HD404849 Datasheet, PDF (34/125 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

Active mode
Watch mode
HD404849 Series
Oscillation
stabilization period
Active mode
Interrupt strobe
INT₀
Interrupt request
generation
(During the transition
from watch mode to
active mode only)
T
T
t _RC
Tx
T: Interrupt frame length
t_RC : Oscillation stabilization period
Figure 17 Interrupt Frame
Miscellaneous register (MIS: $00C)
Bit
Initial value
Read/Write
Bit name
3
0
W
MIS3
2
0
W
MIS2
1
0
W
MIS1
0
0
W
MIS0
MIS3 MIS2
Buffer control.
Refer to figure 38.
MIS1
0
0
1
1
MIS0
0
1
0
1
T^*1
t_RC^{* 1}
Oscillation circuit conditions
0.24414 ms 0.12207 ms External clock input
0.24414 ms^{* 2}
15.625 ms 7.8125 ms Ceramic oscillator
62.5 ms 31.25 ms
Crystal oscillator
Not used
—
Notes: 1. The values of T and t_RC are applied when a 32.768-kHz crystal oscillator is used.
2. The value is applied only when direct transfer operation is used.
Figure 18 Miscellaneous Register (MIS)
Subactive Mode: The OSC₁ and OSC₂ oscillator stops and the MCU operates with a clock generated by
the X1 and X2 oscillator. In this mode, functions except the A/D conversion operate. However, because
the operating clock slows down, power dissipation is reduced, next least to watch mode.
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