saf-xc878m-16ffi5v Infineon Technologies Corporation, saf-xc878m-16ffi5v Datasheet - Page 90

• Manufacturer Part Number: saf-xc878m-16ffi5v
• Description: 8-bit Single-chip Microcontroller
• Manufacturer: Infineon Technologies Corporation

3.10
The Watchdog Timer (WDT) provides a highly reliable and secure way to detect and
recover from software or hardware failures. The WDT is reset at a regular interval that is
predefined by the user. The CPU must service the WDT within this interval to prevent the
WDT from causing an XC87x system reset. Hence, routine service of the WDT confirms
that the system is functioning properly. This ensures that an accidental malfunction of
the XC87x will be aborted in a user-specified time period.
In debug mode, the WDT is default suspended and stops counting. Therefore, there is
no need to refresh the WDT during debugging.
Features
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The WDT is a 16-bit timer incremented by a count rate of
timer is realized as two concatenated 8-bit timers. The upper 8 bits of the WDT can be
preset to a user-programmable value via a watchdog service access in order to modify
the watchdog expire time period. The lower 8 bits are reset on each service access.
Figure 24
Figure 24
Data Sheet
ENWDT
ENWDT_P
16-bit Watchdog Timer
Programmable reload value for upper 8 bits of timer
Programmable window boundary
Selectable input frequency of
Time-out detection with NMI generation and reset prewarning activation (after which
a system reset will be performed)
f
PCLK
shows the block diagram of the WDT unit.
Watchdog Timer
Logic
WDT Block Diagram
1:128
1:2
f
PCLK
WDTIN
/2 or
MUX
83
f
PCLK
/128
WDT Low Byte
Control
WDT
Overflow/Time-out Control &
Window-boundary control
Clear
f
PCLK
/2 or
Functional Description
WDT High Byte
WDTWINB
WDTREL
f
PCLK
/128. This 16-bit
XC87xCLM
V1.5, 2011-03
FNMIWDT
WDTRST
.