HD404618 Datasheet, PDF (30/91 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404618 Series
Standby
Oscillator: Active
Peripheral clocks:
Active
All other clocks:
Stopped
Watch
Oscillator: Stopped
Sub-oscillator: Active
Peripheral clocks: Stopped
All other clocks: Stopped
RESET ^No
=1?
Yes
IF0 = ^No
1?
Yes
IM0 =
0 ? No
Yes
IF1 = ^No
1?
Yes
IM1 =
0 ? No
Yes
(SBY only)
IFTA = ^No
1?
Yes
IMTA =
0 ? No
Yes
IFTB = ^No
1?
Yes
IMTB =
0 ? No
Yes
IFTC = ^No
1?
Yes
IMTC =
0 ? No
IFS = ^No
1?
Yes
Yes
IMS =
0 ? No
(SBY only)
(SBY only)
(SBY only) Yes
Restart
processor clocks
Restart
processor clocks
Execute
next instruction
(active mode)
Reset MCU
No
Execute
next instruction
IF = 1,
IM = 0, and
IE = 1 ?
Yes
Accept
interrupt
Figure 11 MCU Operation Flowchart in Watch and Standby Modes
Stop Mode: The MCU enters stop mode if the STOP instruction is executed in active mode when TMA3 =
0. In this mode, the system oscillator stops, which stops all MCU functions as well.
Stop mode is terminated by a RESET input as shown in figure 12. RESET must be high for at least one t_RC
to stabilize oscillation (refer to the AC Characteristics section). When the MCU restarts after stop mode is
cancelled, all RAM contents are retained, but the accuracy of the contents of the accumulator, B register, W
register, X/SPX register, Y/SPY register, carry flag, and serial data register cannot be guaranteed.
28