Datasheet

Section 5 Clock Pulse Generators
Rev. 3.00 Sep. 14, 2006 Page 74 of 408
REJ09B0105-0300
5.2.4 Clock Control/Status Register (CKCSR)
CKCSR selects the port C function, controls switching the system clocks, and indicates the system
clock state.
Bit Bit Name
Initial
Value R/W Description
7
6
PMRC1
PMRC0
0
0
R/W
R/W
Port C Function Select 1 and 0
PMRC1 PMRC0 PC1 PC0
0 0 I/O I/O
1 0 CLKOUT I/O
0 1 I/O OSC1 (external clock input)
1 1 OSC2 OSC1
5  0 R/W Reserved
Although this bit is readable/writable, it should not be set
to 1.
4 OSCSEL 0 R/W LSI Operation Clock Select
This bit forcibly selects the system clock of this LSI.
0: Selects the on-chip oscillator clock as the system clock.
1: Selects the external clock as the system clock.
3 CKSWIE 0 R/W Clock Switch Interrupt Enable
Setting this bit to 1 enables the clock switch interrupt
request.
2 CKSWIF 0 R/W Clock Switch Interrupt Request Flag
[Setting condition]
• When the external clock is switched to the on-chip
oscillator clock
[Clearing condition]
• When writing 0 after reading 1
1  1 R Reserved
This bit is always read as 1.
0 CKSTA 0 R LSI Operating Clock Status
0: This LSI operates on on-chip oscillator clock.
1: This LSI operates on external clock.