Usage Notes - Renesas H8S Series Hardware Manual

Oscillator
ø
NMI
NMIEG
SSBY
21.6.5

Usage Notes

I/O Port Status: In software standby mode, I/O port states are retained. If the OPE bit is set to 1, the address bus and bus
control signal output is also retained. Therefore, there is no reduction in current dissipation for the output current when a
high-level signal is output.
Current Dissipation during Oscillation Stabilization Wait Period: Current dissipation increases during the oscillation
stabilization wait period.
Write Data Buffer Function: The write data buffer function and software standby mode cannot be used at the same time.
When the write data buffer function is used, the WDBE bit in BCRL should be cleared to 0 to cancel the write data buffer
function before entering software standby mode. Also check that external writes have finished, by reading external
addresses, etc., before executing a SLEEP instruction to enter software standby mode. See section 6.9, Write Data Buffer
Function, for details of the write data buffer function.
NMI exception Software standby mode
handling (power-down mode)
NMIEG=1
SSBY=1
SLEEP instruction
Figure 21-2 Software Standby Mode Application Example
NMI exception
Oscillation
handling
stabilization
time t
OSC2
Rev.6.00 Oct.28.2004 page 677 of 1016
REJ09B0138-0600H