It's been years since I've used the 8255 but I think you have to be caref=
ul
with its reset line.
Study the data sheet for proper timing sequence too.
Rick

dtth wrote:

> I=92m using PIC 16f877 to make a multipurpose I/O card with 34 I/O, 2
> analog inputs, 2 analog outputs and an RS232 port.  8255 is used to
> expand my I/O. I=92ve tried sending configuration word to 8255 and the
> data is ready at the data pins, yet there=92s no response from the I/O
> ports of 8255. What=92s wrong? Has anybody interface PIC with 8255 befo=
re?
> Where can I find sample code from the web?
>
> Thanks for your attention.
>
>
>
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