HD404849 Datasheet, PDF (38/125 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

Low-power mode
operation cycle
HD404849 Series
IF = 1 and
No
IM = 0?
Yes
Standby/watch
mode
Stop mode
Hardware NOP
execution
No
IF = 1 and
IM = 0?
Yes
Hardware NOP
execution
No
STOPC = 0?
Yes
RAME = 1
PC ← Next
Iocation
PC ← Next
Iocation
Instruction
execution
Reset MCU
MCU operation
cycle
For IF and IM operation, refer to figure 15.
Figure 22 MCU Operating Sequence (Low-Power Mode Operation)
Notes on Use:
• When the MCU is in watch mode or subactive mode, if the high level period before the falling edge of
INT₀ is shorter than the interrupt frame, INT₀ will not be detected. Also, if the low level period after the
falling edge of INT₀ is shorter than the interrupt frame, INT₀ will not be detected.
Edge detection is shown in figure 23. The level of the INT₀ signal is sampled by a sampling clock.
When this sampled value changes from high to low, a falling edge is detected.
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