Z8F16800144ZCOG Zilog, Z8F16800144ZCOG Datasheet - Page 151

• Manufacturer Part Number: Z8F16800144ZCOG
• Description: KIT DEV FOR Z8F642 MCU 44 PIN
• Manufacturer: Zilog
• Series: Z8 Encore!®r
• Type: MCUr

Specifications of Z8F16800144ZCOG

• Contents: Hardware, Software and Documentation
• For Use With/related Products: Z8F642
• For Use With: 269-4661 - KIT ACC ETHERNET SMART CABLE
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 269-4678

Watchdog Timer
Operation
PS025011-1010
Watchdog Timer (WDT) helps protect against corrupted, or unreliable software and other
system-level problems that may place the Z8 Encore! XP F1680 Series into unsuitable
operating states. The WDT includes the following features:
•
•
•
The WDT is a retriggerable one-shot timer that resets or interrupts the Z8 Encore! XP
F1680 Series 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 timeout. An enable can be performed by executing the WDT instruction or by setting the
WDT_AO
WDT instruction has not been executed.
To minimize power consumption, the RC oscillator can be disabled. The RC oscillator is
disabled by clearing the
disabled, the WDT will not operate.
The WDT is a 16-bit reloadable downcounter that uses two 8-bit registers in the eZ8 CPU
register space to set the reload value. The nominal WDT timeout period is calculated by
the following equation:
where the WDT reload value is given by {
Watchdog Timer RC oscillator frequency is 10 kHz. You must consider system 
requirements when selecting the timeout delay.
approximate timeout delays for the default and maximum WDT reload values.
Table 80. Watchdog Timer Approximate Timeout Delays
WDT Reload
Value (Hex)
On-chip RC oscillator
A selectable timeout response: Reset or System Exception
16-bit programmable timeout value
FFFF
0400
WDT Time Out Period ms
Option Bit. The
WDT Reload
Value
(Decimal)
–
65,536
1024
WDTEN
WDT_AO
P R E L I M I N A R Y

bit in the
Approximate Timeout Delay
(with 10 kHz typical WDT Oscillator Frequency)
Typical

bit enables the WDT to operate all the time, even if a
=
102 ms
6.55 s
WDT Reload Value
------------------------------------------------------- -
Table 170
WDTH[7:0]
10
Description
Reset default value timeout delay.
Maximum timeout delay.
Table 80
on page 308. If the RC oscillator is
,
Z8 Encore! XP
WDTL[7:0]
provides information on 
Product Specification
} and the typical
®
F1680 Series
Watchdog Timer
137