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CHAPTER 13 UART
Table 13.4-1 Description of the Serial Mode Control Register (SMC) Bits
Bit name
Description
bit7
PEN: Parity enable bit
This bit selects whether the parity bit is to be added (at
transmission) and detected (at reception) when serial data is input/
output.
bit6
SBL: Stop bit length
selection bit
This bit selects the stop bit length for data to be transmitted.
Note:
When data is received, only the first bit of stop bits is detected
and the second and later bits are ignored.
bit5
bit4
MC1,MC0: Operating mode
selection bits
These bits specify operating mode (data length).
There are 7 types of data length selectable in combination with a
parity bit.
bit3
SMDE: Synchronization
mode selection bit
This bit specifies synchronous transfer or asynchronous transfer
mode.
When this bit is 0, synchronous transfer mode is set. When this
is 1, asynchronous transfer mode is set.
bit2
Unused bit
The value read out from this bit is undefined.
Writing a value into this bit does not affect any operations.
bit1
SCKE: Clock output enable
bit
This bit controls I/O of the serial clock.
When this bit is 0, P30/UCK/SCK terminal functions as the serial
clock input terminal. When this bit is 1, it functions as the serial
clock output terminal.
Notes:
When the UCK terminal functions as the serial clock input
terminal (SCKE = 0), set the P30/UCK/SCK terminal as the input
port. Also, select the external clock using the clock input
selection bit (SRC: CS1 and CS0 = 00B).
When the UCK terminal is set as the serial clock output terminal
(SCKE = 1), select a clock other than the external clock (SRC:
CS1 and CS0 must not be 00B).
Tip:
When the UCK terminal is specified as the serial clock output
(SCKE = 1), it functions as the UCK output terminal regardless
of the state of the general-purpose port (P30).
bit0
SOE: Serial data output
enable bit
When this bit is 0, the P31/UO/SO terminal functions as a general-
purpose port (P31). When this bit is 1, it functions as the serial
data output terminal (UO).
Tip:
When serial data output is enabled (SOE = 1), the terminal
functions as the UO terminal regardless of the state of the
general-purpose port (P31).