Rudolf Ladyzhenskii wrote:
> USB is a master-slave system. Camera is a slave, so you need a master (USB 
> host). Low-end micros with USB are USB slaves too.
> 
> You need a USB host. It is either built into the higher-end processors or 
> you need external chip. But this is only half a problem. Then you need USB 
> host stack, typically found in larger OS, like Linux.

I'm solving this problem with a Linksys NSLU2 (Network storage system).
This device has one ethernet port, two USB host, and 1.5 serial ports.

You can load a version of Linux on it that will handle a webcam.

I am planning on preporoccesing the image there and then passing on
the relevent information to my main processor.

http://www.nslu2-linux.org/wiki/
--
D. Jay Newman
http://enerd.ws/robots/

USB is a master-slave system. Camera is a slave, so you need a master (USB 
host). Low-end micros with USB are USB slaves too.

You need a USB host. It is either built into the higher-end processors or 
you need external chip. But this is only half a problem. Then you need USB 
host stack, typically found in larger OS, like Linux.

Rudolf

"Ivan Nathvalski" <ivanNath@rotolmail.com> wrote in message 
news:4312df09$0$22557$afc38c87@news.optusnet.com.au...
> Can some USB, microcontroller expert advise me how can a USB webcam be 
> interfaced with a microcontroller (PIC, ATMega, etc) so that we can 
> capture image frames (low speed, low res) with the microcontroller?
>
>
>
> 

On Mon, 29 Aug 2005 20:11:02 +1000, "Ivan Nathvalski" <ivanNath@rotolmail.com> wrote:

>Can some USB, microcontroller expert advise me how can a USB webcam be 
>interfaced with a microcontroller (PIC, ATMega, etc) so that we can capture 
>image frames (low speed, low res) with the microcontroller?
>
> 
>

Not a USB solution, but John Orlando and Brent Taylor won 2nd prize
in Circuit Cellar's AVR contest last year with an ATmega8 controlled camera.
http://www.circuitcellar.com/avr2004/Second.html

"Ivan Nathvalski" <ivanNath@rotolmail.com> wrote in message 
news:4312df09$0$22557$afc38c87@news.optusnet.com.au...
> Can some USB, microcontroller expert advise me how can a USB webcam be 
> interfaced with a microcontroller (PIC, ATMega, etc) so that we can 
> capture image frames (low speed, low res) with the microcontroller?
>

Go with an older type serial cam or  get a camucam2 or avr cam
or similar.

http://www.cs.cmu.edu/~cmucam/
http://www.jrobot.net/

http://home.teleport.ch/idobson/   using bascom avr
http://home.teleport.ch/idobson/projects/UDP-webcam.htm
http://home.teleport.ch/idobson/start_e.htm

Alex 

Cypress makes some nice little USB host chips - I'd reccomend taking a
look at those as I doubt a 8b micro could handle the complexities of a
USB host interface. Best of luck!

-M. Noone

In comp.arch.embedded Ivan Nathvalski <ivanNath@rotolmail.com> wrote:
> Can some USB, microcontroller expert advise me how can a USB webcam be 
> interfaced with a microcontroller (PIC, ATMega, etc) so that we can capture 
> image frames (low speed, low res) with the microcontroller?

About as well as you could pull a 20-ton cargo trailer up a hill using
a bicycle.  You need a USB host for that, which needs between one and
two orders of magnitude more CPU power than what you're envisioning.

-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

"Ivan Nathvalski" <ivanNath@rotolmail.com> wrote in message 
news:4312df09$0$22557$afc38c87@news.optusnet.com.au...
> Can some USB, microcontroller expert advise me how can a USB webcam be 
> interfaced with a microcontroller (PIC, ATMega, etc) so that we can 
> capture image frames (low speed, low res) with the microcontroller?
Forget it.
Better just to buy one of the cameras with a video output.
Key thing about USB, is that it is designed to make the 'slave' device 
relatively easy to produce. The 'host' device, requires a _lot_ more 
hardware and code. It is possible to produce a basic host, but you are 
looking at perhaps 5 to 10* as much work as producing a direct video 
grabber...

Best Wishes 

> Can some USB, microcontroller expert advise me how can a USB webcam be 
> interfaced with a microcontroller (PIC, ATMega, etc) so that we can 
> capture image frames (low speed, low res) with the microcontroller?

you'd need a usb host on the board to interface with the micro, power to run 
the cam from the board... you may be better ripping a cheap cam apart and 
pulling a direct video output before the usb out (if possible)

-mark 

Can some USB, microcontroller expert advise me how can a USB webcam be 
interfaced with a microcontroller (PIC, ATMega, etc) so that we can capture 
image frames (low speed, low res) with the microcontroller?