The Arm Cortex M0+ processor includes an
integrated Sytick Timer. SysTick provides a simple, 24-bit, clear-on-write,
decrementing, wrap-on-zero counter with a flexible control mechanism. The counter can be
used in several different ways, for example:
- A variable rate alarm or signal
timer—the duration is range-dependent on the reference clock used and the
dynamic range of the counter
- A simple counter used to measure
time to completion and time used
- An internal clock-source control
based on missing or meeting durations