Icom IC-04A Service Manual page 14

MPU
PORT ALLOCATIONS
PORT
NUMBER
DO
[SEND]
D1 [MUTE]
D2
[CKJ
D3 [DATA]
D4[COMP]
D5 [UNLOCK]
D6
[PLL]
D7
[CTCSS]
D8
[SQL]
D9[HALT CONT]
DIO
[BEEP]
Dll [FUNC]
D12~D15[KEYSCAN]
RO
[KEY
RETURN]
R1 [INITIAL
KEY
RETURN]
R2
[INITIAL
KEY SCAN]
R3
[D/A]
INTO
[INT
0]
INTI [BAT]
RESET
[RESET]
PIN
NUMBER
DESCRIPTION
78
When
this
port
is
"LOW",
the transceiver
is
in
transmit
mode
and
inhibits
keyboard
entry.
79
This port remains
"HIGH"
for
approximately 60msec.
when
the
transceiver
is
changed from receive to transmit mode.
80
This port outputs
serial
CK
signals for
the
PLL and
subaudible
tone encoder
circuits.
This port outputs
serial
DATA
signals for
the
PLL and
subaudi-
ble
tone encoder
circuits.
When
this
port
is
"LOW"
the
number
of
R3
ports
is
indicated
on
the
S/RF
INDICATOR.
When
this
port
is
"LOW"
the
D1
port
is
made "LOW"
and
"U''
appears on
the
FREQUENCY
DISPLAY.
This port outputs a strobe
signal for
PLL
N-data.
This port outputs a strobe signal for the subaudible
tone
en-
coder.
When
this
port
is
"LOW",
scan
functions are
stopped and 2
dots
light
up on
the
S/RF
INDICATOR.
This port
remains
"LOW"
for a
few
milliseconds
when
it
turns
power ON.
It
selects
the address
in
the
MPU
and
makes
the
HLT
port
"HIGH".
This port remains
"HIGH"
for
40msec.
when
the
KEYBOARD
is
pushed
to control the
beep
oscillator.
When
this port
is
"LOW"
the secondary key function
is
selected.
10-13
These
are
output
ports for
keyboard scan and
are
connected
to
the
columns
of
the
KEYBOARD.
14-17
These
are input ports
for
the
keyboard scan from
ports
D12—
D15
and
are
connected
to
rows on
the
KEYBOARD.
66-69
These
are input ports
for
the
initial
matrix
key scan from
ports
R2
and determine frequency ranges, tuning step increments,
etc.
70-73
These
are
output
ports for the
initial
matrix
key
scan.
74-77
These
ports
output a loop counter
number
in
hexadecimal and
count up
until
the
COMP
port receives a
"LOW"
signal to
com-
pare
and
read
S/RF
voltage.
64
When
the transceiver
is
turned
OFF
this
port
is
"LOW"
and
the
HALT
CONT
port
remains
"HIGH"
for
a
few
milliseconds.
65
When
this port
is
"LOW",
the
BATTERY CONDITION
IN-
DICATOR
lights up.
18
When
this
port
is
"HIGH", the
MPU
is
initialized.
-7