HD64F3337YCP16V Datasheet, PDF (577/749 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

22.3.4 Sample Application of Software Standby Mode
In this example the chip enters the software standby mode when NMI goes low and exits when
NMI goes high, as shown in figure 22.1.
The NMI edge bit (NMIEG) in the system control register is originally cleared to 0, selecting the
falling edge. When NMI goes low, the NMI interrupt handling routine sets NMIEG to 1, sets
SSBY to 1 (selecting the rising edge), then executes the SLEEP instruction. The chip enters
software standby mode. It recovers from software standby mode on the next rising edge of NMI.
Clock
oscillator
ø
NMI
NMIEG
SSBY
NMI interrupt
handler
NMIEG = 1
SSBY = 1
Software standby
mode (power-
down state)
SLEEP instruction
Settling time
NMI interrupt
handler
Figure 22.1 NMI Timing in Software Standby Mode (Application Example)
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