RTEMS C User's Guide
RTEMS provides the rtems_clock_tick directive which is
called from the user's real-time clock ISR to inform RTEMS that
a tick has elapsed. The tick frequency value, defined in
microseconds, is a configuration parameter found in the
Configuration Table. RTEMS divides one million microseconds
(one second) by the number of microseconds per tick to determine
the number of calls to the
rtems_clock_tick directive per second. The
frequency of rtems_clock_tick
calls determines the resolution
(granularity) for all time dependent RTEMS actions. For
example, calling rtems_clock_tick
ten times per second yields a higher
resolution than calling rtems_clock_tick
two times per second. The rtems_clock_tick
directive is responsible for maintaining both
calendar time and the dynamic set of timers.
RTEMS C User's Guide
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