[riot-notifications] [RIOT] Kinetis: hwtimer refactor (#3146)
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Tue Jun 2 19:36:37 CEST 2015
This PR reduces the number of lost ticks in the Kinetis hwtimer, see #3139
The number of lost ticks is reduced to 14 in a 900 second test run of tests/vtimer_msg, that corresponds to a timer error of less than 0.5 µs / sec. Lost ticks are not good, but at least at this rate the hwtimer_now clock is actually usable.
Note: these lost ticks that this PR is trying to reduce are purely in software, it does not matter if the RTC crystal is slow/fast or otherwise bad, as both LPTMR and RTT was running off the same crystal source during the test and should therefore count up at the same time.
- Use hwtimer_set for hwtimer_set_absolute()
- Collect hwtimer statistics with #if ENABLE_STATS
- Assembler optimized functions for CNR handling
- Correct another off-by-1, after counter reset in hwtimer_set
- Defer CMR update from hwtimer_unset until ISR fires
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-- Commit Summary --
* kinetis: hwtimer refactor/rewrite
-- File Changes --
M cpu/kinetis_common/hwtimer_arch.c (242)
-- Patch Links --
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