Hitachi H8S/2646 Hardware Manual page 472

Bit 3—Stop Bit Length (STOP): Selects 1 or 2 bits as the stop bit length in asynchronous mode.
The STOP bits setting is only valid in asynchronous mode. If clocked synchronous mode is set the
STOP bit setting is invalid since stop bits are not added.
Bit 3
STOP Description
0 1 stop bit: In transmission, a single 1 bit (stop bit) is added to the end
1 2 stop bits: In transmission, two 1 bits (stop bits) are added to the end of a transmit
In reception, only the first stop bit is checked, regardless of the STOP bit setting. If the second
stop bit is 1, it is treated as a stop bit; if it is 0, it is treated as the start bit of the next transmit
character.
Bit 2—Multiprocessor Mode (MP): Selects multiprocessor format. When multiprocessor format
is selected, the PE bit and O/E bit parity settings are invalid. The MP bit setting is only valid in
asynchronous mode; it is invalid in clocked synchronous mode.
For details of the multiprocessor communication function, see section 13.3.3, Multiprocessor
Communication Function.
Bit 2
MP Description
0 Multiprocessor function disabled
1 Multiprocessor format selected
440
of a transmit character before it is sent.
character before it is sent.
(Initial value)
(Initial value)