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7.3 Clock synchronous serial I/O mode
Table 7.3.1 lists the performance overview in the clock synchronous serial I/O mode, and Table 7.3.2 lists
the functions of I/O pins in this mode.
Table 7.3.1 Performance overview in clock synchronous serial I/O mode
Item
Transfer data format
Transfer rate
When selecting internal clock
When selecting external clock
Transmit/Receive control
Table 7.3.2 Functions of I/O pins in clock synchronous serial I/O mode
Pin name
TxD
(P8
, P8
)
Serial data output
i
3
7
RxD
(P8
, P8
)
Serial data input
i
2
6
CLK
(P8
, P8
)
Transfer clock output
i
1
5
Transfer clock input
____
CTS input
CTS
/RTS
i
i
____
(P8
, P8
)
0
4
RTS output
Port P8 direction register
Internal/External clock select bit
____ ____
CTS/RTS select bit
3
: bit 2 at addresses 34
Notes 1: The TxD
pin outputs "H" level until transmission starts after UARTi's operating mode is selected.
i
2: The RxD
pin can be used as a programmable I/O port when performing only transmission.
i
Transfer data has a length of 8 bits.
LSB first or MSB first can be selected by software.
Clock which is BRGi output's divided by 2.
Maximum 5 Mbps
____
CTS function or RTS function can be selected by software.
Functions
Fixed
(Dummy data is output when performing only reception.)
Port P8 direction register
Internal/External clock select bit
Internal/External clock select bit = "1"
____ ____
CTS/RTS select bit
____ ____
CTS/RTS select bit = "1"
1
: Address 14
16
2
: bit 3 at addresses 30
, 3C
16
7751 Group User's Manual
7.3 Clock synchronous serial I/O mode
Functions
____
Method of selection
1
's corresponding bit = "0"
3
= "0"
, 38
16
16
16
SERIAL I/O
2
= "0"
7–17
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