Motorola GP series Manuale d'uso - Pagina 5

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1.0

Keypad and Flexible Connectors

1.1

The keypad block diagram is shown in Figure 1-1. 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 then sample the analog to digital voltages

at the keypad row and keypad column and map it with a table so that the key pressed being can be

identified. Once the key has been identified, the message that corresponds to the key will show up

at the display.

The LED_EN setting is set by the codeplug. When the value is set to high, the LED does not light up

during power up and vice versa.

1.2

Flexible ribbon circuits (flexes) are used to connect the keypad and radio front panel components

with the circuit boards. The flexes are locked into place in their connectors by latches which must be

released before the flexes may be disconnected during maintenence disassembly.

Two types of flexible ribbon circuits are used in the radios:

■

Keypad/Controller Interconnect flex - used for connecting the keypad with the main board

circuits.

■

Universal Flex connector - used to make connections to the Speaker, Microphone and

accessory connector.

Data

40 pin connector

Key_Int

Comparator

LED

Figure 1-1 Keypad Block Diagram

THEORY OF OPERATION

Keypad Column

Keypad

Row

Keypad

Button

Chapter 1