HD404019R Datasheet, PDF (38/65 Pages) Renesas Technology Corp – CMOS 4-bit single-chip microcomputers

HD404019R Series
Standby mode may be cancelled by inputting RESET or by asserting an interrupt request. In the former
case the MCU is reset. In the later case, the MCU becomes active and executes the next instruction
following the SBY instruction. If the interrupt enable flag is 1 when an interrupt request is asserted, the
interrupt is executed, while if it is 0, the interrupt request is put on hold and normal instruction execution
continues.
Figure 19 shows the flowchart of the standby mode.
Standby
Oscillator: Active
Peripheral clocks: Active
All other clocks: Stop
RESET ^No
= 1?
Yes
No
IF0 = 1?
Yes
IM0 = 0?
No
Yes
No
IF1 = 1?
Yes
No
IFTA = 1?
IM1 = 0?
No
Yes
Yes
IMTA = 0?
No
Yes
No
IFTB = 1?
Yes
IMTB = 0?
No
Yes
No
IFS = 1?
Yes
No
IMS = 0?
Yes
Restart
processor clocks
Restart
processor clocks
Execute next
instruction
(active mode)
Reset MCU
Execute
instruction
No
IE = 1?
Yes
Accept
interrupt
Figure 19 MCU Operating Flowchart in Standby Mode
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