C167CS datasheet(306/517 Pages) INFINEON

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C167CS

Derivatives

The Watchdog Timer (WDT)

User’s Manual

13-6

V2.0, 2000-07

13.2

Reset Source Indication

The reset indication flags in register WDTCON provide information on the source for the

last reset. As the C167CS starts executing from location 00’0000H after any possible

reset event the initialization software may check these flags in order to determine if the

recent reset event was triggered by an external hardware signal (via RSTIN), by

software itself or by an overflow of the watchdog timer. The initialization (and also the

further operation) of the microcontroller system can thus be adapted to the respective

circumstances, e.g. a special routine may verify the software integrity after a watchdog

timer reset.

The reset indication flags are not mutually exclusive, i.e. more than one flag may be set

after reset depending on its source. Table 13-2 summarizes the possible combinations:

Long Hardware Reset is indicated when the RSTIN input is still sampled low (active) at

the end of a hardware triggered internal reset sequence.

Short Hardware Reset is indicated when the RSTIN input is sampled high (inactive) at

the end of a hardware triggered internal reset sequence.

Software Reset is indicated after a reset triggered by the excution of instruction SRST.

Watchdog Timer Reset is indicated after a reset triggered by an overflow of the

watchdog timer.

Note: When bidirectional reset is enabled the RSTIN pin is pulled low for the duration of

the internal reset sequence upon any sort of reset.

Therefore always a long hardware reset (LHWR) will be recognized in any case.

Table 13-2

Reset Indication Flag Combinations

Event

Reset Indication Flags1)

1) Description of table entries:

‘1’ = flag is set, ‘0’ = flag is cleared, ‘–’ = flag is not affected,

‘

∗’ = flag is set in bidirectional reset mode, not affected otherwise.

LHWR

SHWR

SWR

WDTR

Long Hardware Reset

1110

Short Hardware Reset

∗

110

Software Reset

∗∗

–

Watchdog Timer Reset

∗∗

EINIT instruction

000–

SRVWDT instruction

–––0

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