File System for "disk-on-key" device

[Alex Zaretsky]

Hello, everyone !
It's my first time here.
Really great resource.
I have one tiny question.
I will really appriciate if anyone can help me out with it.

We are developing a "camera on a stick".
It is actually a CMOS sensor camera with a very simple Micro controller
which supports the USB 2.0 protocol and MPEG2 encoder chip.
The idea is that the camera will compress rather small video clips in
MPEG2 format to the external "disk-on-key" (for example of M-Systems)
connected to the camera all the time during video capturing.
When the disk-on-key is inserted to a computer USB it should be
automatically accessable by Windows Explorer without installation of
any driver software.

The problem we face is how to support the Windows File system without
using high-end controllers (ARM for example) with an operating system
running on it. We are really interested in keeping the price of the
device as low as possible.

As far as I understand today every digital camera, every Voice
recorder, MP3 player with USB support faced the same problem.
Thank you very much.

Alex Zaretsky.

 

[Rene Tschaggelar]

We are developing a "camera on a stick".
It is actually a CMOS sensor camera with a very simple Micro controller
which supports the USB 2.0 protocol and MPEG2 encoder chip.
The idea is that the camera will compress rather small video clips in
MPEG2 format to the external "disk-on-key" (for example of M-Systems)
connected to the camera all the time during video capturing.
When the disk-on-key is inserted to a computer USB it should be
automatically accessable by Windows Explorer without installation of
any driver software.

The problem we face is how to support the Windows File system without
using high-end controllers (ARM for example) with an operating system
running on it. We are really interested in keeping the price of the
device as low as possible.

As far as I understand today every digital camera, every Voice
recorder, MP3 player with USB support faced the same problem.
Thank you very much.

Yes, then it is time to consider a USB host adapter chip.
It acts like a PC and aceesed the Flash sticks.
There is Cypress and the Atmel USB380 plus more.
the newsgroup comp.arch.embedded might also be more
appropriate. Look out for "USB host" there.

Rene

 

[[email protected]]

The problem we face is how to support the Windows File system without

Supporting FAT is not a big task and can easily be done in an 8-bit
microcontroller. The hard part is the USB stack. Better to pick a USB
host chip that has existing IP (maybe built-in). Look at Atmel's parts
for example, which are designed to solve this problem for you.

 

[Mark Jones]

Hello, everyone !
It's my first time here.
Really great resource.
I have one tiny question.
I will really appriciate if anyone can help me out with it.

We are developing a "camera on a stick".
It is actually a CMOS sensor camera with a very simple Micro controller
which supports the USB 2.0 protocol and MPEG2 encoder chip.
The idea is that the camera will compress rather small video clips in
MPEG2 format to the external "disk-on-key" (for example of M-Systems)
connected to the camera all the time during video capturing.
When the disk-on-key is inserted to a computer USB it should be
automatically accessable by Windows Explorer without installation of
any driver software.

The problem we face is how to support the Windows File system without
using high-end controllers (ARM for example) with an operating system
running on it. We are really interested in keeping the price of the
device as low as possible.

As far as I understand today every digital camera, every Voice
recorder, MP3 player with USB support faced the same problem.
Thank you very much.

Alex Zaretsky.

Hi Alex. I don't know if this will help you but here's another idea.
If you could record the data to a compact-flash memory card, they have
a nearly identical pinout and functionality to an IDE hard disk. Then
you only need an USB --> IDE interface, which have become so popular.

Cypress seems to make some nice USB micro hubs, one of these might be
worth checking out. See:
http://www.digikey.com/scripts/dksearch/dksus.dll?KeywordSearch&Keywords=Cypress+USB


-- "The knowledge is worth 10x more than the solution." MCJ 200401

 

[Rich Grise]

We are developing a "camera on a stick".
It is actually a CMOS sensor camera with a very simple Micro controller
which supports the USB 2.0 protocol and MPEG2 encoder chip.
The idea is that the camera will compress rather small video clips in
MPEG2 format to the external "disk-on-key" (for example of M-Systems)
connected to the camera all the time during video capturing.
When the disk-on-key is inserted to a computer USB it should be
automatically accessable by Windows Explorer without installation of
any driver software.

The problem we face is how to support the Windows File system without
using high-end controllers (ARM for example) with an operating system
running on it. We are really interested in keeping the price of the
device as low as possible.

FWIW, I have a Fuji "Fine-Pix A210" with USB, and whether I plug it into
Doze or Linux it just shows up as a drive. I have no idea what exact
filesystem it is, or if it even makes any difference; in Doze it just
shows up when I plug it in, with Linux, I have to mount it. So the OS has
whatever drivers it needs - all you have to do is deliver data to it,
I'd think.

Good Luck!
Rich

 

[Rene Tschaggelar]

FWIW, I have a Fuji "Fine-Pix A210" with USB, and whether I plug it into
Doze or Linux it just shows up as a drive. I have no idea what exact
filesystem it is, or if it even makes any difference; in Doze it just
shows up when I plug it in, with Linux, I have to mount it. So the OS has
whatever drivers it needs - all you have to do is deliver data to it,
I'd think.

Yes, since the PC, here Doze or Linux provides the USB driver.
The problems with these is writing to the USB stick from an
embedded systems where a USB host adapter is not trivial.
It is the USB part that is difficult, not the filesystem part.

Rene

 

[Rich Grise]

Yes, since the PC, here Doze or Linux provides the USB driver.
The problems with these is writing to the USB stick from an
embedded systems where a USB host adapter is not trivial.
It is the USB part that is difficult, not the filesystem part.

I had had the impression that they had access to the internals of the "USB
stick", and they were looking to write to that memory directly (not through
the USB) and then present that data through the USB port to the host.

Thanks for the clarification.

So, what you need to do is, sniff the USB line of the adapter plugged
into a PC, and then duplicate that.

Cheers!
Rich

 

[Alex Zaretsky]

Thank you all guys for such an interesting discussion.
I learned a lot from your notes.

1)
To Rich Grise and Rene Tschaggelar.
I don't really agree with you guys.
The data transferred through the USB protocol has to be arranged in a
certain way,
such that OS will be able to recognize it as a file, to separate data
belonging to two different files, to find files in the directories. All
these are under the responsibility of the File System (FAT or NTFS).
These issues have nothing to do with the PC's USB driver, which is only
responsible for data transfer.

2)
All this information regarding the USB host adapter chips is new for
me.
Thank you all for opening my eyes.
I just need to learn about it now in order to understnad exactly how
the File System problem is solved both for FAT and NTFS using this USB
host.

Thanks again.

Alex.

 

[John Larkin]

Thank you all guys for such an interesting discussion.
I learned a lot from your notes.

1)
To Rich Grise and Rene Tschaggelar.
I don't really agree with you guys.
The data transferred through the USB protocol has to be arranged in a
certain way,
such that OS will be able to recognize it as a file, to separate data
belonging to two different files, to find files in the directories. All
these are under the responsibility of the File System (FAT or NTFS).
These issues have nothing to do with the PC's USB driver, which is only
responsible for data transfer.

2)
All this information regarding the USB host adapter chips is new for
me.
Thank you all for opening my eyes.
I just need to learn about it now in order to understnad exactly how
the File System problem is solved both for FAT and NTFS using this USB
host.

Thanks again.

Alex.

Look up Open Dos and Freedos. Both have USB stacks for DOS, and
sources may be available. You might also google "USB DOS" and look for
stack sources.

John