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   Re: User port
   Author:   John Iannetta <73510.2152@CompuServe.COM>
   Date:   1999/02/20
   Forum:   comp.sys.cbm
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   _________________________________________________________________
   
    Martin Gunnarsson said,

'As default all the 8 pins (pb0-pb7) is set as inputs. That way there's 5V
between every pin and the ground. It would be pretty bad if all the relays
(one for each pin) would be open before the program loads. Actually it could
cause pretty much troble.
So now I was wondering if there's some kind of "flag pin" or some other way
I can find out if a pin is set to input or output. Otherwise I'll just have
to use a manual switch and turn on the realy card after the program is
loaded.'.

    There is no such pin, but I suggest thst you do the following.  Use PA2
(pin M, bit 2 of $DD00) to deenergize  all relays when that pin is high.  On
power-up, both PA and PB are set to all inputs, so that pin is high (behind
about 5 kohms of resistance).  Then, a KERNAL routine defines PA2 as an output,
and sets the bit (so it is still high, but it can source more current).  In
your program, clear that bit:

poke56576,peek(56576)and251

That should take the line low and let the relays work.

--
I pressed RETURN, and the message said, "Missing GOSUB".

                          John
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