On Fri, Aug 09, 2002 at 03:43:03PM -0700, James Newton. Admin 3 wrote:
> source= http://www.piclist.com/postbot.asp?id=piclist\2002\08\09\013248a
>
> ANTI-PROGRAMMER:
> I can see where Byron is coming from... rather than making a beginners life
> easier by teaching him how to program a chip faster or offering YET ANOTHER
> alternative to programming a chip, just skip the programming issues entirely
> and move on to getting something interesting, instructive and possibly
> useful into and running on a PIC with some IO junk ready to go.
>
> Later, if you want to add a ZIF socket on a Daughter Board (or a SMT socket
> for that matter) and download a programmer application into the main PIC,
> great.
>
> Or maybe you want to add a stepper controller board and hook the thing up to
> a physical device that needs to be moved about.
>
> Or... whatever... the point is: Make getting working code into the PIC a
> NON-ISSUE. Concentrate on teaching people how to do things with code in the
> PIC and some simple hardware.

Thanks James,

I'm glad that someone sees exactly what I'm talking about.

>
>
> INTERFACE:
> The interface to the host is always going to be a pain. As pointed out by
> many, every path leads to failure in some subset of the possible cases. I
> think there is only one solution: Redundancy.
>
> - Parallel: Start with a standard parallel port interface via an 8 bit port
> on the PIC and 3 control lines from another port

I know where you're coming from here. The only thing that I find bothersome
is that parallel interfaces take up so much I/O real estate. You're literally
talking about the entire PSP on a PIC for the interface! I'd almost rather
give up a body part than 11 I/O lines.

> [ Then have a USB parallel adapter. Edited for brevity.]

>
> - Serial: Include a minimal TTL-RS232 adapter (resistors and zenor diode)
> http://www.piclist.com/io/serial/ttl-rs232.htm
> (see Peter L. Perez's comments near the bottom)
> and include a header for Ashley's RCL-1 TTL to RS232 adapter
> http://www.piclist.com/io/serial/RCL1.htm
> so that if you can't get a good serial connection with out the max232 on
> board, it will be easy to add.

I never realized that MAX232s had problems with some serial ports. Can you
point me to an example?


>
> EXPANSION:
> - DON'T GET HUNG UP ON ADDING EVERYTHING RIGHT NOW
> - Make the system modular with a good connector (header) that will allow you
> to add (even daisy chain) other devices later

Ok Course. I put on the table a long time ago that a complete I/O port should
be available and that each and every one of the onboard peripherals should
be jumpered so that they can be disabled. If that takes a 3 state buffer chip
where the jumper disables OE (like 74HCT541s or 74HCT245s or their equivalents)
that would be fine.
>
> Hey... that sounds sort of like... CUMP

Except that the CUMP is designed to be a programmer (and a universal one at
that) instead of being the primary design target. But many of the same
principles apply.

BAJ

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