
Rev.3.02
Apr 10, 2008
REJ03B0177-0302
38D2 Group
Fig. 8 Switch procedure of CPU mode register
After releasing reset
N
Y
Low-speed/XIN mode ?
Start the oscillation
(bits 4 and 5 of CPUM)
Oscillator starts oscillation.
Do not change bit 3, bit 6 and bit 7
of CPUM until oscillation stabilizes.
Select internal system clock
(bit 3 of CPUM or bit 7, 6 = “01”)
Wait by on-chip oscillator operation until
establishment of oscillator clock
Switch the main clock division ratio
selection bit (bit 7, 6 = “00” or “10”)
Start with an on-chip oscillator.
Initial value of CPUM is E016.
Initial value of CPUM2 is 0016.
As for the details of condition for
transition among each mode,
refer to the state transition of
system clock.
System can operate in on-chip
oscillator mode until oscillation
stabilize.
Select internal system clock.
Do not change bit 3, bit 6 and bit
7 of CPUM at the same time.
Select main clock division ratio.
Switch to frequency/2 or frequency/4 mode here,
if necessary.
Main routine
Reset
L
OSCSEL ?
After releasing reset
Wait by operation until establishment
H
The CPU starts its operation
in the built-in XIN mode.
Initial value of CPUM is 4016.
Initial value of CPUM2 is 0116.
After releasing reset
N
Y
Low-speed/XIN mode ?
Start the oscillation
(bits 4 and 5 of CPUM)
Oscillator starts oscillation.
Do not change bit 3, bit 6 and bit 7 of CPUM until
oscillation stabilizes.
Select internal system clock
(bit 3 of CPUM or bit 7, 6 = “01”)
Wait by on-chip oscillator operation until
establishment of oscillator clock
Switch the main clock division ratio
selection bit (bit 7, 6 = “00” or “10”)
Start with an on-chip oscillator.
Initial value of CPUM is E016.
Initial value of CPUM2 is 0016.
As for the details of condition for
transition among each mode,
refer to the state transition of system clock.
System can operate in on-chip oscillator mode until
oscillation stabilize.
Select internal system clock.
Do not change bit 3, bit 6 and bit 7 of CPUM at the
same time.
Select main clock division ratio.
Switch to frequency/2 or 4 mode here, if necessary.
Main routine
Reset
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