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CIRCUIT DESCRIPTION
Panel Section (LCD ASSY:
B38-0772-15)
The panel section controls serial communications
with
the main
unit control
section,
the key input circuit, the
display
circuit,
and
the
dimmer
circuit
through
the
microprocessor (iC4).
@Serial communications circuit
A buffer is inserted in order to protect the microproces-
sor ports.
@Key input circuit
There is one microprocessor port for each panel section
key. The PSW key is pulled down and the other keys are
pulled up with software within the microprocessor.
The
rotary encoder is input directly to the microprocessor.
@Display circuit
The TM-V7AVE display section is a 152x45-dot full-dot
matrix LCD controlled by two LCD.
As shown in Figure 16,
the master IC (IC5) side is connected to 32 common dots
and 80 segment dots and the slave IC (IC6) side is
connected to 13 common dots and 72 segment dots.
The
LCD drive voltage is obtained by raising the power supply
voltage
(5V) within
the
IC.
Also,
the contrast
level
(LEBEL8) for resetting is adjusted with R19 to be optimum.
LCD
152X45(dot)
Microprocessor
1C4
Fig.16 Display circuit
@Dimmer circuit
The dimmer circuit switches the lamp brightness to one
of four levels or OFF.
(See Table 10.) The current flowing
to the LEDs is varied by selecting resistors from R55 to R58.
Dimmer level
P60
P61
P62
P63
1
H
L
L
L
2
L
H
L
L
3
L
L
H
L
4
L
L
L
H
OFF
L
L
L
L
Table10 Port logic
OV
LED1
LED2
LED3
LED4
IC4
£2
S tg a)
Microprocessor
Se
Se
Sr Fe
P60
Q13°
ont
P61
Wy K
Q12 >
{
P62
Wer "
Qi
om
P63
aa
' Fig.17 Dimmer circuit
M-V7A/E
17
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