Controlhead Model For Cm160 And Cm360; Power Supplies; Spi Interface - Motorola CM Series Service Information

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 LED
Backlight Backlight
Backlight Backlight
Control Control
Keypad Keypad
Resistors Resistors
Keypads 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 9.3V
LED LED
Indicators Indicators
Control line Control line
Boot_Res / SCI Boot_Res / SCI
Mux. Mux.
Control Control
DTMF DTMF
Row/Column Row/Column
Row/Column Row/Column
LCD LCD
LCD LCD Level Level
Driver Driver Shifter Shifter
9.3V 9.3V
Shift Shift
Register Register
PTT PTT
circuit circuit
Boot_Res (DTMF- Boot_Res (DTMF-
Column)/ SCI Column)/ SCI
(DTMF-Row) (DTMF-Row)
THEORY OF OPERATION
8 pin JACK 8 pin JACK
connector connector
2-pin speaker 2-pin speaker
connector connector