I might be, too, once I have enough experience with
it. If I can't
make a full desktop host speak HP-IB through glue logic (well, possibly
aside from timing constraint reasons), I'm not going to be able to make
a microcontroller do it.
True. You could, of course, use one of the HPIB interface chisp, but most
ahve been discontinued. They are still easy to find, but I wouldn't want
to design a device round them.
From what I remember, there is only one timing-tricial
bit of the HPIB
interfce. I think it's sasserting the approprate data lien on a
parallel
poll -- there is no hanschake ivolved, so the device has to repsod
quickly enougjh. Everything else is a fully interlocked handshake. A
microcontrolelr _should_ be able ot keep up wit hthe timing requirements,
even for parallel poll, but 'should' is a prime source of hard-to-find
headaches :-). If I was doing it, I'd add the minimal external logic and
do it in hardware...
I half-thought about using an R-pi. Banging the
HPIB handshake on the
pins of htat user port connecotr (with buffres added, of course).
the R-pi has just about everything else you need, includign a USB
host interface.
A USB host interface is only marginally more useful to me than it is to
you. Serial line or Ethernet - preferbaly serial line *and* Ethernet -
No, I didn;t mean using a USB interfce to communicate with some other
host computer. I meant that the R-pi can be a USB host, and thus you can
conenct USB storage drevices, like memory sticks, to it.
My idea for this devie is a ttoally stand-alone thing that connects to
the HPIB. It takes some kind of standard flash memroy to simulate the
disk storage (USB sticks, SD cards, whatever). Thrre si some way of
selecting a particular disk image on said flash memroy (keypad/LCB,
RS232 port to a terminal, etc). It doens't need a PC to run.
is what I'd want. And I wouldn't spend money
on a pi in any case, not
when I've got plenty of perfectly good hardware lying around.
The problem for me is that HP machines re not always small, so there's
not enough room to put the one I am working on _and a PC setup_ on my
bench at the same time. Hence my idea for a small stand-alone thing. It
shouldn't; be hard to do.
-tony