HD404829R Datasheet, PDF (35/149 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a LCD controller/Driver Circuit

HD404829R Series
Standby Mode: In standby mode, the oscillators continue to operate, but the clocks related to instruction
execution stop. Therefore, the CPU operation stops, but all RAM and register contents are retained, and the
D or R port status, when set to output, is maintained. Peripheral functions such as interrupts, timers, and
serial interface continue to operate. The power dissipation in this mode is lower than in active mode
because the CPU stops.
The MCU enters standby mode when the SBY instruction is executed in active mode.
Standby mode is terminated by a RESET input or an interrupt request. If it is terminated by RESET input,
the MCU is reset as well. After an interrupt request, the MCU enters active mode and executes the next
instruction after the SBY instruction. If the interrupt enable flag is 1, the interrupt is then processed; if it is
0, the interrupt request is left pending and normal instruction execution continues. A flowchart of
operation in standby mode is shown in figure 15.
Stop mode
Standby mode
Watch mode
No
RESET = 1?
No
RESET = 1?
Yes
No
STOPC = 0?
Yes
RAME = 1
Yes
No
IF0 • IM0 = 1?
RAME = 0
Yes
No
IF1 • IM1 = 1?
Yes ^*1
IFTA • IMTA
No
= 1?
Yes
IFTB •
IMTB + IF2 •
No
IM2 = 1?
Yes^*1 IFTC •
IMTC + IF3 •
No
IM3 = 1?
Yes^*1 IFTD •
IMTD + IF4 •
No
IM4 = 1?
Yes^*1
No
*2
System clock
oscillator started
Yes^*1
System reset
Notes: 1. Only when clearing from standby mode
2. IFAD • IMAD + IFS • IMS = 1
Next instruction
execution
System clock
oscillator started
No
Next instruction
execution
IF = 1,
IM = 0,
IE = 1?
Yes
Interrupts
enabled
Figure 15 MCU Operation Flowchart
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