SH7604 Datasheet, PDF (63/633 Pages) Hitachi Semiconductor – Hardware Manual

To return from standby mode, use a reset or an external NMI interrupt. For resets, the CPU returns
to the ordinary program execution state through the exception handling state when placed in a
reset state after the oscillator stabilization time has elapsed. For NMI interrupts, the CPU returns
to the ordinary program execution state through the exception handling state after the oscillator
stabilization time has elapsed. Turn the cache off before entering standby mode. In this mode,
power consumption drops substantially because the oscillator stops.
Module Standby Function: The module standby function is available for the multiplier (MULT),
divider (DIVU), 16-bit free-running timer (FRT), serial communication interface (SCI), and DMA
controller (DMAC) on-chip peripheral modules.
The supply of the clock to these on-chip peripheral modules can be halted by setting the
corresponding bits 4–0 (MSTP4–MSTP0) in the standby control register (SBYCR). By using this
function, the power consumption can be reduced.
The external pins of the on-chip peripheral modules in module standby mode are reset and all
registers except DMAC, MULT, and DIVU are initialized. The module standby function is cleared
by clearing the MSTP4–MSTP0 bits to 0.
When MULT has entered the software standby mode, do not execute the DMULS.L, DMULU.L,
MAC.L, MAC.W, MUL.L, MULS, and MULU instructions (all of which are multiply
instructions) or any instructions that access the MACH and MACL registers (CLRMAC, LDS
MACH/MACL, STS MACH/MACL).
When the DMAC module standby function is used, set the DMAC’s DMA master enable bit to 0.
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