Bits 1 and 0: Clock select 1, 0 (CKS1, CKS0)
Bits 1 and 0 choose ø/64, ø/16, ø/2, or ø as the clock source for the baud rate generator.
For the relation between the clock source, bit rate register setting, and baud rate, see 8, Bit rate
register (BRR).
Bit 1
Bit 0
CKS1
CKS0
Description
ø clock
øW/2 clock*1/øW clock*2
0
0
1
1
0
1
0
1
(initial value)
ø/16 clock
ø/64 clock
Notes: 1. øW/2 clock is selected in active (medium- and high-speed) or sleep (medium- and high-
speed) mode.
2. øW clock is selected in subactive or subsleep mode. SCI3 can be used only when the
øW/2 is selected as the CPU clock in subactive or subsleep mode.
6. Serial control register 3 (SCR3)
Bit
7
TIE
0
6
RIE
0
5
TE
0
4
RE
0
3
MPIE
0
2
TEIE
0
1
CKE1
0
0
CKE0
0
Initial value
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
SCR3 is an 8-bit register for selecting transmit or receive operation, the asynchronous mode clock
output, interrupt request enabling or disabling, and the transmit/receive clock source.
SCR3 can be read or written by the CPU at any time.
SCR3 is initialized to H'00 upon reset, and in standby, watch or module standby mode.
275
ETC [ ETC ]
