Datasheet
78K0/Ix2 CHAPTER 5 CLOCK GENERATOR
R01UH0010EJ0500 Rev.5.00 165
Feb 28, 2012
(7) Oscillation stabilization time select register (OSTS)
This register is used to select the X1 clock oscillation stabilization wait time when the STOP mode is released.
When the X1 clock is selected as the CPU clock, the operation waits for the time set using OSTS after the STOP
mode is released.
When the internal high-speed oscillation clock is selected as the CPU clock, confirm with OSTC that the desired
oscillation stabilization time has elapsed after the STOP mode is released. The oscillation stabilization time can be
checked up to the time set using OSTC.
OSTS can be set by an 8-bit memory manipulation instruction.
Reset signal generation sets OSTS to 05H.
Figure 5-8. 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
OSTS2 OSTS1 OSTS0 Oscillation stabilization time selection
fX = 10 MHz
0 0 1 2
11
/fX 204.8
s
0 1 0 2
13
/fX 819.2
s
0 1 1 2
14
/fX 1.64 ms
1 0 0 2
15
/fX 3.27 ms
1 0 1 2
16
/fX 6.55 ms
Other than above Setting prohibited
Cautions 1. To set the STOP mode when the X1 clock is used as the CPU clock, set OSTS before
executing the STOP instruction.
2. Do not change the value of the OSTS register during the X1 clock oscillation
stabilization time.
3. The oscillation stabilization time counter counts up to the oscillation stabilization
time set by OSTS. If the STOP mode is entered and then released while the internal
high-speed 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
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 X1 clock oscillation stabilization wait time does not include the time until clock
oscillation starts (“a” below).
STOP mode release
X1 pin voltage
waveform
a
Remark f
X: X1 clock oscillation frequency