Serial Mode Register - Hitachi SH7032 Hardware Manual

13.2.5

Serial Mode Register

The serial mode register (SMR) is an eight-bit register that specifies the SCI serial communication
format and selects the clock source for the baud rate generator.
The CPU can always read and write to SMR. SMR is initialized to H'00 by a reset and in standby
mode.
Bit:
Bit name:
Initial value:
R/W:
• Bit 7 (Communication Mode (C/A)): C/A selects whether the SCI operates in asynchronous or
synchronous mode.
Bit 7: C/A
0
1
• Bit 6 (Character Length (CHR)): CHR selects seven-bit or eight-bit data in asynchronous
mode. In synchronous mode, the data length is always eight bits, regardless of the CHR setting.
Bit 6: CHR
0
1
• Bit 5 (Parity Enable (PE)): PE selects whether to add a parity bit to transmit data and check the
parity of receive data, in asynchronous mode. In synchronous mode, a parity bit is neither
added nor checked, regardless of the PE setting.
Bit 5: PE
0
1
354
7 6
C/A CHR PE
0 0
R/W R/W R/W
Description
Asynchronous mode
Synchronous mode
Description
Eight-bit data
Seven-bit data. When seven-bit data is selected, the MSB (bit 7) of the
transmit data register is not transmitted.
Description
Parity bit not added or checked
Parity bit added and checked. When PE is set to 1, an even or odd
parity bit is added to transmit data, depending on the parity mode (O/E)
setting. Receive data parity is checked according to the even/odd (O/E)
mode setting.
5 4 3
O/E STOP
0 0 0
R/W R/W
2 1
MP CKS1 CKS0
0 0
R/W R/W R/W
(Initial value)
(Initial value)
(Initial value)
0
0