7480 datasheet(184/337 Pages) RENESAS

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7480 Group and 7481 Group User's Manual

1-167

1.19 Power Saving Function

HARDWARE

Recovery from Stop Mode by Interrupt

The stop mode is terminated and the XIN oscillation is resumed when an interrupt request is

generated and its interrupt is acceptable in the stop mode.

Next, the oscillator start-up stabilization time is generated by timer 1. After the oscillator start-up

stabilization time elapses, internal clock

φ is resumed and supplied to the CPU.

The interrupt request used to terminate the stop mode is accepted and the interrupt service routine

is executed.

After the interrupt service routine is completed, the program is executed at the instruction following

the STP instruction.

Note: The state of timer 1 is affected by recovering from the stop mode.

The interrupt sources used for recovery from the stop mode are as follows:

• INT0, INT1

• CNTR0, CNTR1

• Serial I/O (only when external clock (or its 1/16) is selected as the synchronous clock)

• Timer X and timer Y (only in event count mode)

• Key inputs (in key-on wakeup)

Figure 1.19.6 shows an operation example at recovery from the stop mode by the INT0 interrupt.

Figure 1.19.6 Operation Example at Recovery from Stop Mode by INT0 Interrupt

XIN

FF16

0016

Operating

Stop

Operating

CPU

Peripheral device

Stop (Note 2)

Counting down

Contents of timer 1

INT0 pin input

INT0 interrupt

request bit

INT0 interrupt

request accepted

Undefined

: Reload

: Underflow

• INT0 interrupt is used for recovery from stop mode (rising edge detected)

Stop mode

STP

executed

Stop mode is terminated

by INT0 interupt

Oscillation start-up stabilization time

2048 cycles of XIN pin input signal

XIN pin : High-impedance state

STP instruction execution

cycle (Note 1)

Notes 1: 2 cycles of internal clock

2: Timer operates in event count mode.

Serial I/O operates when the external clock input (or its 1/16) is

used as the synchronous clock.

instruction

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