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4 - 4
4-4 DSC CIRCUITS (DSC UNIT)
4-4-1 DATA INTERFACE CIRCUIT
The control signals from DS-100 CLASS D/DSC TERMINAL
are shaped waveform at the SCHMITT circuit (IC3) via the
photo-coupler (IC2), and are then applied to the MAIN unit
via J2 (pin 11).
4-4-2 DSC MODULATION CIRCUT
The modulation signals from DS-100 are converted into a
600
Ω
impedance at T1 and passed through the high-pass
filter (IC1a) with +6 dB/octave characteristics.
The signals from the high-pass filter (IC1a) are passed
through the splatter filter (IC1b) to suppress unwanted 3 kHz
or higher signals. The filtered signals are then applied to the
TX modulation circuit via the buffer amplifier (Q30) and ana-
log switch (IC12, pins 1, 2) on the MAIN unit as a DSC mod-
ulation signal.
4-5 POWER SUPPLY CIRCUITS
4-5-1 VOLTAGE LINE (MAIN UNIT)
4-6 LOGIC CIRCUITS
4-6-1 MAIN UNIT
• MPU
IC16 is a 16 bit multifunction micro-computer and contains
FLASH memory, serial I/O, timer, A/D converter, D/A con-
verter, programmable I/O, ROM and RAM.
• SYSTEM CLOCK CIRCUIT
X3, X4 are crystal oscillators and oscillate 7.9872 MHz and
32.768 kHz system clocks for the MPU (IC16) respectively.
• RESET CIRCUIT
IC15 is a reset IC. When turn power ON, IC15 outputs a
reset signal (“LOW” pulse) to MPU (IC16, pin 75).
• LOW BATTERY DETECTOR
VCC voltage is divided by R204, R205 and is applied to the
low battery detector section in the MPU (IC16, pin 42).
4-6-2 LOGIC UNIT
• CPU
IC1 is an 8 bit single chip micro-computer and contains LCD
driver, serial I/O, timer, A/D converter, programmable I/O,
ROM and RAM.
• SYSTEM CLOCK CIRCUIT
X1 is a ceramic oscillator and oscillates a 4.91 MHz system
clock for the CPU (IC1).
• LCD DRIVER
IC2 is a LCD driver for a dot matrix LCD.
• DIMMER CIRCUIT
CPU (IC1) and Q2, Q3, Q8 are dimmer circuit and control
the LCD backlight (LED).
• CONTRAST CIRCUIT
CPU (IC1) and Q1, Q4 are contrast circuit and control the 8
step display contrast.
4-7 PORT ALLOCATIONS
4-7-1 SUB CPU (LOGIC unit; IC1)
LINE
HV
HVS
VCC
8V
A5V
D5V
T8
R8
DESCRIPTION
The voltage from the connected DC power sup-
ply.
Same voltage as the HV line which is passed
through the [PWR] switch (LOGIC unit; S1).
Same voltage as the HVS line which is passed
through the power controller (RL1).
Common 8 V converted from the VCC line at the
8V regulator circuit (IC8).
Common 5 V converted from the 8V line at the
analog 5V regulator circuit (IC9).
Common 5 V converted from the 8V line at the
digital 5V regulator circuit (IC7).
Transmit 8 V controlled by the T8 control circuit
(Q20, Q21) using the SEND signal from CPU.
Receive 8 V controlled by the R8 control circuit
(Q22, Q23) using the RCV signal from CPU. The
controlled voltage is applied to the receiver cir-
cuits.
27,
28, 29, 30
31–38
42
43
44
46
47
51, 52
54
55
58–60
61
62
63
64
75–77
78–80
LRESET,
E, RW, RS
DB7–
DB0
SCAN
CHWX
CH16
SQLV
KEYM
DIALA,
DIALB
SRXD
STXD
CONTSEG3–
CONTSEG1
DTRS
IC
DSC
HL
DIM3–
DIM1
CONDOT3–
CONDOT1
Output ports for the LCD driver (IC2)
control signals.
I/O port for the LCD driver (IC2) control
signals.
Input port for the [SCAN] key.
Input port for the [DIAL] key.
Input port for the [CALL] key.
Input port for the squelch volume level.
Input port from the microphone (HM-
126) for remote control signal
Input ports for the [CHANNEL].
Outputs communication data for main
CPU (MAIN unit; IC16).
Input port for the communication data
from main CPU (MIAN unit; IC16).
Output port for the LCD contrast.
Input port for the [16] key.
Input port for the [DIMMER] key.
Input port for the [DUAL] key.
Input port for the [HI/LO] key.
Output LCD backlight control signal for
the dimmer circuit (Q2, Q3, Q8).
Output port for the LCD contrast.
Pin
Port
Description
number
name