HD6433636SW datasheet(108/418 Pages) RENESAS

108 / 418 page

5.3

Standby Mode

5.3.1

Transition to Standby Mode

The system goes from active mode to standby mode when a SLEEP instruction is executed while

the SSBY bit in SYSCR1 is set to 1, the LSON bit is cleared to 0, and bit TMA3 in timer mode

on-chip peripheral modules stop functioning. As long as a minimum required voltage is applied,

the contents of the CPU registers and some on-chip peripheral function internal registers, and data

in the on-chip RAM, will be retained. The I/O ports go to the high-impedance state.

5.3.2

Clearing Standby Mode

Standby mode is cleared by an interrupt (IRQ

0, IRQ1, WKP0 to WKP7) or by input at the RES pin.

Clearing by Interrupt: When an interrupt is requested, the system clock pulse generator starts.

After the time set in bits STS2 to STS0 in SYSCR1 has elapsed, a stable system clock signal is

supplied to the entire chip, standby mode is cleared, and interrupt exception handling starts.

Operation resumes in active (high-speed) mode if MSON = 0 in SYSCR2, or active (medium-

speed) mode if MSON = 1. Standby mode is not cleared if the I bit of CCR is set to 1 or the

particular interrupt is disabled in the interrupt enable register.

Clearing by

RES Input: When the RES pin goes low, the system clock pulse generator starts.

After the pulse generator output has stabilized, if the

RES pin is driven high, the CPU starts reset

exception handling.

Since system clock signals are supplied to the entire chip as soon as the system clock pulse

generator starts functioning, the

RES pin should be kept at the low level until the pulse generator

output stabilizes.

HD6433636SW Scheda tecnica(PDF) 108 Page - Renesas Technology Corp