Keypad
2-3
2.3
Keypad
The keypad block diagram is shown in Figure 2-2. The comparator compares the voltage when any
one of the keypad row or keypad column keys is pressed. Pressing a key sends a message to the
microprocessor through the output (KEY_INT) line signifying that a key has been pressed. The
microprocessor then samples the Analog to Digital voltages at the keypad row and keypad column,
and makes a comparison with a map table to identify the key pressed.
Figure 2-2. Keypad Block Diagram
40 pin connector
Comparator
Keypad
Button
9 pin connector
Key_Int
Keypad Column
Keypad
Data
Row