Motorola GP328 Detailed Service Manual

5-1
Section 5
KEYPAD BOARD INFORMATION
1.0 Theory of Operation
Keypad
The LED_EN setting is set by the codeplug. When the value is set to high, the LED will not light up
during power up and vice versa.
U602 is a comparator that will compare the voltage when any one of the keypad row or keypad
column keys is being pressed. Therefore when a key is being pressed, it will send a message to the
microprocessor through the output (KEY_INT) telling it that a key has been pressed. The
microprocessor will then sample the Analog to Digital voltages at the keypad row and keypad column
and map it with the table so that the key being pressed can be identified. Once the key has been
identified, the message that corresponds to the key will show up at the display.
Figure 5-1: Keypad Block Diagram
40 pin connector
Comparator
Keypad
Button
LED
Display
18 pin connector
Key_Int
Keypad Column
Keypad
Data
Row

Motorola GP328 Specifications

General

Channel Capacity	16 channels
Operating Temperature	-30°C to +60°C
Sealing	IP54
Frequency Range	136-174 MHz (VHF), 403-470 MHz (UHF)
Power Output	1-5W (VHF), 1-4W (UHF)
Dimensions	137 x 57.5 x 37.5 mm
Power Supply	7.5V
Battery Life	8 hours (High Power), 11 hours (Low Power) with standard NiMH battery
Weight	420g (with standard battery)