PIC to ISA bus interfacing weird problem

[kalyan]

Hi all,

I am interfacing pic microcontroller (pic18f452) to
FDC37c672 from SMSC. FDC37c672 has some UART and IrDA
capabilities which I want to explot.

It has an ISA bus interface. I am able to read the
registers from the FDC37C672.
But for some reason I am unable to write to the
FDC37C672 using PIC using C. So, I connected it to
Computer's ISA slot and wrote code Visual C++. On PC,
I am able to read and write to FDC37C672. I am not
sure what is wrong with my circuit. Did anyone ever
face any problem like this. I want to learn from your
experience.
Please feel free to suggest me. I can send you
schematics of my PCB board if you are interested in.

Thanks,
Kalyan

 

[Paul Burke]

kalyan wrote:

But for some reason I am unable to write to the
FDC37C672 using PIC using C.

Are you decoding the address properly? I don't know anything about your
device, but you have to make sure your IORD or MEMRD lines are asserted
and also the AEN is in the appropriate state. Get out the scope and
look! Should be a lot easier with your PIC interface than on an ISA bus
where there's all sorts of other traffic to worry about.

Paul Burke