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RE: GPIO LPT1 and LPT2 Acting Differently



Hi,

LPT1 has a buffer (74245) between ETRAX and the pins. In your case the
buffer 
interprets the unconnected signal as 0 but ETRAX gets it as 1. The
solution
is to never leave an input unconnected. Connect it to GND or +5V through
a 
resistor.

/Mikael

-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com">mailto:owner-dev-etrax@xxxxxxx.com] On
Behalf Of Dave Matlock
Sent: Friday, December 05, 2003 7:09 PM
To: dev-etrax
Subject: GPIO LPT1 and LPT2 Acting Differently


I'm running the latest devboard release on the 82 server and I'm using
the GPIOG driver to access the data pins on both parallel ports.  The
ports are acting differently, and I'm not sure why.  

When I use LPT1 I can read the inputs and it works great - when I apply
+5V to any of the 8 data pins, the pin reads high and when I remove the
+5V the pins reads low.  However, when I use LPT2 it works differently.
+5V makes the pins read high, but removing the +5V does not clear the
pin state; I have to apply GND to the pin to clear it.  It does not
matter which way it works, but I would like them to work consistantly.
What do I do?