Just wanted to run this past the wisdom of the list.

Port Pins RA4 - RA7 on a 16F887 are successfully driving a standard 2 x 16
LCD (via a shift
register).

Want to add 4 push buttons (ENTER, EXIT, UP,DOWN).

Possible solution

use weak pull downs approx 4.7K from port pin to ground.

use 680ohm from port pin to N/O push button then  to +V.

PIC should still be able to drive pins high or low as needed to control LCD
even when switch is pressed.  Quick test seems to indicate this is ok.

Current when PIN driven low and switch is pressed, I =3D V/R =3D 5/680 ~ 7 =
mA
(+ LCD and shift reg loading)

Is this plausible.

Cheers Justin
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.