107
3.13 Low-power Consumption
LDI:8
#01010000b,R1
; SLEP=1
STB
R1,@R0
NOP
;
NOP
;
NOP
;
NOP
;
NOP
;
s Returning from the Sleep Status
Interrupt or hardware standby reset returns the CPU from the sleep status.
r Return by interrupt
If the interrupt enable bit accompanying the peripheral function is valid, a peripheral interrupt
returns the CPU return from the sleep status.
The return procedure from the sleep status to the ordinary operation status is as follows:
Interrupt ==> Restart of internal bus clock supply ==> Restart of internal CPU clock supply
After the restart of clock supplies, the program processing becomes as follows:
If the interrupt level is permitted by the I flag in the ILM register of the CPU
After the register is saved, an interrupt vector is imported and executed by the interrupt
processing routine.
If the interrupt level is prohibited by the I flag in the ILM register of the CPU
After the register is saved, an interrupt vector is imported and executed by the processing
starts from the next instruction after the instruction that set the sleep status.
r Return by reset other than hardware standby reset
The return procedure from the sleep status to the ordinary operation status is as follows:
Internal reset ==> Restart of internal bus clock supply ==> Restart of internal CPU clock supply
==> Import of reset vector ==> Restart of execution from reset entry address
r Return using the HSTX pin
The return procedure from the sleep status to the ordinary operation status is as follows:
Low-level signal application to HSTX pin ==> Transition to hardware standby state ==> High-
level signal application to HSTX pin ==> Internal reset ==> Restart of oscillation circuit ==> Wait
for stabilization ==> Restart of internal peripheral clock supply ==> Restart of internal DMA
clock supply ==> Restart of internal bus clock supply ==> Restart of internal CPU clock supply
==> Import of reset vector ==> Restart of execution from reset entry address
Precautions:
A peripheral interrupt in use for a DMA transfer request cannot return the CPU from the
sleep status.
If there is already a peripheral interrupt, the CPU does not change to the sleep status.
If a DMA request and a sleep request are issued simultaneously, the DMA request has
priority.