Re: [ECOS] USB Help

[Andrew Lunn <andrew dot lunn at ascom dot ch>]

On Wed, Apr 16, 2003 at 09:43:20AM -0400, Patrick Doyle wrote:
> I am starting a project in which we are building a device that will, on
> occasion, need to connect to a Windows PC to download control and
> configuration information via USB.  Since I don't want to have to write (and
> maintain!) any windows device drivers, I thought I would make my device show
> up as a "standard" RS-232 USB device.  I was wondering...
> 
> 1) Is this feasible?
> 
> 2) Can anybody give me a good starting point to come up to speed quickly on
> USB?  (Right now, I can't even spell USB, but that will change rapidly.)
> 
> 3) The Windows application developers are all Java developers, and they are
> excited about the possibility of communicating with the device via COM7 (or
> whatever).  Is there a better approach that I should consider?
> 
> Any hints will be greatly appreciated.

Whats your target hardware? Experience with the StrongArm SA1110 and
the NEC Laki are that the USB devices have silicon bugs which make
writing drivers very hard. Don't underestimate the effort and make
sure you have good technical support from the chip set vendor, all the
Errata's and a USB analyzer.

USB support in eCos is in three layers. The lowest is hardware
drivers. The middle layer is hardware independent services, end
points, enumeration etc. The top layer is USB 'Applications'.  eCos
has support for Ethernet over USB as an application. It then becomes
possible to ping, ftp, etc to the target, just as if it had a real
ethernet device. There is a GPL Linux driver for this and Ascom
contracted another part of RedHat for Windows drivers. Not sure what
the license is on the RH M$ drivers.

Is RS-232 part of the HID? If so, M$ have probably implemented it to
the standard. Our experience with Ethernet is that everybody does it
there own way, so you need your own proprietary M$ drivers.

      Andrew



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