SERIAL I/O
7902 Group User’s Manual
12-29
12.3 Clock synchronous serial I/O mode
Fig. 12.3.8 Initial setting example for relevant registers when receiving
0
UART0 transmit/receive mode register (Address 3016)
UART1 transmit/receive mode register (Address 3816)
b7
b0
Internal/External clock select bit
0: Internal clock
1: External clock
!
!!
!: It may be either “0” or “1.”
Selection of clock synchronous serial
I/O mode
UART0 transmit/receive control register 0 (Address 3416)
UART1 transmit/receive control register 0 (Address 3C16)
b7
b0
BRG count source select bits
CTS/RTS function select bit
0: CTS function selected
1: RTS function selected
0 0 : f2
0 1 : f16
1 0 : f64
1 1 : f512
b1 b0
Reception starts.
UART0 transmit buffer register (Address 3216)
UART1 transmit buffer register (Address 3A16)
b7
b0
Dummy data is set.
1
UART0 transmit/receive control register 1 (Address 3516)
UART1 transmit/receive control register 1 (Address 3D16)
b7
b0
Transmit enable bit
1: Transmission enabled
UART0 receive interrupt control register (Address 7216)
UART1 receive interrupt control register (Address 7416)
b7
b0
Interrupt priority level select bits
When using interrupts, set these bits to
one of levels 1 to 7.
When disabling interrupts, set these bits
to level 0.
CTS/RTS enable bit
0: CTS/RTS function is enabled.
1: CTS/RTS function is disabled.
CLK polarity select bit
0: At the rising edge of the transfer
clock, receive data is input.
1: At the falling edge of the transfer
clock, receive data is input.
Transfer format select bit
0: LSB first
1: MSB first
When extenal clock is selected
UART0 baud rate register (BRG0) (Address 3116)
UART1 baud rate register (BRG1) (Address 3916)
b7
b0
Can be set to “0016” to “FF16.”
When internal clock is selected
UARTi receive interrupt mode select bit
0: Reception interrupt
1: Reception error interrupt
0
Port P8 direction register (Address 1416)
b7
b0
Pin RxD0
Pin RxD1
1
Reception enable bit
1: Reception enabled
Note: Set the receive enable bit
and the transmit enable
bit to “1” simultaneously.
1
0
Serial I/O pin control register (Address AC16)
b7
b0
CTS0/RTS0 separate select bit
0: CTS0/RTS0 are used together (Note 1).
Notes 1: In the clock synchronous serial I/O
mode, CTSi/RTSi separation cannot
be selected. (Refer to section “[Pre-
cautions for clock synchronous
serial I/O mode].”)
2: When only reception is performed, if
these bits = “1,” the TxDi pin can be
used as a programmable I/O port
pin.
CTS1/RTS1 separate select bit
0: CTS1/RTS1 are used together (Note 1).
TxD0/P83 switch bit (Note 2)
0: Functions as TxD0.
1: Functions as P83.
TxD1/P87 switch bit (Note 2)
0: Functions as TxD1.
1: Functions as P87.