
CHAPTER 5 CLOCK GENERATOR
User’s Manual U16315EJ3V1UD
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(6) Oscillation stabilization time select register (OSTS)
This register is used to select the X1 oscillation stabilization wait time when STOP mode is released.
The wait time set by OSTS is valid only after STOP mode is released with the X1 input clock selected as CPU
clock. After STOP mode is released with the internal oscillation clock selected as CPU clock, the oscillation
stabilization time must be confirmed by OSTC.
OSTS can be set by an 8-bit memory manipulation instruction.
RESET input sets OSTS to 05H.
Figure 5-7. Format of Oscillation Stabilization Time Select Register (OSTS)
Address: FFA4H
After reset: 05H
R/W
Symbol
7
6
5
4
3
2
1
0
OSTS
0
OSTS2
OSTS1
OSTS0
OSTS2
OSTS1
OSTS0
Oscillation stabilization time selection
When fXP = 10 MHz
When fXP = 12 MHz
Note
0
1
2
11/fXP
204.8
s
170.7
s
0
1
0
2
13/fXP
819.2
s
682.7
s
0
1
2
14/fXP
1.64 ms
1.37 ms
1
0
2
15/fXP
3.27 ms
2.73 ms
1
0
1
2
16/fXP
6.55 ms
5.46 ms
Other than above
Setting prohibited
Note Expanded-specification products of standard products and (A) grade products only
Cautions 1. To set the STOP mode while the X1 input clock is used as the CPU clock, set
OSTS before executing the STOP instruction.
2. Before setting OSTS, confirm with OSTC that the desired oscillation stabilization
time has elapsed.
3. If the STOP mode is entered and then released while the internal oscillation
clock is being used as the CPU clock, set the oscillation stabilization time as
follows.
Desired OSTC oscillation stabilization time ≤ Oscillation stabilization time
set by OSTS
The X1 oscillation stabilization time counter counts up to the oscillation
stabilization time set by OSTS. Note, therefore, that only the status up to the
oscillation stabilization time set by OSTS is set to OSTC after STOP mode is
released.
4. The wait time when STOP mode is released does not include the time after STOP
mode release until clock oscillation starts (“a” below) regardless of whether
STOP mode is released by RESET input or interrupt generation.
STOP mode release
X1 pin voltage
waveform
a
Remark
fXP: X1 input clock oscillation frequency