ZUSBOPTSC01ZACG datasheet(113/282 Pages) ZILOG

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PS022827-1212

P R E L I M I N A R Y

Watchdog Timer Control Register

Z8 Encore! XP® F082A Series

Product Specification

into the Watchdog Timer Reload registers results in a one-second time-out at room tem-

perature and 3.3V supply voltage. Time-outs other than one second may be obtained by

scaling the calibration values up or down as required.

The Watchdog Timer accuracy still degrades as temperature and supply voltage vary. See

Table 137 on page 235 for details.

Watchdog Timer Control Register Definitions

This section defines the features of the following Watchdog Timer Control registers.

Watchdog Timer Control Register (WDTCTL): see page 96

Watchdog Timer Reload Upper Byte Register (WDTU): see page 97

Watchdog Timer Reload High Byte Register (WDTH): see page 97

Watchdog Timer Reload Low Byte Register (WDTL): see page 98

Watchdog Timer Control Register

The Watchdog Timer Control (WDTCTL) Register is a write-only control register. Writ-

ing the 55H, AAH unlock sequence to the WDTCTL Register address unlocks the three

Watchdog Timer Reload Byte registers (WDTU, WDTH and WDTL) to allow changes to

the time-out period. These write operations to the WDTCTL Register address produce no

effect on the bits in the WDTCTL Register. The locking mechanism prevents spurious

writes to the reload registers. This register address is shared with the read-only Reset Sta-

tus Register.

Table 59. Watchdog Timer Control Register (WDTCTL)

Bit

Field

WDTUNLK

RESET

XXXXXXXX

R/W

WWWWWWWW

Address

FF0H

Note: X = Undefined.

Bit

Description

[7:0]



WDTUNLK

Watchdog Timer Unlock

The software must write the correct unlocking sequence to this register before it is allowed

to modify the contents of the Watchdog Timer reload registers.

Note:

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