Table of Contents
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Pins
2 and 3 are the
MODB
and
MODA
inputs.
These
pins are tied high and low through
R512
and
R513, respectively;
they determine the mode that the
microcomputer
will be
in
after
it
is
reset.
MODB
must
be high and
MODA
must be low for the
COPE
to
oper-
ate
properly.
Pin 27 is an open drain output control
line for mut-
ing the microphone during
DTMF sequences.
Resistor
R527
is a pull-up resistor to
+5V. Transistor Q506
completes
the
bias current
path for the microphone,
which
is
located
on
the speaker/microphone flex.
When
pin
27
is high
(.7V), Q506
is
biased
on
and the
microphone is live; when
pin
27 is
low (OV),
Q506
is
off
and
no
microphone signal is produced.
The
actual
voltage
at
pin
27 can never go above .7V (one diode
drop).
Pins
33 and 34 form another
serial bus. The
COPE
uses
this bus
to
send serial clock and data
information to the
LCD
driver IC, U504, and,
on the
8k
board only,
to
DTMF
generator
IC U505.
The
bus
is
synchronous;
that is, one of the lines (pin 33) is
used
to
clock
the data
on
the other line (pin 34).
Resistor
R506
provides some isolation
on
the data line. During
data transfer, the receiving
|Cs
acknowledge data by
putting
a
low on the
data
line.
The
COPE
cannot
tri-
state
pin
34
or read the
acknowledge;
therefore,
R506
limits the current that
flows
if
the output
from pin
34 is
high.
Pins 46
through 53 are keypad input lines.
These
are high impedance lines and need
to
be pulled high
by resistors
R517
through
R524. The keypad
lines are
normally
all high
unless a key
is
pressed. Each key
causes
exactly
two of the lines to
go
low (row and
col-
umn).
The
COPE
decodes
the lines and
processes
the
keypress.
Pin 36 is
a high-impedance logic
input that is
con-
nected, via the
LCD
interconnect flex
(pin
8),
to
the
fast squelch
line on the main board
(U100,
pin
21).
The
fast squelch signal
is
used by the
COPE
during
scanning
to
detect the presence
of carrier.
j.
EEPROM
IC (U501)
Depending
on the
display circuit board,
U501 is
either a 2k
or an
8k
EEPROM
IC.
Besides
the
data
and
address lines already discussed
in
the
COPE
microcomputer section, U501 has four control lines,
which are
all
active
low; that is,
a
low on the pin acti-
vates
the
associated
function.
(1)
The
CC
(chip clear) line (pin 17) is an unused
input that is normally
used
to
erase
the entire
memory.
The
CC
pin is
tied high
to
the
Vdd
pin
(16), always
inhibiting this function.
The
CC
func-
tion
is
not
present
on
the 2k
EEPROM.
(2)
The
CE
(chip enable)
line (pin
7)
is
used
to
enable
the
EEPROM
for either read or write.
(3)
The
WE
(write-enable)
line (pin 15) is
used
with
the
CE
line
to
write
to
the
EEPROM.
Resistor
R502 ensures
that the
WE
line is held
inactive
during power-up and power-down so that inadver-
tent writes are avoided.
(4)
The
OE
(output
enable)
line (pin 11) is
used
with
the
CE
line to read from the
EEPROM.
The
OE
signal
causes
the data
I/O
pins (2 through 6, 30
through
32)
to
become
outputs.
k.
LCD
Driver IC (U504)
The LCD driver IC, U504, interfaces
with the
COPE
microcomputer
via a
2-wire synchronous bus
(pins 30 and 31).
The
COPE
sends
LCD
display data
over the bus
to the
LCD
driver.
The
driver
does
not
require "refreshing"; that is,
once the data has been
sent
to
the driver, the driver
will maintain
the display
without further
service
from the
COPE.
Only when
the
display requires changing does the
COPE
again com-
municate with the driver.
The
LCD
driver has
its own internal
clock, con-
trolled by resistor
R516,
which determines the frame
frequency
of the
driver waveforms. Pin
41
(VLCD)
is
used
to
set the driver
output level, which
affects
the
contrast, viewing angle, and segment crosstalk
of
the
display.
Resistors R507
and R511 set the
voltage
level
at
pin 41 to
about .5V, the optimum level
for
the type
of
LCD
being used.
The
lower the de voltage on
VLCD,
the greater the driver output level.
The LCD
driver outputs two types
of
waveforms
to
the
LCD:
backplane
and segment.
The
three back-
plane waveforms, output
from
pins 42 through 44, are
shown
in
the applicable
service
manual.
These signals
resemble "staircase" waveforms, and are displaced
apart
in
phase
from
each
other by 120
degrees. Four
discrete voltage levels are used: 0.5, 2.0, 3.5, and 5.0
volts;
voltages
that differ much from
these values
indi-
cate a
problem.
The
frequency
of
the
backplane wave-
forms should be
close
to
50 Hz.
The
other type
of
waveform, the segment driver
waveform, is sent
to the
LCD
via
pins
1
through 29,
and 45 through 56
(a
total of
40 segment waveforms).
Each segment
waveform drives three display
seg-
ments
(
the small lines
or
bars that make
up
the indi-
vidual
characters),
or
annunciator symbols (such
as
the battery symbol).
The actual appearance
of
the
segment waveforms depends
on
the data being dis-
played. Generally, the segment waveforms
will
contain
the
same voltage levels as
the
backplane waveforms
discussed above;
however, a segment waveform may
contain only two
of the four
levels (0.5V and
5.0V
or
2.0V
and
3.5V).
All four levels also may be seen.
The
display driver
is initialized at
power-up
with all
segments
and annunciators turned on. However, cer-
tain
annunciators may have been disabled through
programming; these annunciators will
not be
displayed.
|.
DTMF Generator IC (U505)
(8k circuit boards only)
The
dual-tone multi-frequency
(DTMF)
generator
IC, U505, generates
DTMF
tone pairs
for
transmission
over the
air.
The DTMF
generator IC interfaces (pins
20 and 23)
with the
COPE
over
the
same serial bus as
the
LCD
driver IC. To send a
message
to
the correct
destination, the
COPE
includes the bus address
of
the
desired IC
as
part of the communications protocol.
15
Pins
2 and 3 are the
MODB
and
MODA
inputs.
These
pins are tied high and low through
R512
and
R513, respectively;
they determine the mode that the
microcomputer
will be
in
after
it
is
reset.
MODB
must
be high and
MODA
must be low for the
COPE
to
oper-
ate
properly.
Pin 27 is an open drain output control
line for mut-
ing the microphone during
DTMF sequences.
Resistor
R527
is a pull-up resistor to
+5V. Transistor Q506
completes
the
bias current
path for the microphone,
which
is
located
on
the speaker/microphone flex.
When
pin
27
is high
(.7V), Q506
is
biased
on
and the
microphone is live; when
pin
27 is
low (OV),
Q506
is
off
and
no
microphone signal is produced.
The
actual
voltage
at
pin
27 can never go above .7V (one diode
drop).
Pins
33 and 34 form another
serial bus. The
COPE
uses
this bus
to
send serial clock and data
information to the
LCD
driver IC, U504, and,
on the
8k
board only,
to
DTMF
generator
IC U505.
The
bus
is
synchronous;
that is, one of the lines (pin 33) is
used
to
clock
the data
on
the other line (pin 34).
Resistor
R506
provides some isolation
on
the data line. During
data transfer, the receiving
|Cs
acknowledge data by
putting
a
low on the
data
line.
The
COPE
cannot
tri-
state
pin
34
or read the
acknowledge;
therefore,
R506
limits the current that
flows
if
the output
from pin
34 is
high.
Pins 46
through 53 are keypad input lines.
These
are high impedance lines and need
to
be pulled high
by resistors
R517
through
R524. The keypad
lines are
normally
all high
unless a key
is
pressed. Each key
causes
exactly
two of the lines to
go
low (row and
col-
umn).
The
COPE
decodes
the lines and
processes
the
keypress.
Pin 36 is
a high-impedance logic
input that is
con-
nected, via the
LCD
interconnect flex
(pin
8),
to
the
fast squelch
line on the main board
(U100,
pin
21).
The
fast squelch signal
is
used by the
COPE
during
scanning
to
detect the presence
of carrier.
j.
EEPROM
IC (U501)
Depending
on the
display circuit board,
U501 is
either a 2k
or an
8k
EEPROM
IC.
Besides
the
data
and
address lines already discussed
in
the
COPE
microcomputer section, U501 has four control lines,
which are
all
active
low; that is,
a
low on the pin acti-
vates
the
associated
function.
(1)
The
CC
(chip clear) line (pin 17) is an unused
input that is normally
used
to
erase
the entire
memory.
The
CC
pin is
tied high
to
the
Vdd
pin
(16), always
inhibiting this function.
The
CC
func-
tion
is
not
present
on
the 2k
EEPROM.
(2)
The
CE
(chip enable)
line (pin
7)
is
used
to
enable
the
EEPROM
for either read or write.
(3)
The
WE
(write-enable)
line (pin 15) is
used
with
the
CE
line
to
write
to
the
EEPROM.
Resistor
R502 ensures
that the
WE
line is held
inactive
during power-up and power-down so that inadver-
tent writes are avoided.
(4)
The
OE
(output
enable)
line (pin 11) is
used
with
the
CE
line to read from the
EEPROM.
The
OE
signal
causes
the data
I/O
pins (2 through 6, 30
through
32)
to
become
outputs.
k.
LCD
Driver IC (U504)
The LCD driver IC, U504, interfaces
with the
COPE
microcomputer
via a
2-wire synchronous bus
(pins 30 and 31).
The
COPE
sends
LCD
display data
over the bus
to the
LCD
driver.
The
driver
does
not
require "refreshing"; that is,
once the data has been
sent
to
the driver, the driver
will maintain
the display
without further
service
from the
COPE.
Only when
the
display requires changing does the
COPE
again com-
municate with the driver.
The
LCD
driver has
its own internal
clock, con-
trolled by resistor
R516,
which determines the frame
frequency
of the
driver waveforms. Pin
41
(VLCD)
is
used
to
set the driver
output level, which
affects
the
contrast, viewing angle, and segment crosstalk
of
the
display.
Resistors R507
and R511 set the
voltage
level
at
pin 41 to
about .5V, the optimum level
for
the type
of
LCD
being used.
The
lower the de voltage on
VLCD,
the greater the driver output level.
The LCD
driver outputs two types
of
waveforms
to
the
LCD:
backplane
and segment.
The
three back-
plane waveforms, output
from
pins 42 through 44, are
shown
in
the applicable
service
manual.
These signals
resemble "staircase" waveforms, and are displaced
apart
in
phase
from
each
other by 120
degrees. Four
discrete voltage levels are used: 0.5, 2.0, 3.5, and 5.0
volts;
voltages
that differ much from
these values
indi-
cate a
problem.
The
frequency
of
the
backplane wave-
forms should be
close
to
50 Hz.
The
other type
of
waveform, the segment driver
waveform, is sent
to the
LCD
via
pins
1
through 29,
and 45 through 56
(a
total of
40 segment waveforms).
Each segment
waveform drives three display
seg-
ments
(
the small lines
or
bars that make
up
the indi-
vidual
characters),
or
annunciator symbols (such
as
the battery symbol).
The actual appearance
of
the
segment waveforms depends
on
the data being dis-
played. Generally, the segment waveforms
will
contain
the
same voltage levels as
the
backplane waveforms
discussed above;
however, a segment waveform may
contain only two
of the four
levels (0.5V and
5.0V
or
2.0V
and
3.5V).
All four levels also may be seen.
The
display driver
is initialized at
power-up
with all
segments
and annunciators turned on. However, cer-
tain
annunciators may have been disabled through
programming; these annunciators will
not be
displayed.
|.
DTMF Generator IC (U505)
(8k circuit boards only)
The
dual-tone multi-frequency
(DTMF)
generator
IC, U505, generates
DTMF
tone pairs
for
transmission
over the
air.
The DTMF
generator IC interfaces (pins
20 and 23)
with the
COPE
over
the
same serial bus as
the
LCD
driver IC. To send a
message
to
the correct
destination, the
COPE
includes the bus address
of
the
desired IC
as
part of the communications protocol.
15
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