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Bits 1 and 0—Clock Select 1 and 0 (CKS1, CKS0): These bits select the clock source for the
baud rate generator. The clock source can be selected from ø, ø/4, ø/16, and ø/64, according to the
setting of bits CKS1 and CKS0.
For the relation between the clock source, the bit rate register setting, and the baud rate, see
section 13.2.8, Bit Rate Register (BRR).
Bit 1
Bit 0
CKS1
CKS0
0
0
1
1
0
1
13.2.6
Serial Control Register (SCR)
Bit
:
TIE
Initial value
:
R/W
:
R/W
SCR is a register that performs enabling or disabling of SCI transfer operations, serial clock output
in asynchronous mode, and interrupt requests, and selection of the serial clock source.
SCR can be read or written to by the CPU at all times.
SCR is initialized to H'00 by a reset and in standby mode.
Bit 7—Transmit Interrupt Enable (TIE): Enables or disables transmit data empty interrupt
(TXI) request generation when serial transmit data is transferred from TDR to TSR and the TDRE
flag in SSR is set to 1.
Bit 7
TIE
Description
0
Transmit data empty interrupt (TXI) requests disabled*
1
Transmit data empty interrupt (TXI) requests enabled
Note:* TXI interrupt request cancellation can be performed by reading 1 from the TDRE flag, then
clearing it to 0, or clearing the TIE bit to 0.
Description
ø clock
ø/4 clock
ø/16 clock
ø/64 clock
7
6
5
RIE
TE
0
0
0
R/W
R/W
4
3
RE
MPIE
TEIE
0
0
R/W
R/W
R/W
(Initial value)
2
1
0
CKE1
CKE0
0
0
0
R/W
R/W
(Initial value)
441
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