Z8F160x Zilog, Z8F160x Datasheet - Page 91

• Manufacturer Part Number: Z8F160x
• Description: Z8 Encore / Microcontrollers with Flash Memory and 10 Bit A/D Converter
• Manufacturer: Zilog

Table 45. Watch-Dog Timer Approximate Time-Out Delays
PS017610-0404
WDT Reload Value
FFFFFF
000004
Watch-Dog Timer Refresh
Watch-Dog Timer Time-Out Response
(Hex)
information on approximate time-out delays for the minimum and maximum WDT reload
values.
When first enabled, the Watch-Dog Timer is loaded with the value in the Watch-Dog
Timer Reload registers. The Watch-Dog Timer then counts down to
WDT instruction is executed by the eZ8 CPU. Execution of the WDT instruction causes
the downcounter to be reloaded with the WDT Reload value stored in the Watch-Dog
Timer Reload registers. Counting resumes following the reload operation.\
When the Z8F640x family device is operating in Debug Mode (via the On-Chip Debug-
ger), the Watch-Dog Timer is continuously refreshed to prevent spurious Watch-Dog
Timer time-outs.
The Watch-Dog Timer times out when the counter reaches
Watch-Dog Timer generates either an interrupt or a Short Reset. The WDT_RES Option Bit
determines the time-out response of the Watch-Dog Timer. Refer to the Option Bits chap-
ter for information regarding programming of the WDT_RES Option Bit.
WDT Interrupt in Normal Operation
If configured to generate an interrupt when a time-out occurs, the Watch-Dog Timer issues
an interrupt request to the interrupt controller and sets the WDT status bit in the Watch-Dog
Timer Control register. If interrupts are enabled, the eZ8 CPU responds to the interrupt
request by fetching the Watch-Dog Timer interrupt vector and executing code from the
vector address. After time-out and interrupt generation, the Watch-Dog Timer counter
rolls over to its maximum value of FFFFFH and continues counting. The Watch-Dog
Timer counter is not automatically returned to its Reload Value.
WDT Interrupt in Stop Mode
If configured to generate an interrupt when a time-out occurs and the Z8F640x family
device is in STOP mode, the Watch-Dog Timer automatically initiates a STOP Mode
Recovery and generates an interrupt request. Both the WDT status bit and the STOP bit in
the Watch-Dog Timer Control register are set to 1 following WDT time-out in STOP
WDT Reload Value
16,777,215
(Decimal)
4
Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
(with 50kHz typical WDT oscillator frequency)
Typical
335.5s
80µs
Approximate Time-Out Delay
000000H
Description
Minimum time-out delay
Maximum time-out delay
000000H
. A time-out of the
Watch-Dog Timer
Z8 Encore!
unless a
®
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