Datasheet

Section 5 Clock Pulse Generators
Rev. 3.00 Sep. 14, 2006 Page 77 of 408
REJ09B0105-0300
[1]
[2]
Exception handling
for clock switching
[1] When 0 is written to the OSCSEL bit, this LSI
switches the external clock to the on-chip oscillator
clock after the φ stop duration. Seven rising edges
of the φ
RC
clock after the OSCSEL bit becomes 0
are included in the φ stop duration.
[2] Writing 0 to PMRC0 stops the external oscillation.
LSI operates on
external clock
Start
(LSI operates on external clock)
Write 0 to OSCSEL in CKCSR
Write 0 to RCSTP in RCCR
Write 1 to CKSWIE in CKCSR
if necessary
Write 0 to PMRC0 in CKCSR
if necessary
LSI operates on
on-chip oscillator clock
When CKSWIE = 1
LSI operates on on-chip
oscillator
Figure 5.4 Flowchart of Clock Switching External
Clock to On-chip Oscillator Clock (2)