SH7125_08 Datasheet, PDF (693/774 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 19 Power-Down Modes
19.5.2 Canceling Software Standby Mode
Software standby mode is canceled by interrupts (NMI, IRQ) or a reset.
(1) Canceling with Interrupt
The WDT can be used for hot starts. When an NMI or IRQ interrupt (edge detection) is detected,
the clock will be supplied to the entire LSI and software standby mode will be canceled after the
time set in the timer control/status register of the WDT has elapsed. Interrupt exception handling
is then executed.
When the priority level of an IRQ interrupt is lower than the interrupt mask level set in the status
register (SR) of the CPU, an interrupt request is not accepted preventing software standby mode
from being canceled.
When falling-edge detection is selected for the NMI pin, drive the NMI pin high before making a
transition to software standby mode. When rising-edge detection is selected for the NMI pin, drive
the NMI pin low before making a transition to software standby mode.
Similarly, when falling-edge detection is selected for the IRQ pin, drive the IRQ pin high before
making a transition to software standby mode. When rising-edge detection is selected for the IRQ
pin, drive the IRQ pin low before making a transition to software standby mode.
(2) Canceling with Power-on Reset
Software standby mode is canceled by a power-on reset with the RES pin. Keep the RES pin low
until the clock oscillation settles.
(3) Canceling with Manual Reset
Note that software standby mode cannot be canceled with a manual reset in this LSI.
Rev. 4.00 Jul. 25, 2008 Page 673 of 750
REJ09B0243-0400