The existing clock synchronization code has two flaws: intermittent
transmission latency during get_status requests can cause the
estimated clock to be too low, and the estimated clock calculation did
not take into account possible clock drift between samples. The
former could potentially lead to "Timer too close" errors and the
latter could potentially lead to "Move queue empty" errors.
Rework the code to avoid the above problems. It's not necessary to
estimate the micro-controller clock as an excellent estimate is
reported by the micro-controller (via the CLOCK_FREQ constant).
Account for a small drift from the reported value, and check on each
sample if the drift exceeds the expected limits. With a good starting
estimated clock, only the offset needs to be calculated. Use previous
offsets (and the estimated clock) in calculation of new offsets to
avoid intermittent latency from badly skewing the results. Finally,
add an additional time offset of one millisecond to account for any
minor inaccuracies.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
c7d0358c41