7540 Group User
’
s Manual
APPLICATION
2-107
2.6 Serial I/O1
Fig. 2.6.10 Setting method for clock synchronous serial I/O1 (1)
In
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1
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I
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1
)
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S
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I
I
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(
B
R
G
)
[
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6
]
Set baud rate value
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7
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0 0
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1
:
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I
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O
.
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I
/
O
1
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g
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(
S
I
O
1
C
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N
)
[
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A
1
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]
T
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0
BRG count source selected (set in internal clock selected)
0: f(X
IN
)
1: f(X
IN
)/4
Serial I/O1 synchronous clock selected
0: BRG output/4 (
Note 1
)
1: External clock input
S
RDY1
output enable selected
0: P1
3
pin operates as normal I/O pin
1: P1
3
pin operates as S
RDY1
output pin (
Note 2
)
Transmit interrupt source selected
0: When transmit buffer has emptied
1: When transmit shift operation is completed
Transmit enable selected
0: Transmit disabled (at half-duplex communication receive)
1: Transmit enabled (at full-duplex communication) (
Note 3
)
Receive enable selected
0: Receive disabled (at half-duplex communication transmit)
1: Receive enabled (at full-duplex communication) (
Note 3
)
Clock synchronous serial I/O
Serial I/O1 enabled
(P1
0
–
P1
3
pins operate as serial I/O1 pins)
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I
/
O
1
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(
S
I
O
1
C
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)
[
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]
P
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:
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/
O
1
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.
b
1 1
7
b
0
Notes 1:
Setting of serial I/O1 synchronous selection bit is as follows:
“
0
”
: P1
2
pin is set to be an output pin of the synchronous clock.
“
1
”
: P1
2
pin is set to be an input pin of the synchronous clock.
2:
When an external clock input is selected as the synchronous clock, and the receiver
performs the S
RDY1
output, set
“
1
”
to the transmit enable bit in addition to the receive
enable bit and S
RDY1
output enable bit.
3:
When data transmission is executed at the state that an external clock input is
selected as the synchronous clock, set
“
1
”
to the transmit enable bit while the S
CLK1
is
“
H
”
state.
P
r
o
c
e
s
s
2
:
D
i
s
a
b
l
e
s
e
r
i
a
l
I
/
O
1
t
r
a
n
s
m
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t
/
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e
c
e
i
v
e
i
n
t
e
r
r
u
p
t
.
Process 4: When BRG output/4 is selected as synchronous clock, set value to baud rate generator.
(2) Clock synchronous serial I/O setting method
Figure 2.6.10 and Figure 2.6.11 show the setting method for the clock synchronous serial I/O1.