h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 336

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

11.4
Figure 11.2 shows the general format for asynchronous serial communication. One frame consists
of a start bit (low level), followed by transfer 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. In asynchronous serial communication, the
communication line is usually held in the mark state (high level). The SCI monitors the
communication 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.
Rev. 2.00, 03/04, page 304 of 534
Serial
data
1
Operation in Asynchronous Mode
Start
bit
1 bit
0
LSB
Figure 11.2 Data Format in Asynchronous Communication
D0
One unit of transfer data (character or frame)
(Example with 8-Bit Data, Parity, Two Stop Bits)
D1
D2
Transmit/receive data
D3
7 or 8 bits
D4
D5
D6
MSB
D7
Parity
bit
1 bit,
or none
0/1
Stop bit(s)
1
1 or
2 bits
1
Idle state
(mark state)
1