Gregg Kricorissian wrote:
>
> Dear PIC'ers
>
> As usual I have this problem ... I haven't seen anything written about
> serial in-circuit programming of the 16LC84, aside from the little bit in
> the data book on page 52.  I hadn't paid much attention to it until
> recently; that is, now that I know I have to use an SOIC package device in
> the final product design.
>
> I see in-circuit programming to be very advantageous, since it will allow us
> to load a routine for hardware verification during manufacturing test, and
> then re-program the 16LC84 with the operating code ... all without
> disturbing the hardware.
>
> Trouble is I can't find anything in my MPLAB or Picstart PLus manuals (or
> the Microchip CD) about considerations for in-circuit programming: neither
> how one should size the isolating resistors shown on page 52, nor the
> availablilty of a commercial serial programmer.  Is it one of those things
> that's "left as an exercise for the reader", or is there a product already
> available to do the job?
>
> Because of time constraints, I'd rather buy than build one, but building is
> still do-able.  Perhaps it's nothing more than building a driver/buffer
> stage between my Picstart and the application circuit?  Does anyone out
> there have any good pointers for in-cicuit programming?
>
> Many thanks,
> ... Gregg

Take a look at
   http://www.ebar.dtu.dk/~c888600/newpic.htm
or
   http://www.gbar.dtu.dk/~c888600/newpic.htm

Programmer is not production quality. But it meets RS232 levels.
Programming voltage is 13V and Vcc is 5.1V during program/read.

Regards,
Jens Dyekjfr Madsen