CHAPTER 5 CLOCK GENERATOR
Preliminary User’s Manual U16846EJ1V0UD
89
(6) Oscillation stabilization time select register (OSTS)
This register is used to select the oscillation stabilization wait time of the high-speed system clock when STOP
mode is released.
The wait time set by OSTS is valid only after STOP mode is released with the high-speed system clock selected
as the CPU clock. After STOP mode is released with Ring-OSC selected as the 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 0 0 0 0
OSTS2
OSTS1
OSTS0
Oscillation stabilization time selection
OSTS2 OSTS1 OSTS0
f
XP
= 10 MHz
f
XP
= 16 MHz
0 0 1
2
11
/f
XP
204.8
µ
s 128
µ
s
0 1 0
2
13
/f
XP
819.2
µ
s 512
µ
s
0 1 1
2
14
/f
XP
1.64 ms
1.02 ms
1 0 0
2
15
/f
XP
3.27 ms
2.04 ms
1 0 1
2
16
/f
XP
6.55 ms
4.09 ms
Other than above
Setting prohibited
Cautions 1. If the STOP mode is entered and then released while the Ring-OSC 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 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.
2. 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 f
XP
: High-speed system clock oscillation frequency