2 POWER SUPPLY, RESET, AND CLOCKS
2-14
Seiko Epson Corporation
S1C31D50/D51 TECHNICAL MANUAL
(Rev. 2.00)
SLEEP mode
When the Cortex
®
-M0+ core executes the WFI or WFE instruction with the SLEEPDEEP bit of the system
control register set to 1, it suspends program execution and stops operating. This state is referred to SLEEP
mode in this IC. In this mode, the clock sources stop operating as well.
However, the clock source in which the CLGOSC.IOSCSLPC/OSC1SLPC/OSC3SLPC/EXOSCSLPC bit is set
to 0 keeps operating, so the peripheral circuits with the clock being supplied can also operate. By setting this
mode when no software processing and peripheral circuit operations are required, power consumption can be
less than HALT mode.
IOSC
RUN
OSC1
RUN
IOSC
HALT
OSC3
HALT
OSC3
RUN
RESET
(Initial state)
Transition takes place automatically by the
initial boot sequence after a request from
the reset source is canceled.
∗
In RUN and HALT modes, the clock sources not used
as SYSCLK can be all disabled.
HAL
T/SLEEP
cancelatio
n
signal
WFI/WFE
instr
uction
(SLEEPDEEP = 0)
RUN
SLEEP
WFI/WFE instruction
(SLEEPDEEP = 1)
HALT/SLEEP
cancelation signal
(wake-up)
WFI/WFE instr
uction
(SLEE
P
DEEP = 0)
HA
LT
/SLEEP
cancelation signal
CLGSCLK.CLKSRC[1:0] = 0x
1
CLGSCLK.CLKSRC[1:0] = 0x
0
EXOSC
RUN
CLGSCLK.CLKSRC[1:0] = 0x
2
CLGSCLK.CLKSRC[1:0] = 0x
3
CLGSCLK.CLKSRC[1:0] = 0x1
CLGSCLK.CLKSRC[1:0] = 0x3
OSC1
HALT
WFI/WFE instr
uction
(SLEEP
DEEP = 0)
HA
LT
/SLEEP
cancelation signal
EXOSC
HALT
HA
LT
/SLEEP
cancelation
signal
WFI/WFE
instr
uction
(SLEEPDEEP = 0)
CLGSCLK.CLKSRC[1:0] = 0x2
CLGSCLK.CLKSRC[1:0] = 0x0
CLGSCLK.CLKSRC[1:0] = 0x
0
CLGSCLK.CLKSRC[1:0] = 0x
3
CLGSCLK.CLKSRC[1:0] = 0x
1
CLGSCLK.CLKSRC[1:0] = 0x
2
Figure 2.4.2.1 Operating Mode-to-Mode State Transition Diagram
Canceling HALT or SLEEP mode
The conditions listed below generate the HALT/SLEEP cancelation signal to cancel HALT or SLEEP mode and
put the CPU into RUN mode.
• Interrupt request from a peripheral circuit
• NMI from the watchdog timer
• Reset request