Logic Circuit; Port Allocations - Icom DS-100 Service Manual

3-6 LOGIC CIRCUITS (LOGIC UNIT)
• CPU
IC1 is 16 bit single chip microcomputer and contains serial
I/O, timer, A/D converter, D/A converter, programmable I/O,
ROM and RAM.
• SYSTEM CLOCK CIRCUIT
X1 is a high-stability crystal oscillator and oscillated a
7.9872 MHz system clock for the CPU (IC1).
• RESET CIRCUIT
IC4 is a reset IC. When turn power ON, IC4 outputs a reset
signal ("LOW" pulse) to CPU (IC1, pin 75).
• LCD DRIVER
IC6–IC8 are LCD driver for a dot matrix LCD.
• INVERTER CIRCUIT
IC4 is a –8V DC-DC converter IC and converts –8 V from the
HV line. The converted voltage (–8V) is used for driving the
LCD.
• CLOCK CIRCUIT
IC3 is a clock IC and also used for backup the position/time
information for DSC.
• DIMMER CIRCUIT
Q2, Q3, Q6 are dimmer circuit and control the LCD backlight
(LED).

3-7 PORT ALLOCATIONS

3-7-1 CPU (LOGIC UNIT)
Pin Port
number name
KEY-3–
1–7 Input port for the [3]–[9] keys.
KEY-9
8 KEY-0 Input port for the [0] key.
10 KEY-L Input port for the [LEFT] key.
11 KEY-U Input port for the [UP] key.
12 KEY-D Input port for the [DOWN] key.
13 KEY-R Input port for the [RIGHT] key.
14 KEY-A Input port for the [A/a] key.
15 KEY-BS Input port for the [BS] key.
Input port for the cloning data from the
19 CLRX
buffer (MAIN unit; D8).
Output port for the cloning data to the
20 CLTX
buffer (MAIN unit; Q9).
Outputs clock signal for EEPROM
23 ECK
(IC2).
Outputs serial data signal for EEP-
24 EDA
ROM (IC2).
Outputs the R8V regulator circuit
26 RCEV (MAIN unit; Q15, Q16) control signal.
High : While receiving
D/A output port for the DSC encode
30 DSMOD signal to the buffer amplifier (MAIN
unit; Q17).
Description
Pin Port
number name
31 CADJ
36 NMEAI
37 NMEAO
38 SQL
DIM0–
41–44
DIM3
45 DDEC
46 UNLK
CS1,
52, 53
CS2
54, RW,
55, 56 DI, E
57 DATAS
58 DATAM
60 BUSY
65 KEY-ENT
66 KEY-CLR
67 KEY-CAL
68 KEY-DTR
69 BEEP
73 CCS
74 PSTB
DB0–
83–90
DB7
96 SCK
97 SO
98 SI
KEY-1,
99, 100
KEY-2
3 - 3
Description
Outputs control signal for the LCD
contrast.
Input port for serial signal from the
NMEA connector (MAIN unit; J1) via
the photo coupler (MAIN unit; IC5)
and buffer amplifer (MAIN unit; IC6).
Outputs serial signal to the NMEA
connector (MAIN unit; J1) via the
buffer amplifier (Q13, Q14, D11).
Input port for noise level signal (DC
voltage) for squelch operation.
Output LCD backlight control signals
for the dimmer circuit (Q2, Q3, Q6).
Input port for the DSC decode signal.
Low : DSC signal is decoded.
Input port for the PLL unlock signal.
Low : While PLL is locked.
Outputs chip select signal for the LCD
drivers (IC6–IC8).
Output control signals for the LCD dri-
ver (IC6–IC8).
Input port for the control signal from
IC-M501EURO via the photo coupler
(MAIN unit; IC8) and buffer amplifier
(MAIN unit; IC6).
Outputs the control signal to IC-
M501EURO via the Buffer amplifier
(MAIN unit; Q11, Q12, D10).
Outputs busy LED (MAIN unit; DS1)
control signal.
Input port for the [ENT] key.
Input port for the [CLR] key.
Input port for the [CALL] key.
Input port for the [DISTRESS] key.
Outputs beep audio signal.
Outputs chip select signal for the clock
IC (IC3).
Outputs strobe signals for the PLL cir-
cuit.
Output data signals for the LCD driver
(IC6–IC8).
Outputs clock signal to the clock IC
(IC3).
Outputs serial signal for the clock IC
(IC3).
Input port for serial signal from the
clock IC (IC3).
Input port for the [1], [2] keys.