or dealing with the inevitable bad blocks, it doesn't 
sound terribly useful either! I doubt that that conflicts with the patent. 
You could write a (non-standard) FTL that worked on top of it of course, 
but that's presumably not what you're talking about.

Jifl
-- 
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Barnwell House, Barnwell Drive, Cambridge, UK.       Tel: +44 1223 245571
Registered in England and Wales: Reg No 4422071.
------["The best things in life aren't things."]------      Opinions==mine

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RE: [ECOS] FAT32 over NAND

[Paul D. DeRocco]

> From: Jonathan Larmour
>
> That implementation doesn't sound like an FTL, but then without things
> like wear-levelling or dealing with the inevitable bad blocks, it doesn't
> sound terribly useful either! I doubt that that conflicts with
> the patent.
> You could write a (non-standard) FTL that worked on top of it of course,
> but that's presumably not what you're talking about.

It is an FTL, if I understand the term correctly. To the higher levels, the
device looks like a regular disk capable of supporting a FAT16 file system,
the only restriction being that the "disk" has to be formatted so that the
cluster size matches the erasable block size, and their boundaries have to
line up.

Underneath, it uses a RAM-based lookup table to map clusters to blocks, but
since FAT16 can't have any more than 64K clusters, the table can never
exceed 128KBytes. The mapping info is stored in the extra 16 bytes that
accompany every 512 byte page or "sector", along with a Hamming code that
can correct any single-bit error and detect most higher errors.

It deals with bad blocks by only allocating 1000 out of every 1024 blocks,
leaving the remaining 24 as spares, and it has a way of marking blocks free
(unused), dirty (needs erasure), bad (never to be used again), or allocated
to a particular location. If the software always searches for a free block
just past the last block that it found, then wear tends to be leveled
statistically, as long as the power stays on, but there is no usage count
recorded in the flash that forces precise leveling. But nowadays, flash
memories are so damn good that such a system works just fine for any but the
busiest applications. For instance, in a camera, it's doubtful that any
particular block will get erased and rewritten 100,000 times.

The SmartMedia spec was developed and owned by Toshiba, and launched in 1995
according to Wikipedia. It's now completely obsolete, but since it consisted
of a single NAND flash chip with no controller, the software needed to talk
to a SmartMedia card is still useful if you want to solder a single NAND
flash chip to a board, and run a FAT16 file system on it.

It's possible that SmartMedia does use M-Systems' patent, and that Toshiba
licensed it, because in order to obtain the SmartMedia spec, you had to buy
it, and I recall it wasn't particularly cheap. But if that's true, then
merely knowing how to write the necessary translation layer (which I know
because I wrote one years ago for a company that bought the spec) wouldn't
give you the right to put it into a product. That's what I'm curious about.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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Re: [ECOS] FAT32 over NAND

[Rutger Hofman]

Sorry to prod, but to answer you appropriately it would be helpful if 
you answer the question below:

Rutger Hofman wrote:
> Is this a NAND memory smart-card (MMC, SD, USB flash drive or whatever)? 
> These usually come with an FTL on-board, which offers a file system like 
> FAT32. You need no Flash code for that.
> 
> Is this a raw flash? So, how is it going to be accessed from Windows if 
> the file system is completely in software?

Can you please explain the type of NAND flash you want to use? Is this 
raw flash chips? Or is this a NAND memory 'card' of some type like 
listed above?

Rutger

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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Hi,

This will be raw NAND flash. 

There are two ways we want to access file system written on NAND flash:
1 Through PC
  PC will make use of the file system using mass storage driver.
2 Through device itself
  Device (uC) should be able to access read/write files from NAND flash.

Hope I have given the answers you are looking at. If not please free to ask.

Regards,

Himanshu Patel

-----Original Message-----
From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
Sent: Wednesday, January 21, 2009 7:33 PM
To: Himanshu Patel
Cc: 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

Sorry to prod, but to answer you appropriately it would be helpful if 
you answer the question below:

Rutger Hofman wrote:
> Is this a NAND memory smart-card (MMC, SD, USB flash drive or whatever)? 
> These usually come with an FTL on-board, which offers a file system like 
> FAT32. You need no Flash code for that.
> 
> Is this a raw flash? So, how is it going to be accessed from Windows if 
> the file system is completely in software?

Can you please explain the type of NAND flash you want to use? Is this 
raw flash chips? Or is this a NAND memory 'card' of some type like 
listed above?

Rutger




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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Hi,

This will be raw NAND flash. 

There are two ways we want to access file system written on NAND flash:
1 Through PC
  PC will make use of the file system using mass storage driver.
2 Through device itself
  Device (uC) should be able to access read/write files from NAND flash.

Hope I have given the answers you are looking at. If not please free to ask.

Regards,

Himanshu Patel

-----Original Message-----
From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
Sent: Wednesday, January 21, 2009 7:33 PM
To: Himanshu Patel
Cc: 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

Sorry to prod, but to answer you appropriately it would be helpful if 
you answer the question below:

Rutger Hofman wrote:
> Is this a NAND memory smart-card (MMC, SD, USB flash drive or whatever)? 
> These usually come with an FTL on-board, which offers a file system like 
> FAT32. You need no Flash code for that.
> 
> Is this a raw flash? So, how is it going to be accessed from Windows if 
> the file system is completely in software?

Can you please explain the type of NAND flash you want to use? Is this 
raw flash chips? Or is this a NAND memory 'card' of some type like 
listed above?

Rutger




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RE: [ECOS] FAT32 over NAND

[Himanshu Patel]

Hi,

This will be raw NAND flash. 

There are two ways we want to access file system written on NAND flash:
1 Through PC
  PC will make use of the file system using mass storage driver.
2 Through device itself
  Device (uC) should be able to access read/write files from NAND flash.

Hope I have given the answers you are looking at. If not please free to ask.

Regards,

Himanshu Patel

-----Original Message-----
From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
Sent: Wednesday, January 21, 2009 7:33 PM
To: Himanshu Patel
Cc: 'eCos Discuss'
Subject: Re: [ECOS] FAT32 over NAND

Sorry to prod, but to answer you appropriately it would be helpful if 
you answer the question below:

Rutger Hofman wrote:
> Is this a NAND memory smart-card (MMC, SD, USB flash drive or whatever)? 
> These usually come with an FTL on-board, which offers a file system like 
> FAT32. You need no Flash code for that.
> 
> Is this a raw flash? So, how is it going to be accessed from Windows if 
> the file system is completely in software?

Can you please explain the type of NAND flash you want to use? Is this 
raw flash chips? Or is this a NAND memory 'card' of some type like 
listed above?

Rutger




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RE: [ECOS] FAT32 over NAND

[Chris Zimman]

> This will be raw NAND flash.
> 
> There are two ways we want to access file system written on NAND flash:
> 1 Through PC
>   PC will make use of the file system using mass storage driver.
> 2 Through device itself
>   Device (uC) should be able to access read/write files from NAND
> flash.
> 
> Hope I have given the answers you are looking at. If not please free to
> ask.

As pointed out yesterday, if you try to treat this as a removable mass
storage device you will need to make 
sure that these two things don't happen at the same time (eg. device *must*
be unmounted from Windows -- or 
Linux or OSX or whatever) using FAT or you are going to end up in trouble.
Even read-only from the device 
side won't always work reliably since PC operating systems generally cache
access to the file system and do 
the writes batched.

If you can assure that Windows (or whatever) and the uC never access the
device at the same time (I don't 
mean protecting via a mutex or something like that), I mean the uC never
accesses the file system while the 
device is connected to a PC) then you can probably get away with this.  If
not, the FAT32 solution is not 
going to work well.

--Chris



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Re: [ECOS] FAT32 over NAND

[Rutger Hofman]

Hmmm. I am not familiar with 'mass storage driver'. I assume that it is 
a generic Windows thingy for block devices -- I know nothing about 
Windows? Or do you mean USB? If you do not mean USB, how is Windows 
going to access the device? Through some network? a bus? some other means?

If it goes through USB, I guess you need the uC to intermediate between 
USB and the Flash chips. In that case, there are possibilities besides 
FAT32.

Rutger

Himanshu Patel wrote:
> Hi,
> 
> This will be raw NAND flash. 
> 
> There are two ways we want to access file system written on NAND flash:
> 1 Through PC
>   PC will make use of the file system using mass storage driver.
> 2 Through device itself
>   Device (uC) should be able to access read/write files from NAND flash.
> 
> Hope I have given the answers you are looking at. If not please free to ask.
> 
> Regards,
> 
> Himanshu Patel
> 
> -----Original Message-----
> From: Rutger Hofman [mailto:rutger@cs.vu.nl] 
> Sent: Wednesday, January 21, 2009 7:33 PM
> To: Himanshu Patel
> Cc: 'eCos Discuss'
> Subject: Re: [ECOS] FAT32 over NAND
> 
> Sorry to prod, but to answer you appropriately it would be helpful if 
> you answer the question below:
> 
> Rutger Hofman wrote:
>> Is this a NAND memory smart-card (MMC, SD, USB flash drive or whatever)? 
>> These usually come with an FTL on-board, which offers a file system like 
>> FAT32. You need no Flash code for that.
>>
>> Is this a raw flash? So, how is it going to be accessed from Windows if 
>> the file system is completely in software?
> 
> Can you please explain the type of NAND flash you want to use? Is this 
> raw flash chips? Or is this a NAND memory 'card' of some type like 
> listed above?
> 
> Rutger
> 
> 
> 
> 


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RE: [ECOS] FAT32 over NAND

[Paul D. DeRocco]

> From: Rutger Hofman
>
> Hmmm. I am not familiar with 'mass storage driver'. I assume that it is
> a generic Windows thingy for block devices -- I know nothing about
> Windows? Or do you mean USB? If you do not mean USB, how is Windows
> going to access the device? Through some network? a bus? some other means?
>
> If it goes through USB, I guess you need the uC to intermediate between
> USB and the Flash chips. In that case, there are possibilities besides
> FAT32.

Although Himanshu hasn't said so explicitly, I infer that they've got a
board with a NAND flash soldered onto it, with an external interface like
USB, as opposed to Ethernet. If the interface is USB, then FAT is the _only_
choice, because USB presents a block-oriented interface, not a file-oriented
interface. And since any external device will be writing in the FAT file
format, an FTL designed specifically for FAT is needed.

If the design isn't cast in stone yet, one possibility is to put an SD
controller on the board. This eliminates the need for an FTL, requiring only
a minimal software interface between the external USB interface and the SD
controller. For small quantities, one might even consider putting a complete
SD socket and card on the board, even if it's not accessible outside the
box, since they're pretty cheap. Then, in development, one can pull the card
out and write to it on another machine, before the USB interface is even
working.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com


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