- on Test & Measurement
- Published in issue 3/2005 on page 0
Delphi for Electronic Engineers (3)
Part 3: an external calculator
In the previous article we saw how we could implement a simple calculator using
The external keypad, which we'll build ourselves, consists of 16 keys in a configuration of 4 rows by 4 columns. When a key is pressed, a single row is connected to a single column. The combination of the exact row and column is unique for each key.
By activating each column in turn and then checking which row has a signal, we can determine which key has been pressed.