REV.-A
2.3.1
Handshaking
Between
Main
CPU and
Sub-CPUs
The three CPUs operate using a
clock
supplied
from
a gate array (GAH40D),
which
has a
built-in
frequency
divider
circuit. Data and
commands
are exchanged
between
the
main
CPU and
the
two
sub-CPUs as
follow:
l
Gate
•
Main
CPU
K
P,,,lIelt,,",'e,
)
II
\
(l80)
array
Serial transfer
1\
J
Sub-CPU
7508
GAH40M
, "
'4
...
~~I
I
QjID
-
....
-rJ)
~
C
co co
<;-.-?-
I
LCD
controller
Gate array
....
f.E----
SED1320
.....
GAH40D
..c::;:
~
]1~
-rJ)
~
C
COCO
0..;-
~7'1t
Slave
CPU
6303
Data exchange between
l80
and
6303:
Handshaking is accomplished via the
LCD
controller.
Data exchange between
l80
and
7508:
Handshaking is accomplished via the gate array
GAH40M.
Fig.2-25
Data/Command
Exchange
Between
Main
CPU
and
Sub-CPUs
2.3.1.1
Data/Command
Exchange
Between
Main
CPU
and
Sub-CPU
7508
via
GAH40M
Commands
are transferred in parallell
between
the
main
CPU
and gate array and serially
between
the
gate array and sub-CPU
7508.
Handshaking
among
the
CPUs is
performed
via
the
read/write
control
on
the
serial/parallel conversion register in
the
gate array. Fig.
2-26
illustrates
this
control.
Main
CPU
Gate array (GAH40M)
Sub
CPU
l-80
l;1
1\
......-
Sl
so
7508
8-bit
data bus
.\
SID
f\
vi
R
CK
so
S1;.,
•
14:
SCK
...
...
L-W
IT~
P20
..
P22
..
.~
--.
I/O resistor
P21
~
CS
06
R
7001
~
SI
L----
so
I
Fig.
2-26
Main
CPU
and
7508
Handshaking
Control
2-30
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