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13.3.5
Serial Mode Register (SMR)
SMR is used to set the SCI's serial transfer format and select the baud rate generator clock source.
Bit
Bit Name Initial Value
7
C/A
0
6
CHR
0
5
PE
0
4
O/E
0
3
STOP
0
2
MP
0
R/W
Description
R/W
Communication Mode
0: Asynchronous mode
1: Clocked synchronous mode
R/W
Character Length (enabled only in asynchronous mode)
0: Selects 8 bits as the data length.
1: Selects 7 bits as the data length. LSB-first is fixed
and the MSB of TDR is not transmitted.
In clocked synchronous mode, a fixed data length of 8
bits is used.
R/W
Parity Enable (enabled only in asynchronous mode)
When this bit is set to 1, the parity bit is added to
transmit data before transmission, and the parity bit is
checked in reception. For a multiprocessor format, parity
bit addition and checking are not performed regardless
of the PE bit setting.
R/W
Parity Mode (enabled only when the PE bit is 1 in
asynchronous mode)
0: Selects even parity.
1: Selects odd parity.
R/W
Stop Bit Length (enabled only in asynchronous mode)
Selects the stop bit length in transmission.
0: 1 stop bit
1: 2 stop bits
In reception, only the first stop bit is checked. If the
second stop bit is 0, it is treated as the start bit of the
next transmit character.
R/W
Multiprocessor Mode (enabled only in asynchronous
mode)
When this bit is set to 1, the multiprocessor
communication function is enabled. The PE bit and O/E
bit settings are invalid in multiprocessor mode.
Rev. 3.0, 10/02, page 363 of 686
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