SERIAL I/O
7905 Group User’s Manual Rev.1.0
11-42
11.4 Clock asynchronous serial I/O (UART) mode
Fig. 11.4.4 Initial setting example for relevant registers when transmitting
1
b7
b0
Transmission starts.
b7
b0
b7
b0
b7
b0
Transmit data is set.
b8
b7
b0
Internal/External clock select bit
1
b2 b1 b0
b7
b0
b15
0
Selection of clock synchronous serial
I/O mode
b7
b0
TxD0/P13 switch bit
0: Functions as TxD0.
TxD1/P17 switch bit
0: Functions as TxD1.
TxD2/P83 switch bit
0: Functions as TxD2.
CTSi/RTSi are used together.
i
CTSi/RTSi are separated.
0
b7
b0
0
b7
b0
0
UART0 transmit/receive mode register (Address 3016)
UART1 transmit/receive mode register (Address 3816)
UART2 transmit/receive mode register (Address B016)
0: Internal clock
1: External clock
UART0 transmit/receive control register 0 (Address 3416)
UART1 transmit/receive control register 0 (Address 3C16)
UART2 transmit/receive control register 0 (Address B416)
BRG count source select bits
b1 b0
0 0: f2
0 1: f16
0: CTS function selected
1 0: f64
1 1: f512
CTS/RTS function select bit
1: RTS function selected
0: CTS/RTS function is enabled.
CTS/RTS enable bit
1: CTS/RTS function is disabled
Serial I/O pin control register (Address AC16)
CTS0/RTS0 separate select bit
0: CTS0/RTS0 are used together.
1: CTS0/RTS0 are separated (Note).
1: CTS1/RTS1 are separated (Note).
CTS1/RTS1 separate select bit
0: CTS1/RTS1 are used together.
1: CTS2/RTS2 are separated (Note).
CTS2/RTS2 separate select bit
0: CTS2/RTS2 are used together.
UART0 baud rate register (BRG0) (Address 3116)
UART1 baud rate register (BRG1) (Address 3916)
UART2 baud rate register (BRG2) (Address B116)
Can be set to “0016” to “FF16”
Port P1 direction register (Address 516)
Pin CTS0
Pin CTS1
Port P8 direction register (Address 1416)
Pin CTS2
UART1 transmit interrupt control register (Address 7316)
UART0 transmit interrupt control register (Address 7116)
UART2 transmit interrupt control register (Address F116)
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.
UART0 transmit buffer register (Addresses 3316, 3216)
UART1 transmit buffer register (Addresses 3B16, 3A16)
(If the CTS function selected, transmission starts
when the CTSi pin’s input level becomes “L.”)
UART2 transmit buffer register (Addresses B316, B216)
UART0 transmit/receive control register 1 (Address 3516)
UART1 transmit/receive control register 1 (Address 3D16)
UART2 transmit/receive control register 1 (Address B516)
Transmit enable bit
1: Transmission enabled
Note: The CLKi pin cannot be used when
the CTSi/RTSi separation is selected.
(Refer to “[Precaution for clock
asynchronous serial I/O (UART)
mode].”)
1 0 0: UART mode (7 bits)
1 0 1: UART mode (8 bits)
1 1 0: UART mode (9 bits)
Stop bit length select bit
0: 1 stop bit
1: 2 stop bits
Odd/Even parity select bit
0: Odd parity
1: Even parity
Parity enable bit
0: Parity is disabled.
1: Parity is enabled.
Sleep select bit
0: Sleep mode cleared (invalid)
1: Sleep mode selected