HD404618 Datasheet, PDF (32/91 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404618 Series
LSON and DTON. The DTON flag can only be set in subactive mode; it is automatically reset after a
transition to active mode.
Subactive mode is an optional function that the user must specify on the function option list.
Interrupt Frame: In watch and subactive modes, Ø_CLK is supplied for timer A and the INT₀ circuit.
Prescaler W and timer A operate as time bases to generate interrupt frame timing. Three interrupt frame
cycles (T) can be selected by the settings of the miscellaneous register, as shown in figure 14.
In watch and subactive modes, timer A and INT₀ interrupts are generated in synchronism with the interrupt
frame. An interrupt request is generated at the interrupt strobe timing, except when the MCU enters active
mode from watch mode. The INT₀ falling edge is acknowledged regardless of the interrupt frame, but the
interrupt is executed simultaneously with the next interrupt strobe. Timer A generates an overflow and
interrupt request at the timing of an interrupt strobe.
MIS: $00C
MIS2 MIS1 MIS0
t _RC selection
Refer to
table 20
MIS
Bit 1 Bit 0
0
0
0
1
1
0
1
1
T ^*1
t
*1
RC
0.12207 ms
0.24414 ms
0.24414 ms ^*2
15.625 ms
7.8125 ms
62.5 ms
31.25 ms
Not used
Oscillation circuit
condition
External clock input
400/800-kHz
ceramic oscillator
—
Notes: 1. The value of t _RC applies only when using a 32.768-kHz oscillator.
2. Only direct transfer.
Figure 14 Miscellaneous Register
Direct Transfer: By controlling the DTON, the MCU would be placed directly from subactive to active
mode. The detailed procedure is as follows:
• Set the DTON flag in subactive mode while LSON = 0.
• Execute the STOP or SBY instruction.
• After the oscillation stabilization time (a fixed value), the MCU will move automatically from subactive
to active mode.
Note that DTON ($020, bit 3) is valid only in subactive mode. When the MCU is in active mode, this flag
is always at reset.
The transition time (t_D) from subactive to active mode is t_RC < t_D < T + t_RC.
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