HD404669 Datasheet, PDF (38/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
Direct Transition from Subactive Mode to Active Mode: Available by controlling the direct transfer on
flag (DTON: $020, bit 3) and the low speed on flag (LSON: $020, bit 0). The procedures are described
below:
• Set LSON to 0 and DTON to 1 in subactive mode.
• Execute the STOP or SBY instruction.
• The MCU automatically enters active mode from subactive mode after waiting for the MCU internal
processing time and oscillation stabilization time (figure 19).
Notes: 1. The DTON flag can be set only in subactive mode. It is always reset in active mode.
2. The transition time (T_D) from subactive mode to active mode:
t_RC < T_D < T + t_RC
STOP/SBY instruction execution
Subactive mode
MCU internal
processing time
(Set LSON = 0, DTON = 1)
Oscillation
stabilization
time
Active mode
Interrupt strobe
Direct transfer
completion timing
T
t _RC
T_D
T: Interrupt frame period
t _RC : Oscillation stabilization time
T_D : Direct transition time
Figure 19 Direct Transition Timing
MCU Operation Sequence: The MCU operates in the sequence shown in figure 20. It is reset by an
asynchronous RESET input, regardless of its status.
With the IE flag cleared and an interrupt request flag set together with its interrupt mask cleared, if a
STOP/SBY instruction is executed, the instruction is cancelled (regarded as an NOP) and the following
instruction is executed. Before executing a STOP/SBY instruction, make sure all interrupt request flags are
cleared or all interrupts are masked.
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