[riot-notifications] [RIOT] Kinetis: hwtimer refactor (#3146)

Joakim Gebart notifications at github.com
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 ┬Ás / 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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