Hello Morgan,

We generally design in a two pin interface to our Pic projects -- it's
called RS-232 full duplex send / receive. The interface is active in a
real-time mode in the full production versions if possible. I guess if you
wanted just send or just receive it would qualify as one pin. After having
invented lots of standards for wired and wireless serial protocols we have
decided to use standards whenever possible. RS-485 works great too, but is
a little more load on the processor.


Tom

Have anyone designed a one pin interface?

It would be nice to have a simple monitor suopport program in every PIC, so
if we want to check inside it when it is working (or working wrong) we can
attach a specialised unit with a display and keyboard to it. We must use
minimum number of pins for it (one), and it should be possible to implement
"everywhere".

The monitor unit I believe can be built using a F84, LCD and a few keys to
select adress and view and change registers, force gotos or calls to
stop,test,run routines etc in the target system.

The target system?s routine shoud of course be as possible as possible, and
perform som kind of erroer check so it don?t treat noise as instructions.

The monitor scans the keys, decode it to simple instructions and send them
to the target. The target sends back register contents binary, which the
monitor decodes and displays.