D0-D13, and A0-A5 (D14-D19). I guess that does make 20.
keypad down to 1 pin - there have been plenty of discussions on that too, using an analog input and a bunch of resistors.
Folks have shown successful examples.
D0-D13, and A0-A5 (D14-D19). I guess that does make 20.
keypad down to 1 pin - there have been plenty of discussions on that too, using an analog input and a bunch of resistors.
Folks have shown successful examples.