Wagner Lipnharski suggested:

>Just to use the opportunity:
>An easy way to have a key and a indicator led connected to a single
>microcontroller port pin is connect the LED (anode) with a resistor (330
>Ohms) to +VCC (+5Vdc) and the catode to the port pin, the key goes to
>the same port pin to ground via another resistor (100 Ohms).

<big snip>

This has a potentially fatal flaw - the LED resistor and the switch resistor
form a voltage divider which means that the 'switch pressed' voltage at the
pin drops to about 1 Vdc instead of 0 Vdc.

The soloution is simple - put both resistors in series, with the mid point
of the resistors going to the switch.

dwayne


Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax

Celebrating 15 years of Engineering Innovation (1984 - 1999)

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Do NOT send unsolicited commercial email to this email address.
My posting messages to Usenet neither grants consent to receive
unsolicited commercial email nor is intended to solicit commercial
email.