Z8F021ASH020SC datasheet(47/276 Pages) ZILOG

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PS022815-0206

Reset, STOP Mode Recovery and Low Voltage Detection

Z8 Encore! XP® 4K Series

Product Specification

POR—Power-On Reset Indicator

If this bit is set to 1, a Power-On Reset event occurred. This bit is reset to 0 if a WDT time-

out or STOP Mode Recovery occurs. This bit is also reset to 0 when the register is read.

STOP—STOP Mode Recovery Indicator

If this bit is set to 1, a STOP Mode Recovery occurred. If the STOP and WDT bits are both

set to 1, the STOP Mode Recovery occurred because of a WDT time-out. If the STOP bit

is 1 and the WDT bit is 0, the STOP Mode Recovery was not caused by a WDT time-out.

This bit is reset by a Power-On Reset or a WDT time-out that occurred while not in STOP

mode. Reading this register also resets this bit.

WDT—Watch-Dog Timer Time-Out Indicator

If this bit is set to 1, a WDT time-out occurred. A Power-On Reset resets this pin. A STOP

Mode Recovery from a change in an input pin also resets this bit. Reading this register

resets this bit. This read must occur before clearing the WDT interrupt.

EXT—External Reset Indicator

If this bit is set to 1, a Reset initiated by the external RESET pin occurred. A Power-On

Reset or a STOP Mode Recovery from a change in an input pin resets this bit. Reading this

Reserved—Must be 0.

LVD—Low Voltage Detection Indicator

If this bit is set to 1 the current state of the supply voltage is below the low voltage detec-

tion threshold. This value is not latched but is a real-time indicator of the supply voltage

level.

Table 12. Reset Status Register (RSTSTAT)

BITS

FIELD

POR

STOP

WDT

EXT

Reserved

LVD

RESET

See descriptions below

R/W

RRR

ADDR

FF0H

Reset or STOP Mode Recovery Event

POR

STOP

WDT

EXT

Power-On Reset

1000

Reset using RESET pin assertion

0001

Reset using Watch-Dog Timer time-out

0010

Reset using the On-Chip Debugger (OCTCTL[1] set to 1)

1000

Reset from STOP Mode using DBG Pin driven Low

1000

STOP Mode Recovery using GPIO pin transition

0100

STOP Mode Recovery using Watch-Dog Timer time-out

0110

Z8F021ASH020SC Datasheet(PDF) 47 Page - Zilog, Inc.

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