Chapter 3 Keypad; Controller Board; Figure 3-1. Keypad Block Diagram - Motorola HT Series Service Manual

Chapter 3 Keypad

The keypad block diagram is shown in
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.
Display
3.1

Controller Board

The controller board is the central interface between the various radio functions. It is separated into
MCU digital and audio/signalling functions as shown in
Figure
Data
18 Pin
Connector
LED

Figure 3-1. Keypad Block Diagram

3-1. The comparator compares the voltage when any
40 Pin Connector
Key_Int
Comparator
Figure 3-2.
Keypad Column
Keypad
Row
Keypad
Button
3-1