According to the datasheet, there is no internal pull-up available at all in
the 12F675.
But this is supposed to be irrelevant as I want to program the chip NOT to
have or use MCLR as reset at all.
What i wonder is if the device could interpret static buildup on the pin as
VPP and halt operation.

Kyrre


----- Original Message ----- 
From: "Bob Axtell" <engineer@cotse.net>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Wednesday, March 09, 2005 8:10 PM
Subject: Re: [PIC]: MCLR and pullups on 12F675 ?


> Kyrre Aalerud wrote:
>
> >Hi guys.  I am having a bit of a design issue here.
> >Making a logger, I want to use GP3 (MCLR) on a 12F675 for both input and
> >ICSP thus needing to feed it 12v.
> >If I disable MCLR, do I still need to use a pullup on this pin to make
sure
> >my circuit starts reliably?
> >When the programmer isn't connected the pin would be floating, except for
> >when I offload my logger,
> >then it would be used as a TTL level input for serial data.
> >
> >Anyone got experience with this?
> >
> >Kyrre
> >
> >
> >
> >
> I'm pretty sure that if you were using the MCLR\ as reset, there is a
> internal pullup but
> since you are using as a signal input, you need to add an external R to
VDD.
>
> I'd use 22K-27K.
>
> --Bob
>
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