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Motorola CM140 Informações sobre o serviço

2-4

3.0

Controlhead Model for CM160 and CM360

The controlhead contains the internal speaker, the on/off/volume knob, the microphone connector,

several buttons to operate the radio, three indicator Light Emitting Diodes (LED) to inform the user

about the radio status, and an 8 character Liquid Crystal Display (LCD) for alpha - numerical

information e.g. channel number or call address name.

LED

Backlight

Control

Keypad

Resistors

Keypads

3.1

Power Supplies

The power supply to the control head is taken from the host radio's 9.3V via connector J103-9, The

9.3V is used for the LEDs and back light, the 5V is used for the LCD driver (U3) and level shifter

(U4). The stabilized 3V is used for the other parts.

3.2

SPI Interface

The host radio (master) communicates with the control head through its SPI bus. Three lines are

connected to the shift register (U8):SPI clock (J103-17), SPI MOSI (J103-16), shift register chip

select (J103-15) and LCD driver chip select (J103-18).

When the host radio needs to send date to the shift register, the radio asserts the shift register chip

select and the data is loaded to the shift register. For example, the host radio sends data to change

display channel or change LED status.

9.3V

LED

Indicators

Control line

Boot_Res / SCI

Mux.

Control

DTMF

Row/Column

LCD

Level

Driver

Shifter

9.3V

Shift

PTT

circuit

Boot_Res (DTMF-

Column)/ SCI

(DTMF-Row)

THEORY OF OPERATION

8 pin JACK

connector

2-pin speaker

connector