HD404358 Datasheet, PDF (27/102 Pages) Renesas Technology Corp – microcomputer has an A/D converter,

Reset by
RESET input or
by watchdog timer
RAME = 0
RAME = 1
RESET 1 RESET 2
HD404358 Series
Standby mode
f_OSC: Oscillate
ø_CPU: Stop
ø_PER: f_cyc
Active
mode
SBY
instruction
Interrupt
f_OSC: Oscillate
ø_CPU: f_cyc
ø_PER: f_cyc
STOPC
Stop mode
STOP
instruction
f_OSC: Stop
ø_CPU: Stop
ø_PER: Stop
f_OSC: Main oscillation frequency
f_cyc: f_OSC/4
ø_CPU: System clock
ø_PER: Clock for other peripheral
functions
Figure 11 MCU Status Transitions
Active Mode: All MCU functions operate according to the clock generated by the system oscillator OSC ₁
and OSC₂.
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 12.
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