2
RC-2000
CIRCUIT DESCRIPTION
Panel Section (LCD ASSY : B38-0829-05)
The panel section controls serial communications with
the main unit control section, the key input circuit, the dis-
play circuit, and the dimmer circuit through the microproces-
sor (IC4).
s Serial communications circuit
A buffer amp is inserted in order to protect the micropro-
cessor ports.
s Key, Volume input circuit
Circuits to operate the panel section keys are connected
to each microprocessor port. The PSW key is pulled up and
the other keys are pulled up with software within the micro-
processor. Rotary encoder operating circuits are connected
directly to the microprocessor. The control divides the
power supply voltage, reads the A/D port of the micropro-
cessor, and transfers that data to the main unit.
s Display circuit
Display section is a 188 x 54-dot full-dot matrix LCD con-
trolled by two LCD. As shown is Figure 1, the master IC
(IC2) side is connected to 22 common dots and 88 segment
dots and the slave IC (IC1) side is connected to 33 common
dots and 100 segment dots. The LCD drive voltage is ob-
tained by raising the power supply voltage (5V) within the IC.
s Dimmer circuit
The dimmer circuit switches the lamp brightness to one
of four levels or OFF (See table1). The current flowing to the
LEDs is varied by selecting resistors from R8 to R14.
Dimmer level
DIM 0
DIM 1
DIM 2
DIM 3
1H
L
L
L
2L
H
L
L
3L
L
H
L
4
LLL
H
OFF
L
L
L
L
Table 1
Port logic
LCD
188
× 54 (dot)
Microprocessor
IC4
33
COM
22
COM
88
SEG
100
SEG
LCD
Driver
IC2
LCD
Driver
IC1
X54-329
9V
D30
R42
D24
D25
R39
D26
D27
R40
D28
D29
R41
IC4
Microprocessor
DIM3
Q8
DIM2
Q7
DIM1
DIM0
Q6
Q5
Q3
R8
R10
R9
R12
R11
R14
R13
LCD ASSY
Q2
Q4
Fig. 1
Display circuit
Fig. 2
Dimmer circuit
