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Message

Watchdog bites

2005-07-28 by Bruce Parham

All,

Thanks for all the comments on bogus op-codes. The boot loader code is about done.
I'm at the point of exiting the loader and starting the application code but haven't
decided which way to go. The original application code was done assuming that the cpu
would startup from a reset though it may work just fine using a jump to 0x0000.

I started playing with the watchdog timer in Studio sim and it does work but the timing
is way off vs the data sheet specs. Enabling the timer with the prescaler bits all clear
should result in a 14-15 ms timeout but Studio sim pops to the reset point in something
under 2 ms. This all may just be a sim bug, like SPM page erase and writes only taking
one clock cycle, no big deal. The other issue, and on this the data sheet says nothing,
is that the WD timer is still enabled after the timer triggered reset.

Does anybody have any insights as to how the real hardware does it? Is it still enabled
after a reset? If it is, I'll need to set the timer for a longer period to get through
the app startup.

Thanks in advance.

Bruce

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