Hi, On Sat, 2011-01-01 at 12:51 -0500, Richard Sharpe wrote: > Firstly, I assume you are using the capability of the tools to > synthesize blockrams from largish arrays of 8/16/32-bit registers ... > is that the case? That seems to be the case from your definition of > softusb_dpram ...
Yes, this an elegant and portable way to generate RAM. See the "Coding style" section of the Xst user guide for more info on this (and ways to infer other design elements). > Secondly, I now understand more about how the soft USB functions since > I have checked out the external transceiver you are using ... but I > wonder if it is possible to use the ability of Spartan 3/6's to LVDS > to connect to USB without the transceiver you used? Perhaps the reason > that you used a transceiver is that USB uses 2,8-3.5v or something as > a high logic value which is more than the 2.5v LVDS handles? USB signaling isn't LVDS, but if the transceiver is a problem for you, you can simply use 3.3V LVCMOS I/O with some resistors in series. While it violates the USB specification, it happens to work on the couple of devices I tried that with. S. _______________________________________________ http://lists.milkymist.org/listinfo.cgi/devel-milkymist.org IRC: #milkym...@freenode Twitter: www.twitter.com/milkymistvj Ideas? http://milkymist.uservoice.com
