HD404449 Datasheet, PDF (37/123 Pages) Hitachi Semiconductor – HD404449 SERIES

Low-power mode
operation cycle
HD404449 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
Note: * For IF and IM operation, refer to figure 15.
Figure 22 MCU Operating Sequence (Low-Power Mode Operation)
Note:
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 is not detected. Also, if the low level period after
the falling edge of INT₀ is shorter than the interrupt frame, INT₀ is not 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 to low from high, a falling edge is detected.
In figure 24, the level of the INT₀ signal is sampled by an interrupt frame. In (a) the sampled value
is low at point A, and also low at point B. Therefore, a falling edge is not detected. In (b), the
sampled value is high at point A, and also high at point B. A falling edge is not detected in this
case either.
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