3·3 Logic Circuits - Icom IC-R7100 Service Manual

3·3 LOGIC CIRCUITS 3·3·4 BAND SELECTION DATA (LOGIC UNI
The LOGIC circuit consists ol a one chip a-bit CPU (ICS),
an 1/0 expander (1C4) controlling the input level l rom
tne
key matrix, a 84 k-bit CMOS RAM (ICll) and a CI·Y c ircuit.
The 64 k·bi\ CM05 RAM (ICll) contains 900 memory
channels which can ba divided into 9 banks and 20 inde-
pendent. program channels. The CI·V circuit controts
frequency, mode, memory channels etc..
by
connecling
the rec eiver with an optional CT·17 CI·Y LEVEL CON·
YERTER to a personal computer equipped w ith an
RS·232C port.
3·3·1 RESET CIRCU IT (LOGIC UNIT)
The reset circuit resets the CPU (ICS), the LCD drivers
(1C8, IC9) and the 1/0 expander (1C4) when the three-
term inal voltage regulat o r (IC13) detects S V and outpu ts
S Y. The leading edge vo ltage is applied to a time con-
stant (R24, C22). The " LOW"
pulse-type
signal is
output
trom
the time constant during Ihe delay time .
The signal Is inverted at 06 and is Ihen applied to a
Schmitl t rigger c ircuit (IC7) to tu ne the pulse-type signaI.
The rese t signal is applied to the reset ports ol the CPU
(ICS), the LCD dr ivers (ICa, IC9) and the 1/0 expand er
(1C4). 0 14 discharges the voltage of C22 .
3·3·2 DIMMER CIRCUIT (LOGIC UNIT)
The band control
signaIs
are changed depending on .
receive trequencies. The CPU (ICS) outpu ts the lollow
signals for the RF UNIT, PLL UNIT and MAIN UNIT.
RECEIVE
RF BAN D PLL
FREQUENCY
CONV
Bl B2 B3 84 BH SS VS
25.0000-
H L L L L L H L
89.9999 MHz
90.0000-
L H L L L L H L
249.9999 MHz
250.0000-
L L H L H L L L
511.9999 MHz
512.0000-
L L L H L H H L
761 .9999 MHz
762.0000-
L L L H H H L L
1024.9999 MHz
1025.0000-
H L L L L L H H
1089.9999 MHz
1090.0000-
L H L L L L H H
1249.9999 MHz
1250.0000-
L L H L H L L H
1511.9999 MHz
1512.0000-
L L L H L H H H
1761 .9999 MHz
1762.0000-
L L L H
H
H L
H
1999.9999 MHz
Ths dimmer circuit consists of 02. 03 and 0 16 and drives
backlights (0 54- 0 5 7), ensuring
tnat
brightness does not
change even with a change of power supply. When tne
[DIM MER] swi tch is ON, the CPU (ICS, pin 56) outputs a
" LOW " signal to decrease the base voltage of 03.
• DIMMER CIRCUIT
3·3·3 REGULATOR CIRCUIT (LOGIC UNIT)
IC23 is a S Y th ree-terminal reg ulator. The "LHV" line
is converted trom
me
"HV" line and passes through a
resistor (R29l) on the MAIN UNIT. Then, the voltage
line is applied to IC23. The time constant consists of
R29l on the MAIN UNIT and C7l on the LOGIC UNIT
and protscts Ihe 5 V line
trom
any drastic changes.
3·3·S CPU (I CS) PORT ALLOCATJONS
(LOGIC UNIT)
PORT PORT PIN
DESCRIPTION
NUIoABER NAME NUIoABER
POO- B'l -r-
14- 18 Outputs
the
band control signals
P04
84 , BH for
the
RF UNIT. See the table
shown In the BAND SELECTlON
DATA (3-3-4).
P05 CONV 19 Outputs a band cont rol signal for
the MAIN UNIT. See the tabla
shown in the BAND SELECTlON
DATA (3-3-4).
POS. VS, SS 20,
21
Outputs the band control signals ,
P07
lor
the
PLL UNIT. See the tabla
shown in the BAND SELECTION
DATA (3'3-4).
PlO DIM
56
Becomes ··LOW" when the
(DIMMER] switch is ON.
Pl l SSTB 57 Outputs a strobe signal tor an
optional UT·36 VOICE
SYNTHESIZER UNIT.
P12 PSTB
SB
Outputs a strobe signal lor a PLl
IC (IC1 ) on the PLL UNIT.
P13 EXSTB 59 Outputs a strot>e signal lor a DIA
control IC (IC14) on the PLL UNIT.
P14
REML
61
Outputs an indicator slgnal tor Ihs
(AEMOTE] indicator on the Ironl
panel.
This pon becomes
"HIGH" when the CPU enters 1 he
remale condition via
the
CIN
system.
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