Keypad; Figure 8-4. Keypad Block Diagram - Motorola P100 Series Detailed Service Manual

8-6
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.
KEYPAD
Left Right
P1 P2 P3
NUMBERS
Key
detect
Key row
Key
column

Figure 8-4. Keypad Block Diagram

136 – 174 MHz VHF Theory of Operation: Keypad
MCP