ST10R272L - ARCHITECTURAL OVERVIEW
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2.4.7
General purpose timer (GPT)
The GPT unit is a flexible multifunctional timer/counter structure used for many different
time-related tasks such as event timing and counting, pulse width and duty-cycle
measurements, pulse generation or pulse multiplication.
The GPT unit incorporates five 16-bit timers, organized in two separate modules, GPT1 and
GPT2. Each timer in each module may operate independently in a number of different
modes, or may be concatenated with another timer of the same module.
2.4.8 Watchdog
timer
The Watchdog Timer is a fail-safe mechanism which limits the maximum malfunction time of
the controller. The Watchdog Timer is always enabled after device reset, and can only be
disabled in the time interval until the EINIT (end of initialization) instruction has been
executed. In this way, the chip’s start-up procedure is always monitored. The software must
be designed to service the Watchdog Timer before it overflows. If, due to hardware or
software related failures, the software fails to maintain the watchdog timer, it will overflow
generating an internal hardware reset and pulling the RSTOUT pin low to reset external
hardware components.
The Watchdog Timer is a 16-bit timer, clocked with the system clock divided either by 2 or
128. The high byte of the Watchdog Timer register can be set to a pre-specified reload value
to allow further variation of the monitored time interval. Each time it is serviced by the
application software, the high byte of the Watchdog Timer is reloaded.
2.5
Protected bits
The ST10R272L provides a special bit protection mechanism. Bits which can be modified by
the on-chip hardware, cannot be unintentionally changed by software accesses to related
bits (“Bit-handling and bit-protection” on page 45).
The following bits are protected:
Register
Bit Name
Notes
T2IC, T3IC, T4IC
T2IR, T3IR, T4IR
GPT1 timer interrupt request flags
T5IC, T6IC
T5IR, T6IR
GPT2 timer interrupt request flags
CRIC
CRIR
GPT2 CAPREL interrupt request flag
T3CON, T6CON
T3OTL, T6OTL
GPTx timer output toggle latches
S0TIC, S0TBIC
S0TIR, S0TBIR
ASC0 transmit(buffer) interrupt request flags
Table 2 Protected bits