Service Manual

MM-E 2072-09333-00
2-38
2-6. CONTROL HEAD MODULE
Figure A-3 shows the schematic circuit diagram of the CONTROL HEAD module for both the
dash-mount and trunk-mount versions.
2-6.1 CONTROL HEAD Module for Dash-Mount Version
Figure 2-18 shows the functional block diagram of the CONTROL HEAD module used in the
Micom-Z dash-mount version.
2-6.1.1 Microcontroller
Refer to Figure A-3.B.
a. Microcontroller. The microcontroller, U1, is a 16-bit microcontroller with a 8 kB data RAM, a
128 kB flash memory that stores the application program, two A/D converters with 8
multiplexed inputs, two D/A converters, two UARTs and a large number of input and output
ports. Its internal clock oscillator uses the 7.3728 MHz crystal Y1 as a frequency reference.
b. Keypad Interface. The keypad (Figure A-3.C) is a 5×5 matrix of switches, with the row lines
connected to the 3V3_IF line via series resistors. The row and the column lines are connected to
ten of the I/O ports of U1, which can thus detect the pressing of each key, including the volume
control keys.
LCD
P6
J3
Microcontroller
U1
P2
P4
Panel
Keypad Lighting
Control
Q504, Q506
LCD Heater
Control
U7, Q1, Q3, Q501
LED Lighting
Control
Q502, Q503
DC/DC
Converter
U6, Q2
13V8DC
14V7
Y1
3V
Regulator
U5
To
LORD
3.3V
Regulator
U4
3V3
P3
Serial Control Channel
(UART 0)
3V0
Audio
Connector
5V0
Figure 2-18. CONTROL HEAD Module for Dash-Mount Version, Functional Block Diagram