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Message
From: Mark Bourne<dkglyp802@s...>
Date: Mon Dec 12 17:27:18 CET 2005
Subject: [usb] usb1_core Endpoint FIFO interfaces
The comments in usb1_core.v describe the IN/OUT FIFO interfaces as:> epN_din, epN_we, epN_full,
> This is the OUT FIFO interface. If this is a IN endpoint, ground
> all unused inputs and leave outputs unconnected.
>
> epN_dout, epN_re, epN_empty,
> this is the IN FIFO interface. If this is a OUT endpoint ground
> all unused inputs and leave outputs unconnected.
test_bench_top.v (when defining the connections to a usb1_core) contains:
> // End point 1 'OUT' FIFO i/f
> .ep1_dout( ),
> .ep1_we( ),
> .ep1_full( 1'b0 ),
> // End point 1 'IN' FIFO i/f
> .ep1_din( ep1_us_din ),
> .ep1_re( ep1_us_re ),
> .ep1_empty( ep1_us_empty ),
This seems to make more sense, in that d_out is associated with checking
if the FIFO is full, and enabling a write to the FIFO, while d_in is
associated with checking if the FIFO is empty and enabling a read from
the FIFO.
I have spent some time puzzling over the contents of usb1_core.v before
looking at the test benches, and don't know how many other people will
do the same. Maybe someone should correct the descriptions in
usb1_core.v? Anyway, I hope this will be useful to anyone having trouble
working out the interfaces.
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