I designed a circuit using a PIC12C509A and a capacitive power supply,
RC-network with two zener diode 12V
0.4W, and cap 100nf and 7805 and 100nf (for filter), always correct work
100%.
I think that your problem is noise in power supply or not write in program:

;**********************************************************************
;    Filename:     reasmf3.asm                                        *
;    Date:         18.01.2001.                                        *
;    File Version: 07.05.2001                                         *
;                                                                     *
;    Author:       POZNIC GORAN                                       *
;    Company:      ELBA                                               *
;**********************************************************************
;    PREMA SHEMI                                                      *
;               reasm3.pcb                                            *
;               reasm3.sch                                            *
;**********************************************************************

 list      p=12c509a           ; list directive to define processor
 #include <p12c509a.inc>       ; processor specific variable definitions

 __CONFIG   _CP_OFF & _WDT_ON & _MCLRE_OFF & _IntRC_OSC    <<<<<<<<<< THIS

If your problem insolvent, translate me your asm file pgoran@elba-sp.co.yu

Goran.


----- Original Message -----
From: "Marcelo Yamamoto" <m_yamamoto@UOL.COM.BR>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, June 27, 2001 6:22 PM
Subject: [PIC]: Internal RC osc problems...


> Roman,
> I designed a circuit using a PIC12C508A and a capacitive power supply. The
> rise time was very slow and sometimes the PIC did not start.
> I used all its 6 pins so have not some way to test an external Reset, but
I
> think the problem is the MCLR that does not resets the device properly.
> Using a small voltage regulador (78L05, TO-92 package), the power supply
> rise time gone faster and no fails until now (>10,000 devices running).
>
> Marcelo Y.
>
> Roman wrote:
> > Marcelo Yamamoto wrote:
> > >
> > > I had the same problem. 150ms is really very slow. Use a 78L05 to
supply
> the
> > > PIC and it should work.
> >
> >
> > Thanks Marcelo! Are you sure that is what it was?
> > Unfortunately my circuit is going to have a slightly
> > slow Vdd rise, the hardware design is finalised.
> >
> > I really didn't think the RC osc would be fussy with
> > Vdd rise... If you can offer any more info about your
> > experiences with this that would be great! :o)
> > -Roman
>
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>

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