KCH-14/15
6
1-2. KCH-15
This display unit consists of the CPU (IC3), 5V AVR (IC1)
and other components.
• Encoder
Channels are changed by the rotary encoder (ENC). The
up/down pulses from the rotary encoder enter the CPU
(IC3), and converted to a serial data signal, and are sent to
the control unit.
• Power supply
Power is supplied to the CPU by converting SB from the
control unit to 5V by IC1. And SB is supplied for the LED of
backlight.
• CPU
The on/off signals of keys other than the power switch,
and the PTT and HOOK signals, are converted to serial data
and sent to the control unit. Data is displayed on the 14-digit
and 3-digit dot matrix alphanumeric display.
• LCD brightness function
From the control of the CPU’s DM1/DM2 port, you can
switch the LCD/KEY backlight or the optional KMC-28 key
backlight as shown in the following table.
LCD
LCD
KEY
KMC-28
brightness
setting
H
H
ON
ON
M
M
ON
ON
L
L
ON
ON
OFF
OFF
OFF
OFF
5V
AVR
LCD ASSY
SW
SW
SW
SW
SW
SW
SW
SW
REF
DM1 DM2
DM1 DM2
SB
KEY BACK LAMP
LCD BACK LAMP
S8
PF1
S9
PF2
S10
PF3
S14
PF4
S15
PF5
S5
MON
S6
PF6
S1
POWER
S7
PF7
S11
SCN
S12
PF8
S13
PF9
S2
S3
PTT
HK
D8
RX
D9
TX
AF VR
IC1
TA7805F
ENCODER
SB
HK
ME
MIC
E
TRD
DM
BLC
PTT
MIC
1/2
TRD
IRS
ES2
SB
PS
RESET
ED1
Containing
LCD driver IC
IC3
30302M84Z2GP
Microprocessor
Fig. 2
KCH-15 block diagram
CIRCUIT DESCRIPTION