Motorola CP Series, Service Manual, Page: 78 / 154

8-6 136 – 174 MHz VHF Theory Of Operation: Keypad
8.5 Keypad
Left, Right and P1 to P3 keys are directly connected to microprocessor via 22 pin connector. When
any of these keys is pressed, the voltage goes "low" and microprocessor detects it.
For full keypad models, the number keys are in matrix type which consisted of 3 rows and 4 columns.
When any of these keys is pressed, the voltage goes "low" and microprocessor interprets the voltage
for each key press.
Figure 8-4. Keypad Block Diagram
KEY P AD
L e f t
N UMB ER S
R ig h t
P1 P2 P 3
K ey
K ey ro w
K ey
co lu mn
22pin
connector
K
eypa
d
boar
d
22pin
connector
Main
boar
d
MCP
d etect