Hi list,

Some weeks ago I wrote a desperate plea to the PIClist asking if anyone
had any experience with implementing GPIB on a PIC-based system, using a
suitable controller IC (such as a modern day equivalent of the uPD7210).


Basically I had got myself into deep water. I pleaded with my company to
let me take charge of developing an instrumentation product in-house,
rather than their original idea of contracting out the design, because I
felt that it would be an extremely difficult challenge which I *could*
do if I tried hard enough, and would be very rewarding for me to do.
They gave in and let me do it, with some degree of reluctance: I'm a new
guy there with not a lot of experience, and these things will each sell
for the price of a house...

It got off to a really good start. In a relatively short time I managed
to learn C and get to grips with C18, having only been experienced with
assembler beforehand. I soon had the barebone instrument completed,
together with working drivers for a QVGA LCD using an EPSON S1D13305
controller. However, I never really bargained for how challenging it
would be to implement the GPIB interface. When I started to learn about
it, I almost completely lost it with worry over what I had got myself
into..

Anyway, I eventually got hold of some INES IGPIB 72010 chips and after
some struggle, I got my 18F452 talking to it properly. I spent days
going through the INES-supplied C drivers and converting them to work on
my PIC platform.

I hooked up a PC with a GPIB card and tried to send a text string. I
couldn't believe it when my text string displayed on my LCD. It worked
first time, together with correct handshaking, EOI operation and so on.
And I got text sending back properly, too. There's a bit to do yet, like
making sure my system meets all of the 488.2 requirements and so on, and
then lots of testing at a customer's lab (that should be, erm, daunting)
but otherwise, I consider the greatest hurdle in my project to have been
surmounted.

By the way, I solved the problem of my 72010 apparently being 'dead' by
switching to a different oscillator frequency. It's supposed to work in
both 8MHz and 30MHz modes, but I could not get it to do anything on a
30MHz clock, no matter what I did. Switched to 8 and bingo..

So I'd just like to thank those who kindly offered me advice in response
to my GPIB posts previously.

Cheers

Trev

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