Hitachi H8/3637 Hardware Manual page 244

 When an external clock is selected: The internal baud rate generator is not used.
Operation is synchronous with the input clock.
Table 10.11 SMR Settings and SCI3 Communication Format
SMR Setting
Bit 7: Bit 6: Bit 2: Bit 5:
COM CHR MP PE
0 0 0 0
1
1 0
1
0 1
*
*
1 *
*
1 * 0 *
Note: * Don't care
240
Bit 3:
STOP Mode
0 Asynchronous
mode
1
0
1
0
1
0
1
0 Asynchronous
mode
1
(multiprocessor
0
format)
1
* Synchronous
mode
Communication Format
Multipro-
Data Length cessor Bit
8-bit data None
7-bit data
8-bit data Yes
7-bit data
8-bit data None
Parity Stop Bit
Bit Length
None 1 bit
2 bits
Yes 1 bit
2 bits
None 1 bit
2 bits
Yes 1 bit
2 bits
None 1 bit
2 bits
1 bit
2 bits
None None