z16f2811 ZiLOG Semiconductor, z16f2811 Datasheet - Page 249

• Manufacturer Part Number: z16f2811
• Description: High Performance Microcontrollers
• Manufacturer: ZiLOG Semiconductor

Watchdog Timer
Operation
PS022006-0207
WDT Time-out Period (ms)
The Watchdog Timer (WDT) helps protect against corrupt or unreliable software, power
faults, and other system-level problems which places the ZNEO Z16F Series device into
unsuitable operating states.
The WDT includes the following features:
•
•
•
The WDT is a retriggerable one-shot timer that resets or interrupts the ZNEO Z16F Series
device, when the WDT reaches its terminal count. The WDT uses its own dedicated
on-chip RC oscillator as its clock source. The WDT has only two modes of operation—on
and off. Once enabled, it always counts and must be refreshed to prevent a time-out. An
enable is performed by executing the
The
been executed.
To minimize power consumption, the RC oscillator is disabled. The RC oscillator is
disabled by clearing the
is disabled, the WDT will not operate.
The WDT is a 16-bit reloadable downcounter that uses two 8-bit registers in the ZNEO
CPU register space to set the reload value. The nominal WDT time-out period is given by
the following equation:
where, WDT reload value is the decimal value of the 16-bit value given by {WDTH[7:0],
WDTL[7:0]} and the typical Watchdog Timer RC oscillator frequency is 10 kHz.
Table 119
minimum, default, and maximum WDT reload values.
On-chip RC oscillator.
A selectable time-out response: short reset or system exception.
16-bit programmable time-out value.
WDT_AO
on page 236 provides information on approximate time-out delays for the
bit enables the WDT to operate all the time, even if a
WDTEN
P R E L I M I N A R Y
bit in the
=
WDT Reload Value
------------------------------------------------- -
WDT
Oscillator Control
instruction or by setting the
10
Register. If the RC oscillator
Product Specification
ZNEO
WDT
WDT_AO
instruction has not
™
Watchdog Timer
Z16F Series
option bit.
235