Datasheet

Section 5 Clock Pulse Generators
Rev. 1.50 Sep. 18, 2007 Page 76 of 584
REJ09B0240-0150
5.2.4 Clock Control/Status Register (CKCSR)
CKCSR selects the OSC pin function, controls switching system clocks, and indicates the system
clock state. These bits must be written in active mode.
Bit Bit Name
Initial
Value R/W Description
7
6
PMRJ1
PMRJ0
0
0
R/W
R/W
OSC Pin Function Select 1 and 0
PMRJ1 PMRJ0 OSC2 OSC1
0 0 I/O I/O
1 0 CLKOUT I/O
0 1 Hi-Z OSC1 (external clock input)
1 1 OSC2 OSC1
5  0  Reserved
This bit is always read as 0.
4 OSCSEL 0 R/W LSI Operating Clock Select
This bit 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.
[Setting condition]
• When writing 1 while the CKSWIF bit is 0*
[Clearing condition]
• When writing 0
Note: * When the on-chip oscillator is in the standby
state (the RCTSP bit in RCCR is set to 1), do
not write 1 to this bit. When this bit is written to
1, the on-chip oscillator should be in operation.
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