Re: [iPAQ] strongarm usb networking and Windows.

> In all the traffic I have seen regarding USB networking with an iPaq, there
> is always the requirement for a Linux box as the master (and The SA1110 is
> only a slave).
>
> Our arm-linux strongarm products are being prototyped on h3150/h3600s and
> could use occasional network connectivity. It is a breeze to set up a Telnet
> session into a lightly loaded h3150 from a Linux PC.
>
> USB networking is such a useful facility that it seems surprising that there
> is no talk of a Windows USB network adaptor driver along the same lines as
> the Linux one. Is there none available for Windows or have I just failed to
> uncover it?

I have been unable to find a standard Windows driver that can be coaxed into
playing with the StrongArm.

The main problem is the lack of an Interrupt endpoint.

> From poking around the 'net, it looks like what we'd need is a 'Remote
> NDIS' driver that speaks usbnet protocol to the ipaq. What currently
> happens on the windows end when you plug a lipaq in? Does it grab the
> usb device id and try to load drivers to do activesync over USB?

Yes, it is exactly what is required, but Microsoft interprets one paragraph
of the USB Class CDC specification as a requirement for an Interrupt endpoint.
So they don't support any hardware that does not have an Interrupt endpoint for
their RNDIS USB driver.

Commercial projects (like the Sharp Zaurus) are licensing a pair of NDIS/WDM
drivers from MCCI that have been adapted to not require anything other than
what the StrongArm has available. These work with GPL'd USB Device drivers
for linux done by Lineo.

It would in theory be possible to build Windows driver that would work
with the StrongArm. Especially if you only did a serial emulation. That
can be done in a single WDM driver. But getting any performance out of
PPP over serial over USB is difficult. Perhaps 60kbytes/second.

Doing a network driver in Windows requires NDIS, which is next to
impossible to use in a WDM driver. So you end up having to build two
drivers that talk to each other (which is what MCCI does, and Microsoft
does for their RNDIS driver). This can get you much better performance
(up to 750kbytes/second, still not as good as 850kbytes/second to a
Linux host though).

You then end up having to make the above work in five versions of
Windows each with their little quirks...

-- 
sdjl@fireplug.net