HD6417021 Hitachi Semiconductor, HD6417021 Datasheet - Page 448

• Manufacturer Part Number: HD6417021
• Description: SuperH RISC engine
• Manufacturer: Hitachi Semiconductor

18.4.3
In this example, the standby mode is entered on the falling edge of the NMI signal and canceled
on the rising edge of the NMI signal. Figure 18.1 shows the timing.
After an NMI interrupt is accepted (high goes to low) while the NMI edge select bit NMIE in the
interrupt control register ICR is cleared to 0 to select detection of the falling edge, the NMI
exception service routine sets the NMIE to 1 (selecting detection of the rising edge) and sets the
SBY bit to 1. Finally, it executes a SLEEP instruction to enter the standby mode.
The standby mode is canceled on the rising edge of the NMI signal.
Oscillator
SSBY
NMIE
NMI
CK
Standby Mode Application
Figure 18.1 NMI Timing for the Standby Mode (Example)
processing
exception
NMI
instruction
Exception
SBY = 1
service
SLEEP
routine
Standby
mode
Oscillation
Clock setting time
start
time
Time
WDT
set
in
processing
exception
HITACHI 439
NMI