SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 249

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

13
To allow recovery from software or hardware failure, the C164CM provides a Watchdog
Timer. If the software fails to service this timer before an overflow occurs, an internal
reset sequence will be initiated. This internal reset will also pull the RSTOUT pin low,
which in turn resets the peripheral hardware which might have caused the malfunction.
If the watchdog timer is enabled and the software has been designed to service it
regularly before it overflows, the watchdog timer will supervise the program execution so
it will overflow only if the program does not progress properly. The watchdog timer will
also time out if a software error was caused by hardware related failures. This prevents
the controller from malfunctioning for a time longer than specified by the user.
Note: When the bidirectional reset is enabled, pin RSTIN will be pulled low for the
The watchdog timer provides two registers:
• a read-only timer register containing the current count, and
• a control register for initialization and reset source detection.
Figure 13-1 SFRs and Port Pins Associated with the Watchdog Timer
The watchdog timer is a 16-bit up counter which is clocked with the prescaled CPU clock
(
• by 2 (WDTIN = ‘0’, WDTPRE = ‘0’), or
• by 4 (WDTIN = ‘0’, WDTPRE = ‘1’), or
• by 128 (WDTIN = ‘1’, WDTPRE = ‘0’), or
• by 256 (WDTIN = ‘1’, WDTPRE = ‘1’).
User’s Manual
f
CPU
). The prescaler divides the CPU clock:
duration of the internal reset sequence upon a software reset or a watchdog timer
reset.
Reset Indication Pins
Watchdog Timer (WDT)
RSTOUT
(deactivated by EINIT)
RSTIN
(bidirectional reset only)
WDT
Data Registers
13-1
Watchdog Timer (WDT)
Control Registers
WDTCON
C164CM/C164SM
Derivatives
MCA04381
V1.0, 2002-02