UPD78F9202MA-CAC-A Datasheet, PDF (80/342 Pages) Renesas Technology Corp – 8-Bit Single-Chip Microcontrollers

CHAPTER 5 CLOCK GENERATORS
<R> (3) Oscillation stabilization time select register (OSTS) (μPD78F920x only)
This register is used to select oscillation stabilization time of the clock supplied from the oscillator when the STOP
mode is released. The wait time set by OSTS is valid only when the crystal/ceramic oscillation clock is selected
as the system clock and after the STOP mode is released. If the high-speed internal oscillator or external clock
input is selected as the system clock source, no wait time elapses.
The system clock oscillator and the oscillation stabilization time that elapses after power application or release of
reset are selected by the option byte. For details, refer to CHAPTER 15 OPTION BYTE.
OSTS is set by using an 8-bit memory manipulation instruction.
Figure 5-5. Format of Oscillation Stabilization Time Select Register (OSTS)
Address: FFF4H, After reset: Undefined, R/W
Symbol
7
6
5
4
3
2
1
0
OSTS
0
0
0
0
0
0
OSTS1
OSTS0
OSTS1
OSTS0
Selection of oscillation stabilization time
0
0
2¹⁰/fX (102.4 μs)
0
1
2¹²/fX (409.6 μs)
1
0
2¹⁵/fX (3.27 ms)
1
1
2¹⁷/fX (13.1 ms)
Cautions 1. To set and then release the STOP mode, set the oscillation stabilization time as
follows.
Expected oscillation stabilization time of resonator ≤ Oscillation stabilization time
set by OSTS
2. The wait time after the STOP mode is released does not include the time from the
release of the STOP mode to the start of clock oscillation (“a” in the figure
below), regardless of whether STOP mode was released by reset signal
generation or interrupt generation.
STOP mode is released
Voltage
waveform
of X1 pin
a
3. The oscillation stabilization time that elapses on power application or after release
of reset is selected by the option byte. For details, refer to CHAPTER 15 OPTION
BYTE.
Remarks 1. ( ): fX = 10 MHz
2. Determine the oscillation stabilization time of the resonator by checking the
characteristics of the resonator to be used.
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User’s Manual U18172EJ3V0UD