Cypress FM4 Series - Page 213

CHAPTER 6: Low Power Consumption Mode
FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E 213
Return from Stop Mode
The CPU returns from STOP mode in one of the following situations.
 Return due to reset
If a reset (INITX pin input reset or low voltage detection reset) occurs, the CPU switches to high speed
CR run mode regardless of the clock mode.
In Stop mode, since the software watchdog reset, the hardware watchdog reset, the clock supervisor
reset and the anomalous frequency detection reset are not available, these resets cannot be used to
make the CPU return from Stop mode.
 Return due to interrupt
On receiving a request for an effective interrupt, which can be an NMI interrupt, an external interrupt, a
USB wakeup interrupt, a watch counter interrupt or a low voltage detection interrupt, in Stop mode, the
CPU returns from Stop mode and transits to a Run mode corresponding to the clock mode indicated in
the RCM[2:0] bits in the System Clock Mode Status Register (SCM_STR).
Table 3-9 Operation Mode after Return from Stop Mode due to Interrupt
Status of Master Clock before Transition to Stop Mode
RCM = 000
(High Speed CR
Oscillator)
RCM = 001
(Main Oscillator)
RCM = 010
(PLL Oscillator)
RCM = 100
(Low Speed CR
Oscillator)
RCM = 101
(Sub Oscillator)
Operation mode after
return due to interrupt
High speed CR
run mode
Main run mode
PLL run mode
Low speed CR run
mode
Sub run mode
 Oscillation stabilization wait at return
On returning from Stop mode due to a reset, the CPU waits for the stabilization of high speed CR clock
oscillation and that of low speed CR clock oscillation. If the CPU returns from Stop mode due to an
interrupt, the oscillation stabilization wait changes according to the master clock that had been used
before the CPU transited to Stop mode. Table 3-10 shows the relationship between the oscillation
stabilization wait and the master clock.
Table 3-10 Oscillation Stabilization Wait at Return from Stop Mode due to Interrupt
Status of Master Clock before Transition to Stop Mode
RCM = 000
(High Speed CR
Oscillator)
RCM = 001
(Main Oscillator)
RCM = 010
(PLL Oscillator)
RCM = 100
(Low Speed CR
Oscillator)
RCM = 101
(Sub Oscillator)
Oscillation stabilization wait at return
due to interrupt
High speed
CR clock
Yes
No
Main clock
MOSCE = 0 : No
MOSCE = 1 : Yes
Yes
PINC = 0 : Yes
PINC = 1 : No
No
Main PLL
clock
No
PLLE = 0 : No
PLLE = 1 : Yes
Yes
No
Low speed
CR clock
Yes
Sub clock
SOSCE = 0 : No
SOSCE = 1 : Yes
SOSCE = 0 : No
SOSCE = 1 : Yes
SOSCE = 0 : No
SOSCE = 1 : Yes
SOSCE = 0 : No
SOSCE = 1 : Yes
Yes