[hpsdr] FW: hpsdr] [FPGA_USB] Review/Comments FPGA_USB Board -April 5, 2006

[Christopher T. Day]

Phil,

Phil H. has already confirmed this, but the PIC is a general USB device;
how it appears to USB depends on the endpoint descriptors you program
into it. Presumably it comes with a COM device descriptor already there,
but that doesn't mean we have to stick with it.

This PIC device only goes up to Full Speed, not High Speed.

Well, this is a hobby, so I get to ride my hobby horse. Besides,
Isochronous Mode is _required_ for USB Audio Devices by the spec at
www.usb.org. I presume that means that any commercial USB audio box with
a logo _must_ be using Isochronous Mode; what I see in the Microsoft
Audio Device documentation seems to support that view. There is a lot
more involved than just the transfer speed; there is a lot of assumed
endpoint architecture as well.

Besides, it's my dead hobby horse and I intend to beat it. :)


	Chris - AE6VK


-----Original Message-----
From: Philip Covington [mailto:p.covington at gmail.com] 
Sent: Thursday, April 13, 2006 6:20 AM
To: Christopher T. Day


I know this was addressed to Phil H, but here are a few questions:

[WARNING I've not looked at the 18F4450 at all so this might be stupid]

Does the PIC look like a COM port because of its driver?  Could we use
something like libUSB to talk to the PIC and avoid loading its
supplied driver?  Just some thoughts...

Also, as far as Iso mode, with high speed USB the preferred method is
most always block transfers.  Iso was more important for USB 1.1.

73 de Phil N8VB


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