On Sat, Jan 01, 2011 at 05:22:22PM -0500, Michael Watterson wrote:
> On 01/01/2011 18:50, Byron Jeff wrote:
> > With the death of parallel ports, and to a large extent serial ports on=
 PCs,
> > there's no out of the box interface that can be driven in software on a=
 PC.
> yes there is. It's USB,
>=20
> It's trivial to write program for PIC in JAL to use existing USB HID,=20
> Storage or Serial Drivers.

But therein lies the catch 22 that I refered to. To program a PIC in JAL
you need a programmer of some sort. PIC, unlike some other chips in the
past, do not have a built in bootloader, so that they can be programmed out
of the tube with a serial interface.

The legacy ports always gave you pins that you could wiggle in software.
USB does not without attaching something else to it. The cheapest and most
ubiquitous device nowadays for that is a USB serial interface.

>=20
> As long as you are doing data and not "bit-banging" any language/program=
=20
> can use a virtual serial port provided by a USB interface.
>=20
> Then the PIC can use I2C,  Serial, Parallel, PATA, ICSP and many other=20
> interfaces. An 18F2550 or 18F4550 is a good one to start playing with.

But how do you program it? I know the typical answer to this is "buy a
programmer". But if you're only going to use it once in a blue moon,
because the primary mode of development is a bootloader, it's not as simple
a decision as you may think.

>=20
> In fact the Pickit 2 is this using USB HID. You can use it as a logic=20
> analyser, TTL serial adaptor or ICSP. You can even put your own firmware=
=20
> on it. Quite inexpensive.

Exactly my point. You need a programmer in order to program the chip.

I know I've been gone awhile, but I was pretty sure everyone here knew my
thoughts on the development process. There are tons of threads going back
several years on this particular discussion.

Modern PICs can program themselves. No additional programmer required. But
it requires software to get into the part so that it can program itself.

Catch-22.

My Trivial LVP here:

http://www.finitesite.com/d3jsys=20

always served that purpose for me, and quite a few other hobbyist. But the
death of parallel ports (or at least integrated ones) killed this design.
I'm searching for a replacement.

BAJ
--=20
Byron A. Jeff
Department Chair: IT/CS/CNET
College of Information and Mathematical Sciences
Clayton State University
http://cims.clayton.edu/bjeff
--=20
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