Lpc2000

Hi there,
there is a note in the UM about the feeding sequence
of the PLL which says that the writing of 0xAA and
then 0x55 must be two consecutive VPB cycles. No
interrupts between them. For the WDT the text is
different it says that after feeding 0xAA "...the next
operation in the Watchdog register space should be a
WRITE (0x55) to the WDFEED register otherwise the
Watchdog is triggered."

May be the dog doesn't like to be interrupted when
feeding.
  
Regards

--- "Ake Hedman, eurosource" <akhe@...>
wrote:

> Hi all.
> 
> I am trying to enable the watchdog but the result is
> a total hang of the 
> board. Not even the bootloader is possible to reach
> after the crash and 
> I have to reapply power with P0.14 low to get access
> to the botloader 
> again. Reset is not enough.
> 
> The code to initialize the watchdog is
> 
>     // initialize the watchdog timer
>     WDTC = 0xffffffff; // 15000000;                 
>       // One second 
> = 15000000
>     WDMOD = WDEN | WDRESET;                    //
> Activate watchdog
>     WDFEED = 0xAA; WDFEED = 0x55;
> 
> I must have misunderstood the WD functionality. What
> am I doing wrong? 
> In the above code the watchdog should not trigger
> until 5 minutes 
> elapsed so even if a vector should be wrong the code
> that follow should 
> run for a while but as soon as I write to the WDMOD
> register I get a hang.
> 
> /Ake
> 
> -- 
>  ---
> Ake Hedman (YAP - Yet Another Programmer)
> eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
> Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
> Company home: http://www.eurosource.se      
> Kryddor/Te/Kaffe: http://www.brattberg.com
> Personal homepage: http://www.eurosource.se/akhe
> Automated home: http://www.vscp.org
> 
> 
> 



		
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