HD64336901G Renesas Technology, HD64336901G Datasheet - Page 101

• Manufacturer Part Number: HD64336901G
• Description: (HD64xxx Series) 16-BIT MICROCONTROLLER
• Manufacturer: Renesas Technology

LSI operates on external oscillator
Figure 5.4 Flowchart of Clock Switching with Backup Function Disabled (1)
Write 1 to OSCSEL in CKCSR
Write 0 to CKSWIE in CKCSR
Write 1 to PMRC0 in CKCSR
Write 1 to PMRC1 in CKCSR
external clock? (CKSTA in
LSI operates on internal RC clock
Start (reset)
CKCSR is 1)
Switched to
Yes
(From Internal RC Clock to External Clock)
No
[1]
[2]
[3]
[1] External oscillation starts when pins PC1 and PC0
[2] After writing 1 to the OSCSEL bit, this LSI waits
[3] While the system is waiting for the external
are selected as external oscillation pins. Write 0 to
bit PMRC1 to input the external clock.
until the oscillation of the external oscillator
settles. The correspondence between Nwait,
which is the number of wait cycles for oscillation
settling, and Nstby, which is the number of wait
cycles for oscillation settling when returning from
standby mode, is as follows:
Nstby
Nstby is set by bits STS[2:0] in SYSCR1.
For details, see section 6.1.1, System Control
Register 1 (SYSCR1).
oscillation settling, this LSI is not halted but
continues to operate on the internal RC clock.
Read the value of the CKSTA bit in CKCSR to
ensure that the system clocks are switched.
Nwait
Rev. 1.00, 11/03, page 73 of 376
2
Nstby