CHAPTER 5 CLOCK GENERATOR
Preliminary User’s Manual U16846EJ1V0UD
98
Figure 5-14. Status Transition Diagram (2/2)
(2) When “Ring-OSC cannot be stopped” is selected by option byte
Status 3
CPU clock: f
XP
f
XP
: Oscillating
f
R
: Oscillating
HALT
Interrupt
Interrupt
Interrupt
STOP
instruction
MCM0 = 0
MCM0 = 1
Note 1
HALT
instruction
HALT
instruction
STOP
Note 3
Reset
Note 4
Status 2
CPU clock: f
R
f
XP
: Oscillating
f
R
: Oscillating
Status 1
CPU clock: f
R
f
XP
: Oscillation stopped
f
R
: Oscillating
Interrupt
STOP
instruction
Interrupt
Interrupt
STOP
instruction
MSTOP = 1
Note 2
MSTOP = 0
HALT instruction
Reset release
Notes 1. Before shifting from status 2 to status 3 after reset and STOP are released, check the high-speed
system clock oscillation stabilization time status using the oscillation stabilization time counter status
register (OSTC).
Waiting for the oscillation stabilization time is not required when the external RC oscillation clock is
selected as the high-speed system clock by the option byte. Therefore, the CPU clock can be
switched without reading the OSTC value.
2. When shifting from status 2 to status 1, make sure that MCS is 0.
3. The watchdog timer operates using Ring-OSC even in STOP mode if “Ring-OSC cannot be stopped”
is selected by the option byte. Ring-OSC division can be selected as the count source of 8-bit timer
H1 (TMH1), so clear the watchdog timer using the TMH1 interrupt request before watchdog timer
overflow. If this processing is not performed, an internal reset signal is generated at watchdog timer
overflow after STOP instruction execution.
4. All reset sources (RESET input, POC, LVI, clock monitor, and WDT)