[filmscanners] RE: Off Topic: About those USB flashmemorydrives...

["Bob Aldridge" <Bob@ps.com>]

Basically, Art, for what you want to do, you have to connect a USB
"client"
to a USB "host". The "host" then does all the computing to direct the
traffic.

Unfortunately, both memory device and camera are USB "clients", so
neither is capable of directing the operations.

For what it's worth, my Toshiba pocket PC only has a client USB port,
whilst the more expensive ones have USB "hosts"...

Bob Aldridge

-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk] On Behalf Of Arthur Entlich
Sent: 17 February 2004 10:29
To: Bob@ps.com
Subject: [filmscanners] Re: Off Topic: About those USB
flashmemorydrives...

Hi Bob,

Thanks again for the explanation.

Since there seems to be not a lot of film scanner traffic I hope no one
is objecting to our discussion on the list.

This camera is designed to do a few things that may be relevant to this
discussion.  It is designed to work with a docking station (It's a HP
camera) and also to download directly to a HP printer without use of
either a computer "middleman" or having to remove the memory card.  You
can even tag the specific images you want to print, and indicate which
size to print it at, via the camera menus.

There is a section discussing the computer/camera interface.  In the
troubleshooting section it says:

Message on computer: Computer cannot find connected camera

Possible Cause: The camera is set to the Digital Camera setting "USB
configuration"  sub-menu, but the computer cannot recognize the camera
as a digital camera.

Solution: Change the USB Configuration setting to Disk Drive in the
Setup menu.  This allows the camera to appear as another disk drive on
the computer so that you can easily copy the image files from the camera
to the hard drive of your computer.

Now this may just be, as you stated, how the computer recognizes the
camera, because the manual further states that the Digital Camera option
causes the computer to use Picture Transfer Protocol, while setting it
to Disk Drive uses MSDC standard. (which can be used on computers which
do not have the camera drivers installed).

Anyway, it would be nice if the camera itself had et ability to initiate
the transfer and allow it to send data to these flash disk drives.

Art


Bob Shomler wrote:

>>One think I still don't quite understand.  My digital camera, as soon
as
>>it is attached to the USB port of my computer and turned on, obviously
>>communicates with the computer, because the LCD screen of the camera
>>reads "Communicating with computer" and the computer launches the
>>downloading software, and the download is both sent to the hard drive
>>and to a memory resident program, so I can see thumbnails of the
images
>>on the computer screen.
>>
>>Would there be no way to make the camera request info off the jump
drive
>>and then handshake and download the image data to it, or must a CPU be
>>controlling the communications back and forth?
>
>
> Hello Art.  So far as I know there would not be the ability for the
camera to do what you describe.  What you are seeing with the camera is
that when you plug it into the USB, that action causes the computer/host
side USB interface to recognize that there is new hardware on that USB
link.  It polls the link, discovers that the new HW is known to the
system, invokes the device driver identified with that camera (that
binding established when you installed the camera SW) and this driver
initiates I/O to the camera to establish communication.  It is while
this activity and related work is going on that the camera puts up the
"communicating with computer" message.  So you need something with host
SW capability (such as "CPU") to initiate the host-side activity that
establishes the camera-to-computer connection.
>
> Bob Shomler
>
>

------------------------------------------------------------------------
----------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message
title or body


----------------------------------------------------------------------------------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe 
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or 
body