Bob,

in that case mux is better choice how about VPP do I need to turn off on ea=
ch=20
ICSP?.
thanks for your replay.=20

Andre




________________________________
From: Bob Ammerman <rvammerman@roadrunner.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sent: Mon, June 6, 2011 9:47:42 AM
Subject: Re: [PIC]:  question about PIC VPP

If I understand you correctly you are trying to use the PIC24 as a=20
demultiplexor for the ICSP clock and data lines. This is very unlikely to=20
work for at least a couple of reasons:

1: Timing. The ICSP clock and data lines change state very quickly. It is=20
unlikely that code running on the PIC24 will be able to copy the input valu=
e=20
to the output without messing up the timing.

2: Bidirectional. The ICSP data line is bidirectional. At some points the=20
programmer is driving it, at others the chip being programmed is driving it=
..=20
You would have to know which way to copy your data, which is, in general,=20
pretty close to impossible.

You might have a bit more luck using analog mux'es, but I'd even question=20
the likelihood of getting that to work.

-- Bob Ammerman
RAm Systems


----- Original Message -----=20
From: "Andre Abelian" <abelian.andre@yahoo.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Monday, June 06, 2011 12:28 PM
Subject: [PIC]: question about PIC VPP


> Hi all,
>
> I have PM3 programmer and I am making 12 ICSP connectors to program pic
> sequently.
> since the programmer has a connector to control every thing my question i=
s=20
> the
> fallowing:
>
> 1. I added transistor to switch on/off each pic VPP pin. lets say ICSP1=20
> vpp is
> connected to
>    PM3 and all other are off after done will switch next etc. my question=
=20
> is
> can I connect all VPP
>   together without turning them off? only use data and clock to program?.=
=20
> I
> know VPP carry 12v to put pic in programming mode
>   but is it safe to leave all of them connected together without switchin=
g=20
> them
> off?
>
> 2. how can I program parallel? how does it work?
>
> 3. if I use PIC to move programming data from one pin to another data and=
=20
> clock
> is it ok instead  of switching using like
>   analog switch etc.
>
> my main schematic looks like this. the programmer is connected to pic24=20
> and each
> ICSP connector is connected to pic pins
> and data and clock is bypassed in software and VPP I put fets to turn the=
m=20
> off
> separately.
>
> any suggestion?
>
> thanks
>
> Andre
> --=20
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist=20

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.