I don't seem to be able to find the change on opencores.org yet, do
you know when it's likely to pop up? Thanks again.
--- In "Jesse Off" <> wrote:
>
> --- In "fpga_test_dev" <fpga_test_dev@>
> wrote:
> >
> > I've been using the opencore code for some time, and getting random
> > sudden linux reboots after data transfers, but with the fix
> committed
> > on Dec. 13 I now seem to be able to transfer large amounts of data
> > without this happening.
> >
> > This has meant I've been able to write a little test program, which
> > just writes a word to the FPGA, then reads it back (to/from
> dummyreg).
> > The values written are just the index i, modulo 997. When I do
> this, I
> > get something like 1 or 2 errors every million words, where the
> value
> > read back is apparently always either 0 or 192 instead of the
> expected
> > value just written. e.g.:
> >
> > Incorrect: 4827 192 should be 839
> > Incorrect: 421369 0 should be 635
> >
> > (first number is the index of the word in the test, next number is
> the
> > actual value read back from FPGA, last number is the expected number
> > (the one written to FPGA))
>
> I actually just found another bug in the bridge since the Dec 13th
> fix. Unfortunately, it was very difficult to reproduce, very random,
> and seemed to be specific to each bitstream generated. 99% of the
> time in my experience these types of heisenbugs have been because of
> asynchronous logic or unexpected metastability. I don't use asynch
> logic often, but in this one case (wishbone bridge) I used it with 4
> flip-flops to make the bridge as fast as possible. Since ruling out
> metastability, I looked a little closer at the 4 flip-flops I was
> using asynch sets/clrs on and found the problem as a potential glitch
> on one of the flip-flop's asynch set signals.
>
> Lesson learned. Problem solved. Fix should be committed to
> opencores.org shortly.
>
> //Jesse Off
>
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/ts-7000/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/ts-7000/join
(Yahoo! ID required)
<*> To change settings via email:
<*> To unsubscribe from this group, send an email to:
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
|