Since the blank PIC doesn't know the type and configuration of its clock
until its programmed with that info, does that mean that a crystal or EXT CR
need not be present during programming?

TIA.

"ian field" <dai.ode@ntlworld.com> wrote in message
news:O6gbj.40321$wD5.19889@newsfe3-gui.ntli.net...
> Since the blank PIC doesn't know the type and configuration of its clock
> until its programmed with that info, does that mean that a crystal or EXT
> CR
> need not be present during programming?
>
> TIA.
>

Ian,

If you are thinking about in-circuit serial programming, you may want to
read Olin Lathrop's article here:
http://www.embedinc.com/picprg/icsp.htm

Also, the Microchip In-Circuit Programming (ICSP) Guide is available from
the Microchip site.

If you are thinking about a stand-alone programmer, then the PIC wouldn't
have anything connected to it, anyway.

Richard

ian field wrote:
> Since the blank PIC doesn't know the type and configuration of its clock
> until its programmed with that info, does that mean that a crystal or EXT CR
> need not be present during programming?
>
> TIA.
>
>
>

No clock needed for programming,it seems to be clocked from the
programmer lines (data,clock,Vpp[+13V])

"ian field" <dai.ode@ntlworld.com> wrote in message
news:O6gbj.40321$wD5.19889@newsfe3-gui.ntli.net...
> Since the blank PIC doesn't know the type and configuration of its clock
> until its programmed with that info, does that mean that a crystal or EXT
> CR
> need not be present during programming?
>
> TIA.
>
>

The pics default to the internal oscillator. There are default configuration
bits.

For programming the clock is external an supplied by the PGCx line. The data
is clocked in so the internal oscillator is not used(well, except for some
internal stuff but not for sending commands and receiving data.

"Jon Slaughter" <Jon_Slaughter@Hotmail.com> wrote in message
news:Jmvbj.677$El5.198@newssvr22.news.prodigy.net...
>
> "ian field" <dai.ode@ntlworld.com> wrote in message
> news:O6gbj.40321$wD5.19889@newsfe3-gui.ntli.net...
>> Since the blank PIC doesn't know the type and configuration of its clock
>> until its programmed with that info, does that mean that a crystal or EXT
>> CR
>> need not be present during programming?
>>
>> TIA.
>>
>>
>
> The pics default to the internal oscillator. There are default
> configuration bits.
>
> For programming the clock is external an supplied by the PGCx line. The
> data is clocked in so the internal oscillator is not used(well, except for
> some internal stuff but not for sending commands and receiving data.
>

The task in hand is that I have tutorials from a number of different sources
and each author seems to have their own favourite clock frequency, for
example most of the assignments in the PIC in practice use 32.768kHz clock.

To make it easier to try assignments from different tutorials I've decided
to build a multi-frequency clock generator that can be connected to whatever
project board I happen to be using, instead of having to keep swapping
crystals and loading capacitors for the different clock frequencies.

If the clock isn't needed during programming then there's no need to make
provision to connect the clock module to any of the programming header
boards I build.

But the PIC defaults to a certain OSC type !
It doesnt just have none.

"Marra" <cresswellavenue@talktalk.net> wrote in message
news:4dc86828-732e-4502-ab13-00e68a72abe5@s12g2000prg.googlegroups.com...
> But the PIC defaults to a certain OSC type !
> It doesnt just have none.
>

Of course not - one of the ICSP pins is a clock signal, I wanted to know if
that alone is sufficient during programming.

On 2007-12-22, ian field <dai.ode@ntlworld.com> wrote:
> Since the blank PIC doesn't know the type and configuration of its clock
> until its programmed with that info, does that mean that a crystal or EXT CR
> need not be present during programming?

You mean like an AVR does? No. You can program it with no clock at all.

--
Ben Jackson AD7GD
<ben@ben.com>
http://www.ben.com/