saf-xc866-4rri3v Infineon Technologies Corporation, saf-xc866-4rri3v Datasheet - Page 68

• Manufacturer Part Number: saf-xc866-4rri3v
• 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 XC866 system reset. Hence, routine service of the WDT confirms
that the system is functioning properly. This ensures that an accidental malfunction of
the XC866 will be aborted in a user-specified time period. In debug mode, the WDT is
suspended and stops counting. Therefore, there is no need to refresh the WDT during
debugging.
Features:
• 16-bit Watchdog Timer
• Programmable reload value for upper 8 bits of timer
• Programmable window boundary
• Selectable input frequency of f
• Time-out detection with NMI generation and reset prewarning activation (after which
The WDT is a 16-bit timer incremented by a count rate of f
16-bit 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 27
Data Sheet
ENWDT
ENWDT_P
a system reset will be performed)
Figure 27
f
PCLK
Watchdog Timer
Logic
WDT Block Diagram
shows the block diagram of the WDT unit.
1:128
1:2
PCLK
/2 or f
WDTIN
MUX
64
PCLK
/128
WDT Low Byte
Control
WDT
Overflow/Time-out Control &
Window-boundary control
Clear
PCLK
Functional Description
WDT High Byte
WDTWINB
/2 or f
WDTREL
PCLK
V1.2, 2007-10
/128. This
XC866
WDTTO
WDTRST