z8f083a ZiLOG Semiconductor, z8f083a Datasheet - Page 100

• Manufacturer Part Number: z8f083a
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

Table 55. Watchdog Timer Approximate Time-Out Delays
PS026308-1207
WDT Reload Value
FFFFFF
000004
000400
Watchdog Timer Refresh
Watchdog Timer Time-Out Response
(Hex)
On first enable, the Watchdog Timer is loaded with the value in the WDT reload registers.
The Watchdog Timer counts down to
the eZ8 CPU. Execution of the WDT instruction causes the downcounter to be reloaded
with the WDT reload value stored in the WDT reload registers. Counting resumes
following the Reload operation.
When the Z8 Encore! F083A Series devices are operating in DEBUG mode (using the On-
Chip Debugger), the WDT needs to be continuously refreshed to prevent any WDT Timer
time-outs.
The WDT times out when the counter reaches
generates either an interrupt or a system reset. The WDT_RES Flash option bit determines
the time-out response of the WDT. For more details on programming of WDT_RES Flash
option bit, see
WDT Interrupt in Normal Operation
If configured to generate an interrupt when a time-out occurs, the Watchdog Timer issues
an interrupt request to the interrupt controller and sets the WDT status bit in the reset status
register. If interrupts are enabled, the eZ8 CPU responds to the interrupt request by
fetching the Watchdog Timer interrupt vector and executing code from the vector address.
After time-out and interrupt generation, the Watchdog Timer counter resets to its
maximum value of
automatically return to its reload value.
The reset status register
interrupt. This read clears the WDT time-out flag and prevents further WDT interrupts
occurring immediately.
WDT Reload Value
16,777,215
(Decimal)
Flash Option Bits
1024
FFFFFH
4
(Table 11
and continues counting. The Watchdog Timer counter will not
on page 119.
on page 30) must be read before clearing the WDT
(with 10 kHz typical WDT oscillator frequency)
000000H
28 minutes
Typical
102 ms
400 μs
Approximate Time-Out Delay
000000H
unless a WDT instruction is executed by
. A time-out of the WDT
Z8 Encore!
Minimum time-out delay
Default time-out delay
Maximum time-out delay
Product Specification
Description
®
F083A Series
Watchdog Timer
88