HD404374FT datasheet(51/161 Pages) RENESAS

51 / 161 page

HD404374/HD404384/HD404389/HD404082/HD404084 Series

Rev.5.00, Sep.11.2003, page 51 of 161

Direct transition from subactive to active mode (Applies to HD404374 Series):

A direct transition can be made from subactive mode to active mode by controlling the direct transfer on

flag (DTON: $020,3) and low speed on flag (LSON: $020,0). The procedure is shown below.

(a) Set LSON = 0 and DTON = 1 in subactive mode.

(b) Execute a STOP or SBY instruction.

automatically switches from subactive mode to active mode (figure 16).

Notes: 1. The DTON flag ($020,3) can be set in only subactive mode. It is always in the reset state in

active mode.

2. The condition for transition time T

D from the subactive mode to active mode is as follows:

RC < TD < T + tRC.

Subactive mode

STOP/SBY

instruction execution

MCU internal

processing time

Oscillation

stabilization time

Active mode

(Set LSON =0, DTON =1)

Interrupt strobe

Direct transition

completion timing

tRC

T: Interrupt frame period

tRC: Oscillation settling time

TD: Direct transition time

Figure 16 Direct Transition Timing

MCU operation sequence:

The MCU operates in accordance with the flowchart shown in figure 17.

RESET input is asynchronous

input, and the MCU immediately enters the reset state upon

RESET input, regardless of its current state.

In the low-power mode operation sequence, if a STOP/SBY instruction is executed while the IE flag is

cleared and the interrupt flag is set, releasing the relevant interrupt mask, the STOP/SBY instruction is

canceled (regarded as NOP) and the next instruction is executed. Therefore, when executing a STOP/SBY

instruction, all interrupt flags must be cleared, or interrupts masked, beforehand.

HD404374FT Datasheet(PDF) 51 Page - Renesas Technology Corp