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Message
From: hannes.riedenbauer at lycos.de<hannes.riedenbauer@l...>
Date: Tue May 6 08:44:34 CEST 2008
Subject: [usb] USB 1.1 - resize FIFO
Hello,I have seen the USB1.1 implementation on opencores.org and I'm quite
happy with it. But I have some questions if you had time, please
answer me.
Because in my project the size of the core is more important than
speed im trying to minimize the area of the core. As I have seen most
impact have the FIFOs. So I wanted to implement only 8 Byte FIFOs
instead of 64 Byte. But when I resize the FIFOs to 8 Byte the tests
from your testbench fail because an error FIFO full is rising.
Is this a bug, or have I forgotten to reset some other variables?
At first I only changed the call of the FIFOs from:
generic_fifo_sc_a #(8,6,0) u10(
generic_fifo_sc_a #(8,6,0) u11(
to
generic_fifo_sc_a #(8,3,0) u10(
generic_fifo_sc_a #(8,3,0) u11(
. Then I reconfigured the descriptors in usb1_rom.v. But this was also
not enough.
Is it basically possible to expect a payload size from 53 bytes in the
call data_in, or a wLength of 53 in the send_setup call, with a FIFO
size of 8 Byte? I think it should work, but as told before I get
errors. I need this for reading the configuration descriptor or can I
read this then only in portions of 8? If yes, how can I read in
portions of 8? If I tried always got only the first 8 bytes.
If you have no time to answer the question it would be nice if you
only answer that you don't have time to answer the question. ;)
Thanks in advance.
Best regards,
Hannes Riedenbauer
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