Service manual

2-2
R = Regulator Jumper
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,
then makes a comparison with a map table to identify the key pressed. Once the key is identified, a
corresponding message is displayed.
The LED_EN is set by the codeplug. When the value is set to low, the LED lights up during power up.
A high codeplug setting disables this feature.
Figure 2-2: Keypad Block Diagram
Table 2-1 VDD Regulator Scheme by Band
Band
Vdd
Regulator
Scheme
Low Band Dual
VHF Dual
UHF Dual
800 MHz Dual
900 MHz Dual
Table 2-2 Radio Jumpers
Jumpers
Dual Vdd
Regulator
Scheme
Single Vdd
Regulator
Scheme
R401 Y Y
R402 N N
R403 N Y
R404 N N
R405 Y N
40 Pin Connector
Comparator
Keypad
Button
LED
Display
18 Pin
Connector
Key_Int
Keypad Column
Keypad
Row
Data