I haven't compared them with other available devices, but, you may want to
look at the national USBN9603/9604.  They have both parallel and SPI
interface capability, and they have a few nice things like a clock-out line
with internal programmable divider, which can be a plus.

However, as to overhead, the 9603/4 don't even do DATA0/DATA1 toggling for
you, though they do put them nicely in registers rather than making you
sort out the packet ID.

I don't know which would be better for your application but I thought that
you might want to know that there were also these out there.  From what you
describe, the 9603/4 that I'm using sounds reasonably similar to what you
have already found.


At 01:48 PM 19/12/2002 -0500, you wrote:
>I need to get a basic bi-directional byte stream via USB to/from an
>18F258, which will talk to a CAN bus and do a few other things.  I'm
>looking for advice or experience from people that have been this way
>before.
>
>Long winded background:
>
>So far I have found and read the data sheets for the Philips PDIUSBD12 and
>the Cypress SL811S.  Both these devices connect directly to the USB and
>provide an 8 bit parallel interface for control and data operations.
>
>Both seem to be rather low level in that they just pass on the control
>packets from the host and expect the micro to figure them out and respond.
>I was hoping I could set some state indicating which endpoints I was going
>to use how, the manufacturer's ID, etc, have the device automatically deal
>with all the USB BS, and just give me an input stream and an output
>stream.  There does not seem to be any device like that, so the firmware
>will have to handle this.  Oh well.

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