On Wed, 23 Mar 2005, andygryc wrote:
>
>
> The manual has the following cryptic comment: "Do not attempt to use
> the Watchdog Timer in the EP9302".
>
> Now, I *am* using it, and it does not appear to have any ill effects
> when the watchdog resets. If I was to read into the comment, I'm
> guessing that the watchdog reset only resets the CPU and won't reset
> the PLD. However, since I don't appear to see any problems in doing
> this, I was wondering if someone could explain in just a tiny bit
> more detail what the consequences might be.
Early versions of the EP93xx silicon had issue with the watchdog on the
chip. What we had found in early prototyping/testing is that about 1 out
of 20-30 resets using the watchdog would lock up the processor instead of
reseting it. When we queried our contacts at Cirrus Logic they said "dont
use the watchdog", so we implemented the CPLD watchdog. About 2 months
later, they released the errata described at
http://www.cirrus.com/en/pubs/appNote/AN258REV2.pdf
Recent versions of silicon may (or may not) have issue with the watchdog,
but YMMV. We would be able to implement the features you would require on
the watchdog fairly easily, but unfortuntely we do not have even one spare
bit available on the CPLD.
//Jesse Off
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