Re: [usb] downgrade to USB1.1 low speed

[Rudolf Usselmann <rudi@asics.ws>]

On Sunday 24 February 2002 10:51 pm, you wrote:
> Hello all,
>
> I intend to downgrade USB 2.0 core of OpenCores to USB 1.1
> which will operate at Low and Full Speed rates. The reason
> is to enrich cores' variety of OpenCores and to enable mass
> testing of USB core in OpenCores community.
>
> Before I do that, I would like to know about your opinion. The
> most important is from Mr. Rudolf Usselmann, the USB 2.0 core
> creator. Also I knew from the project list that there is a USB host
> controller project and according to USB archive, it is also a
> function controller, not a host controller (p.s: I don't contact
> its maintainer yet...). Thanks...

Two suggestions:

1) There is no need to downgrade the core, as it will operate
in all three modes (low, full and high) just fine. I think it would
be a better idea to write a PHY that supports only low and full
speed modes instead. That way one could test the complete
solution at low and full speeds in an FPGA.

2) For only low and full speed, it might desirable to create a
different host interface. instead of using shared SSRAM, FIFOs
might be a better solution for many applications. It would be
nice to be able to select between the SSRAM and FIFO
interface.

As to the "USB Host controller" project, it's bogus. It's a function 
project as well, and the authors seem to have misunderstood
several important issues from the USB specification ... I have
emailed the authors but never got a reply, I have also asked
Damjan to remove the project, but that has not happened yet ...

Cheers,
rudi

> Best regard,
>
>
> RE Tambunan


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