USB slave on a PC

Started by Jason Curl October 26, 2004
Hello,

I have a small PC104 device with one USB port. As of yet, I'm not too 
familiar with USB, except to know there is exactly 1 master and many slaves.

I would like to know if it is possible to make the PC104 device look 
like a slave, so that I can have it emulate a "usb storage device".

It's used for a logger, and eventually I'll insert a harddrive (instead 
of the now current flash card). By plugging it directly into a PC, I 
want to see the contents of the harddrive.

Any pointers would be extremely useful.

Thanks,
Jason.
There are some PC104 boards or COM modules that have both USB master AND 
slave ports. For example see www.compulab.co.il, ARMCore series.

Cheers,
Robert

"Jason Curl" <j_dot_curl_at_motorola_dot_com@foo.bar> a &#2013265929;crit dans le 
message de news: clm49k$7ch$1@newshost.mot.com...
> Hello, > > I have a small PC104 device with one USB port. As of yet, I'm not too > familiar with USB, except to know there is exactly 1 master and many > slaves. > > I would like to know if it is possible to make the PC104 device look like > a slave, so that I can have it emulate a "usb storage device". > > It's used for a logger, and eventually I'll insert a harddrive (instead of > the now current flash card). By plugging it directly into a PC, I want to > see the contents of the harddrive. > > Any pointers would be extremely useful. > > Thanks, > Jason.
Am Tue, 26 Oct 2004 20:13:43 +0200 schrieb Jason Curl:

> Hello, > > I have a small PC104 device with one USB port. As of yet, I'm not too > familiar with USB, except to know there is exactly 1 master and many slaves. > > I would like to know if it is possible to make the PC104 device look > like a slave, so that I can have it emulate a "usb storage device". > > It's used for a logger, and eventually I'll insert a harddrive (instead > of the now current flash card). By plugging it directly into a PC, I > want to see the contents of the harddrive. > > Any pointers would be extremely useful. > > Thanks, > Jason.
There are several USB Link cables available. Maybe you can "abuse" one of them for this? Alexander
Alexander Peter <apeter@musicandsales.com> wrote:

> There are several USB Link cables available. Maybe you can "abuse" one of > them for this?
I rather strongly doubt that. A link cable may be able to take of low-level (physical and link layer) differences between USB master and slave nodes, but they rely on specialized drivers for the rest of the job. They need specialized drivers on both ends (so you're most likely dead in the water unless your PC104 runs Windows >= ME/2000), and those drivers quite certainly won't be emulating harddrives --- they simulate network adapters instead. -- Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de) Even if all the snow were burnt, ashes would remain.
"Jason Curl" <j_dot_curl_at_motorola_dot_com@foo.bar> wrote in message
news:clm49k$7ch$1@newshost.mot.com...
> Hello, > > I have a small PC104 device with one USB port. As of yet, I'm not too > familiar with USB, except to know there is exactly 1 master and many
slaves.
> > I would like to know if it is possible to make the PC104 device look > like a slave, so that I can have it emulate a "usb storage device".
You can, but I don't know of any drivers available that will make the PC easily look like a storage device. It might be easier to get one of those "connect two PCs together as a two-point network" USB bridges and treat the PC104 as a network device, and run an FTP server on it or whatever. Richard [in PE12]
"Alexander Peter" <apeter@musicandsales.com> wrote in message

> There are several USB Link cables available. Maybe you can "abuse" one of > them for this?
That's not an abuse: that's what they're for (I assume you mean the PC-PC bridges, and not the b*stardisationed A-A cables, which violate the USB topology) Richard [in PE12]
Alexander Peter <apeter@musicandsales.com> wrote:

> There are several USB Link cables available. Maybe you can "abuse" one of > them for this?
I rather strongly doubt that. A link cable may be able to take care of the low-level (physical and link layer) differences between USB master and slave nodes, but these gadgets rely on specialized drivers for the rest of the job. They need specialized drivers on both ends (so you're most likely dead in the water unless your PC104 runs Windows >= ME/2000), and those drivers quite certainly won't be emulating harddrives --- they simulate network adapters instead. -- Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de) Even if all the snow were burnt, ashes would remain.
"Alexander Peter" <apeter@musicandsales.com> wrote in message
news:1l6rmca7xk3f3.i55jmqs03ect$.dlg@40tude.net...
> Am Tue, 26 Oct 2004 20:13:43 +0200 schrieb Jason Curl: > > > Hello, > > > > I have a small PC104 device with one USB port. As of yet, I'm not too > > familiar with USB, except to know there is exactly 1 master and many
slaves.
> > > > I would like to know if it is possible to make the PC104 device look > > like a slave, so that I can have it emulate a "usb storage device". > > > > It's used for a logger, and eventually I'll insert a harddrive (instead > > of the now current flash card). By plugging it directly into a PC, I > > want to see the contents of the harddrive. > > > > Any pointers would be extremely useful. > > > > Thanks, > > Jason. > > There are several USB Link cables available. Maybe you can "abuse" one of > them for this? > > Alexander
The USB device (slave) tends to have quite a simple driver. The host (master) very complex. They are two distinct pieces of hardware, although some chips have both device and host interfaces it is unlikely that the PC104 with have the device part wired up. You cannot just swap around cables to achieve this, and doing so can cause problems as the cable contains power. You need to get a USB device (slave) driver chip or specific device side interface card. Philips make some drivers with a simple i2c interface that I have used successfully in the past. Maybe you could knock something up using one of those? Richard. http://www.FreeRTOS.org