Check your power integrity. A brown out could cause this.=20
Larry Nelson Sr
Www.mchipguru.com

Perry Curling-Hope <perry741@gmail.com> wrote:

>I am using a PIC16F887 as a controller for a laboratory process.
>
>TMR1 is preloaded and allowed to timeout at 1sec a interval, the
>interrupt
>service routine then determines if the interrupt was caused by TMR1,
>and
>decrements a register containing a time countdown value, prompting the
>process to advance when the register reaches zero.
>
>The Watchdog period is slightly greater than 1 second, (to accomodate
>the
>rest of the code execution loop) and the watchdog is cleared within the
>interrupt service routine ( a watchdog light is toggled there as well)
>On an occurrence of a reset, the timeout in STATUS register bit4 is
>examined to determine if the reset was caused by the WDT, and the
>program
>redirected to resume execution in the correct place, else the normal
>power
>up initialisation and startup is executed.
>
>All works great....except....after some indeterminate period, varying
>from
>a couple of minutes to over 3 hours, the watchdog light stops and the
>LCD
>displaying the time countdown  'freezes', indicating that the micro has
>ceased executing the loop.
>One would expect that if the watchdog was not being serviced, a reset
>would
>ensue regardless and the machine would resume execution...somewhere.
>
>Not so....it appears 'dead', as if the LFINTOSC has ceased, which is
>not
>supposed to happen.
>Even a 'hard' reset applied to the MCLR/Vpp pin (which is enabled and
>effects an immidiate reset at all other times) does not restart the
>micro'.
>
>Only a complete power down and restart through powering up again will
>cause
>the microcomputer to resume operation
>
>Any ideas would be much appriciated.
>
>--=20
>Perry Curling-Hope
>
>Research and Development
>--=20
>http://www.piclist.com PIC/SX FAQ & list archive
>View/change your membership options at
>http://mailman.mit.edu/mailman/listinfo/piclist

--=20
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--=20
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