Motorola 68HC12 User Manual page 30

1
4
7
*
Keypad wiring diagram - The keypad is a passive device with only switches that
connect wires on the crosspoint matrix of 4 x 4 wires.
2 3
5 6
8 9
0 #
= push button connection between grid wires
Pins normally pulled high (through pull-up resistors in
6812) - switch closure will temporally pull bit low
Pins normally grounded (held low)
A
B
C
D
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