Digi NS9750 - Manual (Page 287)

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S y s t e m C o n t r o l M o d u l e
Programmable timers
NS9750 provides 18 programmable timers:
Software watchdog timer
Bus monitor timer
16 general purpose timers
Software watchdog timer
The software watchdog timer, set to specific time intervals, handles gross system
misbehaviors. The watchdog timer can be set to timeout in longer ranges of time
intervals, typically in seconds.
The software watchdog timer can be enabled or disabled, depending on the operating
condition. When enabled, system software must write to the Software Watchdog
Timer register before it expires. When the timer does timeout, the system is
preconfigured to generate an IRQ, an FIQ, or a RESET to restart the entire system.
General purpose timers/counters
Sixteen general purpose timers/counters (GPTCs), which can be concatenated,
provide programmable time intervals to the CPU when used as one or multiple
timers. There is one I/O pin associated with each timer.
When used as a gated timer, the GPTC I/O pin is an input qualifier (high/low
programmable).
When used as a regular timer (enabled by software) the GPTC I/O pin
serves as a terminal count indicator output.
The timers also can be used independently, as up/down counters that monitor the
frequency of certain events (events capturing). In these situations, the GPTC I/O pin
becomes the clock source of the counter. See "GPIO MUX" on page 34 for information
about GPIO pin-to-timer assignments.
Depending on the application, the source clock frequency of the timers/counters can
be selected as the CPU clock, the CPU clock with multiple divisor options, or an
external pulse event. The source frequency is indicated in the timer clock select field