SM8521 Datasheet, PDF (27/56 Pages) Sharp Electrionic Components – 8-Bit Single-Chip Microcomputer

SM8521
Standby Function
The standby function is a function which
temporarily stops program execution so as to
conserve power. The standby mode is when the
chip enters temporary stop state from the operating
state, executing program. It contains both STOP
and HALT modes, either of which can be selected
according to your desires.
If the CPU executes the STOP mode or HALT
mode, the chip will switch to standby mode from an
operating mode. If the wake up source of the
standby mode encounters an interrupt the chip
returns to operating mode from the standby mode.
Fig. 11 shows its state transition diagram.
External reset request
Hardware Reset
Warming up
end
HALT Mode
Internal/external
reset request
HALT instruction
execution
HALT mode
wake up source
STOP mode
wake up source
Normal Operation
STOP instruction
execution
STOP Mode
Operating Mode
Standby Mode
NOTE : When the chip wakes up from STOP mode, it returns to operating mode behind warming up period.
Fig. 11 State Transition Diagram
NOTE :
The STOP instruction is also used for clock change function,
which its operation is different from switching the chip to
STOP mode, take care to use it.
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