h8s-2111b Renesas Electronics Corporation., h8s-2111b Datasheet - Page 283

• Manufacturer Part Number: h8s-2111b
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

12.3.10 Serial Pin Select Register (SPSR)
SPSR selects the serial I/O pins. SPSR should be set before initialization. Do not set during
communication.
Note: The program development tool (emulator) does not support SPSR.
12.4
Figure 12.2 shows the general format for asynchronous serial communication. One frame consists
of a start bit (low level), followed by transmit/receive data, a parity bit, and finally stop bits (high
level). In asynchronous serial communication, the transmission line is usually held in the mark
state (high level). The SCI monitors the transmission line, and when it goes to the space state (low
level), recognizes a start bit and starts serial communication. Inside the SCI, the transmitter and
receiver are independent units, enabling full-duplex communication. Both the transmitter and the
receiver also have a double-buffered structure, so that data can be read or written during
transmission or reception, enabling continuous data transfer and reception.
Bit
7
6 to 0
Serial
data
Operation in Asynchronous Mode
Bit
Name
SPS1
—
1
Start
bit
1 bit
Figure 12.2 Data Format in Asynchronous Communication
0
LSB
Initial
Value
0
All 0
D0
(Example with 8-Bit Data, Parity, Two Stop Bits)
One unit of transfer data (character or frame)
D1
R/W
R/W
R/W
D2
Transmit/receive data
D3
7 or 8 bits
Description
Serial Port Select
Selects the serial I/O pins.
0: P86/SCK1, P85/RxD1, P84/TxD1
1: P52/ExSCK1, P51/ExRxD1, P50/ExTxD1
Reserved
The initial value should not be changed.
D4
D5
D6
MSB
D7
Parity
bit
1 bit or
none
Rev. 1.00, 05/04, page 249 of 544
0/1
Stop bit
1
1 or 2 bits
1
(mark state)
Idle state
1