Lpc2000

--- In lpc2000@yahoogroups.com, "embyy27" <em3yy@e...> wrote:
> Did you ever get your watchdog reset problem resolved?

Yes and no.  I never figured out what was causing the reset failure,
but I was able to work around it:  The board is part of a larger
system, including an ARM9 XScale board running Linux.  The Linux
board requests a status report from the LPC2124 board every 10ms
(via RS232), and yanks the reset line if it doesn't get a response.

> Did you try activating the Reset pin without removing power?

Yes.  An external reset works fine.

> If your theory about the watchdog reset is correct, then activating
> the Reset pin should recover. If activating the Reset pin does not
> recover, then the problem is not the watchdog reset. Rather, the
> chip is getting into some sort of hardware latch-up which requires
> power cycling to recover - if that is true, adding an external
> watchdog (to trigger a reset) will not help you, unless you have the
> external watchdog toggle the power.

The external reset works, but the watchdog also works if I set
it to "Interrupt Only" (set WDMOD to 1 instead of 3).  That is
good enough for catching software loops or timing problems, and
the external monitoring will catch anything else.  So the problem
is solved as far as I am concerned, and I never spent any more
time investigating the underlying watchdog reset problem.

> See "USAGE NOTES ON WATCHDOG RESET AND EXTERNAL START" on page 214
> of the 2124 User Manual (Dated May 03, 2004). Does this solve your
> problem.

No.  This note only applies to LPC2212/2214.  I am using a LPC2124.

Btw, I only saw this problem on one board, and no one else was able
to reproduce the problem.  So it might have just been a bad chip or
a bad board.  I never tested for the problem on any other board.  I
can do some more testing if you are interested, since I now have
some new boards.

    -bob