h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 411

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

13.4
Figure 13.2 shows the general format for asynchronous serial communication. One frame consists
of a start bit (low level), followed by data (in LSB-first order), a parity bit (high or low level), 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. When the
transmission line goes to the space state (low level), the SCI 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. Both the transmitter and the
receiver also have a double-buffered structure, so data can be read or written during transmission
or reception, enabling continuous data transfer.
13.4.1
Table 13.10 shows the data transfer formats that can be used in asynchronous mode. Any of 12
transfer formats can be selected according to the SMR setting. For details on the multiprocessor
bit, see section 13.5, Multiprocessor Communication Function.
Serial
data
Operation in Asynchronous Mode
Data Transfer Format
1
Start
bit
1 bit
0
Figure 13.2 Data Format in Asynchronous Communication
LSB
D0
(Example with 8-Bit Data, Parity, Two Stop Bits)
One unit of transfer data (character or frame)
D1
D2
Transmit/receive data
D3
7 or 8 bits
D4
D5
D6
Section 13 Serial Communication Interface (SCI)
MSB
D7
Rev. 2.00 Dec. 05, 2005 Page 373 of 724
Parity
bit
1 bit,
or none
0/1
1
Stop bit
1 or
2 bits
1
Idle state
(mark state)
REJ09B0200-0200
1