Lpc2000

--- In lpc2000@yahoogroups.com, "mjbcswitzerland" 
<mjbcswitzerland@y...> wrote:
> --- In lpc2000@yahoogroups.com, "embyy27" <em3yy@e...> wrote:
> > 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.
> 
> 
> I am using the LPC2106 - is this note valid for this type too?

Not specifically, but you should still need to pay attention to the 
states of P0.14, DBGSEL, and RTCK during the watchdog reset.
 
 
> > Assuming state of these pins is OK, I had the followin thoughts:
> > 
> > You say that you have to cycle the power to recover.
> > 
> > Did you try activating the Reset pin without removing power?
> 
> I am using a simple external brown-out detector without reset 
> capability (no push button required) therefore I have to cycle the 
> power for a reset. When I get a chance I will verify that the 
> hardware is not locked up.
> 

You should be able to test this by just momentarily jumpering the 
RESET pin to ground.  (I assume that the output of your reset/brown-
out chip is short circuit protected.)

As to your earlier question: "In short - is the internal one
of real use in a critical application?," I believe it is not.

In addition to the processor always starting up with reset disabled 
(as you have noted), there is also no protection for over-writing the 
WDTC register (as someone else noted). Writing 0xFFFFFFFF to this 
register would give a watchdog time greater than 19 minutes for a 
typical 14.7456 MHz pclk - vitually worthless in most applications.

I don't understand why Philips bothered to protect the WDEN and
WDRESET bits without protecting the WDTC register!