James Padfield wrote:
>
> > > I thought LVP was disabled via the configuration word? I just modified
> >the
> > > NOPPP software so that I can use a NOPPP programmer to program a 16F628,
> >but
> > > haven't had chance to test it yet...
> >
> >As I understand it the problem is that erasing the chip (in HVP) erases the
> >configuration word, and after erasing you must cycle MCLR (or the chip
> >resets itself? I don't remember) and at that point LVP is in practice
> >enabled.
> >
> >Anyway, in my experience (YMMV) tying the LVP pin low is NOT needed for
> >16F877 HVP programming, but is IS needed for 16F628 HVP programming. To be
> >on the safe side, just tie the LVP pin low anyway.
>
> Ok, I tested it last night on my modified NOPPP software, the original
> hardware (ie. LVP pin *not* tied low) and with a 16F628. It programmed and
> verified the chip just fine, but I see something strange when plugging the
> chip into my board.
> I was testing with a simple LED flasher program. It works perfectly when run
> on a 16F84A, but the program seems to run slowly on the 16F628.
> I'll try and make that clearer. Using the 84A, the LED flashes every 0.5
> seconds, as it should. With the 628, the LED flashes about every 2.5
> seconds. I am using PicBasicPro, and the Basic source code is unchanged each
> time. Just when compiling I set it to compile for the appropriate PIC. Both
> PICs are 20MHz parts with a 20MHz crystal on the board.
> Any ideas what could be causing this?

LVP enabled on RB4, Comparators enabled??

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Best regards

Tony

mICros
http://www.bubblesoftonline.com
mailto:sales@bubblesoftonline.com

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