M38043FDHKP datasheet(278/387 Pages) RENESAS

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2-154

APPLICATION

2.12 Standby function

Rev.1.00 Jan 14, 2005

REJ09B0212-0100Z

3804 Group (Spec.H)

(2)

Release of wait mode

The wait mode is released by reset input or by the occurrence of an interrupt request. Note the

differences in the restoration process according to reset input or interrupt request, as described

below.

In the wait mode, oscillation is continued, so an instruction can be executed immediately after the

wait mode is released.

sRestoration by reset input

The wait mode is released by holding the input level of the RESET pin at “L” in the wait mode.

Upon release of the wait mode, all ports are in the input state, and supply of the internal clock

φ to the CPU is started. To reset the microcomputer, the RESET pin should be held at an “L” level

for 16 cycles or more of XIN. The reset state is released in approximately 10.5 cycles to 18.5 cycles

of the XIN input after the input of the RESET pin is returned to the “H” level.

At release of wait mode, the internal RAM retains its contents previous to the reset. However, the

previous contents of the CPU register and SFR are not retained.

Figure 2.12.3 shows the reset input time.

For more details concerning reset, refer to “2.10 Reset”.

Fig. 2.12.3 Reset input time

Vcc

RESET

XIN

Wait mode

16 cycles of XIN

Operating mode

Time to hold internal reset state =

approximately 10.5 to 18.5 cycles of XIN input

Note: Some cases may occur in which no waveform is input to XIN (in low-speed mode).

(Note)

Execute WIT instruction

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