Z8F042AHJ020SC00TR Zilog, Z8F042AHJ020SC00TR Datasheet - Page 102

• Manufacturer Part Number: Z8F042AHJ020SC00TR
• Description: IC ENCORE XP MCU FLASH 4K 28SSOP
• Manufacturer: Zilog
• Series: Encore!® XP®r

Specifications of Z8F042AHJ020SC00TR

• Core Processor: Z8
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: IrDA, UART/USART
• Peripherals: Brown-out Detect/Reset, LED, LVD, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 23
• Program Memory Size: 4KB (4K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: Z8F042AHJ020SC00T

Watchdog Timer
Operation
Table 56. Watchdog Timer Approximate Time-Out Delays
PS022825-0908
WDT Reload Value
(Hex)
000004
FFFFFF
The Watchdog Timer (WDT) protects against corrupt or unreliable software, power faults,
and other system-level problems which may place the Z8 Encore! XP
devices into unsuitable operating states. The features of Watchdog Timer include:
The Watchdog Timer is a one-shot timer that resets or interrupts the Z8 Encore! XP F082A
Series devices when the WDT reaches its terminal count. The Watchdog Timer uses a ded-
icated on-chip RC oscillator as its clock source. The Watchdog Timer operates in only two
modes: ON and OFF. Once enabled, it always counts and must be refreshed to prevent a
time-out. Perform an enable by executing the WDT instruction or by setting the WDT_AO
Flash Option Bit. The WDT_AO bit forces the Watchdog Timer to operate immediately
upon reset, even if a WDT instruction has not been executed.
The Watchdog Timer is a 24-bit reloadable downcounter that uses three 8-bit registers in
the eZ8 CPU register space to set the reload value. The nominal WDT time-out period is
described by the following equation:
where the WDT reload value is the decimal value of the 24-bit value given by
{WDTU[7:0], WDTH[7:0], WDTL[7:0]} and the typical Watchdog Timer RC oscillator
frequency is 10 kHz. The Watchdog Timer cannot be refreshed after it reaches
The WDT Reload Value must not be set to values below
information about approximate time-out delays for the minimum and maximum WDT
reload values.
•
•
•
WDT Time-out Period (ms)
On-chip RC oscillator.
A selectable time-out response: reset or interrupt.
24-bit programmable time-out value.
WDT Reload Value
16,777,215
(Decimal)
4
=
(with 10 kHz typical WDT oscillator frequency)
WDT Reload Value
------------------------------------------
28 minutes
Typical
400 μs
10
Approximate Time-Out Delay
Z8 Encore! XP
000004H
Minimum time-out delay
Maximum time-out delay
Product Specification
.
Table 56
®
Description
F082A Series
®
F082A Series
Watchdog Timer
provides
000002H
.
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