HD404328UH View Datasheet(PDF) - Renesas Electronics

Part Name

Description

Manufacturer

HD404328UH

4-bit HMCS400-series microcomputer

Renesas Electronics 

HD404328 Series

Operation during mode transition is the same as that at standby mode cancellation (figure 11).

Subactive Mode: The CPU operates with a clock generated by the X1 and X2 oscillation circuits.

Functions that can operate in subactive mode are listed in table 20. When the STOP or SBY instruction is

executed in subactive mode, the MCU enters either watch or active mode, depending on the statuses of

LSON and DTON. The DTON flag can only be set in subactive mode; it is automatically reset after a

transition to active mode.

The subactive mode is an optional function that the user must specify on the function option list.

Interrupt Frame: In watch and subactive modes, timer A and INT0 interrupts are generated in

synchronism with the interrupt frame. Three interrupt frame lengths (T) can be selected by the settings of

the miscellaneous register, as shown in figure 14.

The time from an interrupt strobe to interrupt request generation is the oscillation stabilization period (tRC),

as shown in figure 13.

The interrupt request is generated synchronously with the interrupt strobe timing except during transition to

active mode. The falling edge of the INT0 signal is input asynchronously with the interrupt frame timing,

but it is regarded as input synchronously with the second interrupt strobe clock after the falling edge. An

overflow and interrupt request in timer A is generated synchronously with the interrupt strobe timing.

Operation during the transition from watch mode to active mode is the same as that at standby mode

cancellation (figure 11).

Direct Transfer: By controlling the DTON flag, the MCU will be placed directly from subactive to active

mode. The detailed procedure is as follows:

• Set the DTON flag in subactive mode while LSON = 0 and DTON = 1.

• Execute the STOP or SBY instruction.

• After the oscillation stabilization time (a fixed value), the MCU will move automatically from subactive

to active mode (see figure 15).

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 (tD) from subactive to active mode is tRC < tD < T + tRC.

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