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MDC
Encode. The MDC encoder is
part of the
sig-
nalling IC
(U700),
but is controlled by the
CORE
processor.
The
CORE
sends pulses
to
the
sig-
nalling
IC
that
clock
the signalling
IC's encoder.
The
encoded MDC signal contains instantaneous
frequencies
of
1200 Hz and 1800 Hz.
The signals
and
levels
to be
expected at various
pins of the
CORE
microcomputer
(U400) are as
follows:
Pin
No.
Function
Signal
Pin
No.
Function
Signal
Vss
Ground
Mode
B
5V
Mode
A
Ground
PD6
5V
No connection
Don't
care
5,6
E
XTAL
7.3728MHz signal (high-
impedance)
8,9
No connection
Don't
care
10
XTAL
7.3728MHz signal
11
AFIC
select
OV when
AFIC
is
being
programmed;
5V
otherwise
12
No connection
Don't
care
13
XMIT
power
ind.
OV or
5V
14
Busy
5V
Serial bus inactive;
OV
= Serial
bus active
15
Squelch
5V
Squeich detect;
OV
=
No squelch detect
16
Lock
detect
5V
Synthesizer
not
locked;
OV
Synthesizer locked
17
Fast
squelch
5V
= Squelch detect;
OV
No
squelch detect
18
Option switch
OV or
5V
19
Reset
OV =
Reset
mode;
5V
Otherwise
XtRQ
5 Volts
21
IRQ
5V
Serial bus data
5V
Bus inactive; Toggles
between OV and
5V
at
9600
baud when active
23, 24
No connection
Don't
care
25
Vss
Ground
No connection
Don't
care
27
Serial bus data
5V
= Bus Inactive; Toggles
between OV and
5V
at
9600
baud when active
MISO
5V =ICs
being programmed;
Toggles between
OV and
5V
at 115.2
kHz
when
!Cs
are
not
being programmed
MOSI
§V =!Cs
being programmed;
Toggles
between OV and
5V
at 115.2
kHz
when
ICs are
not
being programmed
SCK
5V =ICs
being programmed;
Toggles between
OV and
5V
at 115.2
kHz
when
ICs are
not
being programmed
31
No connection
Don't
care
Vdd
5V
Vss
Ground
PASF
Don't
care
Tone clock
out
Toggles between
OV and
5V
when
MDC
or tone signalling
is being transmitted
DTMF
clock
out
OV or
5V
37
AFIC
watchdog
5V
Normal operating mode;
disable
OV
Radio reset
in
progress
No connection
Don't
care
PL
sample clock
Toggles
between OV and
5V
at 1071Hz when
TPL
decode
is enabled; 537Hz when
DPL
decode is enabled.
12
times
TPL
frequency
(in transmit)
MDC
reference
Don't
care
41
PL
decode
Toggles between
OV and
5V
No connection
Don't
care
Limiter
in
Toggles between
OV and
5V
in
receive mode
No connection
Don't
care
Adapt
5V
During channel
change;
OV = Otherwise
D/A IC select
OV = When D/A
IC is being
programmed;
5V
Otherwise
47
Synthesizer IC
OV =
When synthesizer IC is
select
being programmed;
5V
Otherwise
Prescaler IC
OV
When prescaler IC is
select
being programmed;
5V
Otherwise
49
Signalling IC
OV
When signalling IC is
select
being programmed;
5V
Otherwise
Red
LED
5V
LED
on; OV
LED
off
51, 52
No connection
Don't
care
Freq. select 0
This
is the least-significant
bit
of the frequency switch. OV or
5V
Battery voltage
1/2 of
the battery
voltage
OV or
5V
Freq. select
1
Volume
sense
OV through
5V
57,
58
No connection
Don't
care
59
Freq. select 2
OV or
5V
Side
control
OV
PTT
switch pressed;
=.23V
Monitor button
pressed
61
Freq. select 3
This
is the most-significant
bit
of the frequency switch. OV or
5V
Option
select
5V
=
No option
connected;
23.73V =
Option
class
1;
=2,5V =
Option
class 2;
=1.23V
Option
class 3
VAL
Ground
VRH
5V
2
3
4
36
40
44
45
46
48
2
26
50
53
28
5
56
60
62
32
63
33
64
34
Note:
Ground
-0
volts
*
Needed
for
processor
to
power-up correctly.
8
e
MDC
Encode. The MDC encoder is
part of the
sig-
nalling IC
(U700),
but is controlled by the
CORE
processor.
The
CORE
sends pulses
to
the
sig-
nalling
IC
that
clock
the signalling
IC's encoder.
The
encoded MDC signal contains instantaneous
frequencies
of
1200 Hz and 1800 Hz.
The signals
and
levels
to be
expected at various
pins of the
CORE
microcomputer
(U400) are as
follows:
Pin
No.
Function
Signal
Pin
No.
Function
Signal
Vss
Ground
Mode
B
5V
Mode
A
Ground
PD6
5V
No connection
Don't
care
5,6
E
XTAL
7.3728MHz signal (high-
impedance)
8,9
No connection
Don't
care
10
XTAL
7.3728MHz signal
11
AFIC
select
OV when
AFIC
is
being
programmed;
5V
otherwise
12
No connection
Don't
care
13
XMIT
power
ind.
OV or
5V
14
Busy
5V
Serial bus inactive;
OV
= Serial
bus active
15
Squelch
5V
Squeich detect;
OV
=
No squelch detect
16
Lock
detect
5V
Synthesizer
not
locked;
OV
Synthesizer locked
17
Fast
squelch
5V
= Squelch detect;
OV
No
squelch detect
18
Option switch
OV or
5V
19
Reset
OV =
Reset
mode;
5V
Otherwise
XtRQ
5 Volts
21
IRQ
5V
Serial bus data
5V
Bus inactive; Toggles
between OV and
5V
at
9600
baud when active
23, 24
No connection
Don't
care
25
Vss
Ground
No connection
Don't
care
27
Serial bus data
5V
= Bus Inactive; Toggles
between OV and
5V
at
9600
baud when active
MISO
5V =ICs
being programmed;
Toggles between
OV and
5V
at 115.2
kHz
when
!Cs
are
not
being programmed
MOSI
§V =!Cs
being programmed;
Toggles
between OV and
5V
at 115.2
kHz
when
ICs are
not
being programmed
SCK
5V =ICs
being programmed;
Toggles between
OV and
5V
at 115.2
kHz
when
ICs are
not
being programmed
31
No connection
Don't
care
Vdd
5V
Vss
Ground
PASF
Don't
care
Tone clock
out
Toggles between
OV and
5V
when
MDC
or tone signalling
is being transmitted
DTMF
clock
out
OV or
5V
37
AFIC
watchdog
5V
Normal operating mode;
disable
OV
Radio reset
in
progress
No connection
Don't
care
PL
sample clock
Toggles
between OV and
5V
at 1071Hz when
TPL
decode
is enabled; 537Hz when
DPL
decode is enabled.
12
times
TPL
frequency
(in transmit)
MDC
reference
Don't
care
41
PL
decode
Toggles between
OV and
5V
No connection
Don't
care
Limiter
in
Toggles between
OV and
5V
in
receive mode
No connection
Don't
care
Adapt
5V
During channel
change;
OV = Otherwise
D/A IC select
OV = When D/A
IC is being
programmed;
5V
Otherwise
47
Synthesizer IC
OV =
When synthesizer IC is
select
being programmed;
5V
Otherwise
Prescaler IC
OV
When prescaler IC is
select
being programmed;
5V
Otherwise
49
Signalling IC
OV
When signalling IC is
select
being programmed;
5V
Otherwise
Red
LED
5V
LED
on; OV
LED
off
51, 52
No connection
Don't
care
Freq. select 0
This
is the least-significant
bit
of the frequency switch. OV or
5V
Battery voltage
1/2 of
the battery
voltage
OV or
5V
Freq. select
1
Volume
sense
OV through
5V
57,
58
No connection
Don't
care
59
Freq. select 2
OV or
5V
Side
control
OV
PTT
switch pressed;
=.23V
Monitor button
pressed
61
Freq. select 3
This
is the most-significant
bit
of the frequency switch. OV or
5V
Option
select
5V
=
No option
connected;
23.73V =
Option
class
1;
=2,5V =
Option
class 2;
=1.23V
Option
class 3
VAL
Ground
VRH
5V
2
3
4
36
40
44
45
46
48
2
26
50
53
28
5
56
60
62
32
63
33
64
34
Note:
Ground
-0
volts
*
Needed
for
processor
to
power-up correctly.
8
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