Datasheet

Section 5 Clock Pulse Generators
Rev. 1.50 Sep. 18, 2007 Page 79 of 584
REJ09B0240-0150
[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 bit PMRJ0 stops the external oscillation.
LSI operates on external clock
Start
(LSI operates on external clock)
Write 0 to OSCSEL in CKCSR
LSI operates on
on-chip oscillator clock
Write 0 to RCSTP in RCCR
Write 1 to CKSWIE in CKCSR
if necessary
Write 0 to PMRJ0 in CKCSR
if necessary
LSI operates on
on-chip oscillator clock
When CKSWIE = 1
Wait until on-chip oscillator clock
settles (over 100 µs)
Figure 5.4 Flowchart of Clock Switching
(From External Clock to On-Chip Oscillator Clock)