74922 Encoder

MR

I have a 3x4 matrix keypad that is 3 columns and 4 rows.

I am using the 74c922 keypad encoder with this keypad from Jameco

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=190562

I can't get the thing to work right.

What should I do about Column 4 if all I have is 3 columns and four rows?

Mike Green

There's a Nuts and Volts column (#97) on the use of the 74C922. Have a look at that.

If you don't use column 4, leave it unconnected. That will act just as if it existed, but was never pressed.