Hi Dennis,

At great personal risk (after the way I screwed up the last time), I would
ask if you'd looked at the voltage at the Pin?  I suspect the PIC is
overpowering the pull down and the actual voltage of the pin is still above
the 0/1 threshold.

The other thing I would be concerned about is you have designed in bus
contention.  Why don't you use RA4, which is an Open-Collector Output, pull
the line hi and if you have multiple devices (ie other devices than the PIC)
use open-collector outputs on them as well.

Good Luck

Myke
>Hi.
>
>First of all, I want to thank everyone for the help with the
>54/84 I/O pins.
>
>I'm now having problems with the following.
>I have set an output high.
>I *know* that the external system will pull it low at a particular
>moment and I want to know when this happens.
>So, I'm simply monitoring the output pin with the following.
>
>CHECK_RB4
>   BTFSC   PORT_B, RB4
>   GOTO    CHECK_RB4
>   ---               ; at this point the external system has
>                     ; pulled it low.
>
>After reading the replies to my previous question I thought that
>this should work. But it doesn't.
>What am I doing wrong here? (I'm using a 16LC84 RC, 4 Mhz)
>
>Dennis.
>******************************************************************************
>*             -=[ Dennis Velthuis =-    -= denv@htsa.hva.nl ]=-              *
>*                 -=[ Raving His Way Into Tha Future :-) ]=-                 *
>*                  -=[ http://htsa.htsa.hva.nl/~denv ]=-                     *
>*     -=[ U Have The Right to Exchange Information, So Use This Right! ]=-   *
>****************************************************************************
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>
>

Do you ever feel like an XT Clone caught in the Pentium Pro Zone?