Caisson wrote:
>
> > Van: fcembrola <fcembrola@BTINTERNET.COM>
> > Aan: PICLIST@MITVMA.MIT.EDU
> > Onderwerp: I'm stuck with ISP problem
> > Datum: zondag 24 mei 1998 18:50
> >
> > Hi folks!
> >
> > I'm sorry for bringing this subject up again,
> > but I need some help in trying to
> > understand what's going on here.
> >
> > I constructed a cable which connects my
> > PICSTART16B, via a home-made socket,
> > to my project, in order to do in-circuit
> > programming.
> >
> > When I try to program the PIC (16C84), I find
> > that the first location is being programmed
> > with the second byte of the program, the
> > second location with the third byte... and so
> > on.
> >
> > Even more strangely it verifies ok.
> >
> > This is consistent. Therefore I have to
> > assume that the cable is correct.
> >
> > I need a clue why this is happening.
> > Help!!!!!!
> >
> >
> > Francesco Cembrola
>
> As others already pointed out, the rise-time of the MCLR puls is too long.
> This wil enable the oscilator to work and to execute the first
> program-step.
> After this, your MCLR has risen enough to be accepted as Program-voltage.
> Your PC stopped at adres 0x0001 - Your first byte wil put here and so on
> ..
>
> Solution :  Pull pin 16 (Osc1/ClkIn) to Ground (using a resistor) while
> programming. No clocks can be generated this way.
>
> Greetz,
>   Rudy Wieser
Interesting ! The Pic 16C74/73 had exactly the opposite problem:
microchip recommended a small capacitor between VPP and ground to LIMIT
the vpp rise time. Rumour has it that the initial 12C671s were delayed
due to a VPP rise time problem causing PICSTART PLUS incompatibility.
regards,
Graham Daniel